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Design of Microwave Filters(微波滤波器设计)

Design of Microwave Filters Ralph Levy,Life Fellow,IEEE,Richard V.Snyder,Fellow,IEEE,and George Matthaei,Fellow,IEEEInvited PaperAbstract—A survey of the major techniques used in the designof microwave filters is presented in this paper.It is shown thatthe basis for much fundamental microwave filter theory lies in therealm of lumped-element filters,which indeed are actually used di-rectly for many applications at microwave frequencies as high as18GHz.Many types of microwave filters are discussed with theobject of pointing out the most useful references,especially for anewcomer to the field.Index Terms—Bandpass,cavity,ceramic,coaxial,combline,diplexers,evanescent mode,filters,hairpin line,high-pass,hightemperature,interdigital,low-pass,lumped element,microstrip,microwave,multiplexers,parallel coupled line,planar,stripline,superconducting,waveguide.I.R OLE OF L UMPED-E LEMENT F ILTERS IN M ICROW A VEI MPLEMENTATIONS AND D ESIGNS IGNIFICANT developments have taken place since thepublication of the previous survey published in the1984Special Centennial Issue of this T RANSACTIONS[1].Oneimportant aspect of microwave filters,which was not coveredthen,is the lumped-element filter,which was starting to makean impact at about that time,actually beginning in the late1970s.Lumped-element filters are now used at microwavefrequencies up to about18GHz,and form a large percentage ofmicrowave filters produced by the industry.The unloadedtwo papers that appeared in Microwave Journal in the 1980s [3],[4].Several of the design principles are briefly sketched,but many details are required for a more complete mercially available design programs are either very cum-bersome in operation,requiring several arcane network trans-formations to give realizable filters,or do not have the basic capability.It is interesting that one of the keys to satisfactory design is given in the fundamental 1957paper of Cohn [5].The paper actually describes capacitively coupled LC filters with all-shunt resonators having equal inductances.However,this is somewhat limiting in having all but one of the poles at dc and,as pointed out in [3]and [4],more general filters are required.One of the means of achieving this is to place the desired number of poles at dc and infinity and to design using exact synthesis,which has the advantages of precision and no bandwidth limitations caused by approximations.The best technique for such synthesis involves the transformed variable as described by Orchard and Temes [6].Although this is not a simple topic,it is well worth acquiring the techniques.A much simpler paper describing applications to the design of distributed filters was given by Wenzel [7],and it is recommended that it should be studied first.The techniques described in [7]are almost identical to those for the synthesis of LC filters,the difference being the initial application of a simple Richards’transformation [1,Sec.III].In addition,[7]introduces the unit element or cascaded section of commensu-rate transmission line,which is required for distributed filters and has no counterpart in LC filters.Pseudoelliptic filters are also best designed using exact syn-thesis.One procedure is to synthesize a low-pass prototype,which is then resonated to form a bandpass work trans-formations are used to couple into the filter using,for example,series capacitors,and also to introduce redundant shunt LC el-ements where necessary in order to eliminate “floating nodes.”In some cases,it is convenient to synthesize a bandpass filter di-rectly without the low-pass prototype stage,e.g.,when the poles are asymmetric with respect to the passband,e.g.,when there are poles on just one side of the passband.Pseudoelliptic filters may be designed to give poles by means of cross coupling between nonadjacent resonators,and further discussion is presented in Section III,with particular reference to cascaded-quadruplet (CQ)and cascaded-trisection (CT)fil-ters [10],[11],[39].II.U NIVERSALITY OF UNLOADED,it is instructive to con-sider the definition of that for the series LC resonator shown in Fig.1.The loss of the resonator is due to theresistanceis is defined asthe ratio of the inductor reactance to the series resistance,i.e.,(1)Fig.1.Lumped-element resonator.A similar result applies to the case of a shunt resonator.In either case (series and shunt),at resonance,the energies stored in the magnetic and electric fields are equal.We note that (1)is precisely the definition ofunloadedof an LCresonator is determined primarily by that of the inductor,anditsof any normal (nonsuperconducting)metallic RF cavity is given by a relationship of theformis a linear dimension of thecavity,is usually constant for any given type ofresonator.It is remarkablethatandgigahertzforis of the order 1500–3600for thevarious cavities,withfor copper or silver rather than to the theoreticalvalues,which are almost impossible to realize because of surface imperfections,and a de-rating factor of 0.7has been incorporated in any theoretical calculations.In the case of waveguides,the relationshipbetween retains the same type of proportionality to fre-quency and approximately to a linear dimension.However,theeffectivevalue in a combline filter increases as the ground-plane spacing increases to an appreciable fraction of a wavelength,supporting the propagation of waveguide modes,hence,leading tohigherLEVY et al.:DESIGN OF MICROWA VE FILTERS785 printed circuit filters in microstrip,stripline,and suspendedsubstrate.Acoustic filters are beginning to make inroads intothe market for miniature filters for high-volume production,typically for use in wireless telephones,and details will befound in the papers on regarding microwave acoustics in thisT RANSACTIONS.Superconducting filters are also coming into vogue when theultimate in performance is required,i.e.,taking advantage ofthe extremely high unloaded(3)whereand electrical length(6)and substituting this into(3),we find786IEEE TRANSACTIONS ON MICROWA VE THEORY AND TECHNIQUES,VOL.50,NO.3,MARCH2002with narrow bandwidths at high frequencies,since it is then difficult to control.A good alternative then is to use some form of magnetic loop coupling,which may be adjusted externally. Another external coupling technique that is often very useful is to use“same-sided transformers”[14],which look like extra resonators at each end of the filter,as shown in Fig.2(b),but actually have the role of impedance transformers,and do not contribute to the insertion-loss function of the filter.The filter is lengthened compared with direct tapping,but this may not always be a problem,especially at high frequencies where the dimensions are small,and gives a robust coupling technique. Such filters also have a wide tuning range with no adjustments required to the couplings and rather little change in bandwidth[14].A drawback of combline filters lies in the asymmetry of the insertion loss,which is much weaker on the low-frequency side, especially for broad bandwidths.It is possible sometimes to in-troduce an attenuation pole on the low side of the passband,but this may be difficult with broad bandwidth filters due to disper-sion effects—the cross-coupling capacitance has a linear fre-quency dependence—and the couplings between resonators are large,making cross coupling between nonadjacent resonators mechanically difficult.Other types of distributed filters may then be preferred.When the ground-plane spacing becomes an appreciable frac-tion of a wavelength at mid-band,waveguide modes become the predominant form of coupling,and the filter can no longer be considered as a pure TEM line structure,but rather is an evanes-cent waveguide filter(see[15]and Section III-H of this paper). This type of filter has a very goodunloadedparallel-coupled lines,which alternate between the short-and open-circuited ends,as shown in Fig.3.The equivalent circuit is a cascade of shunt shorted stubs spaced by transmission lines,and unlike combline filters,the lines may be a full90,in order to obtain smaller filters with wider upper rejection bands,comparable to that obtained with combline filters[7].Interdigital filters find most application at higher microwave frequencies above8GHz or so,especially for broad bandwidths. The ideal interdigital filter has characteristics having perfectly arithmetical symmetry,which can be of considerable advantage compared with combline filters.Such symmetry gives better phase and delay characteristics,and it is simpler to designlinear(a)(b)Fig. 3.Interdigital filter.(a)Short-circuited transformer coupling.(b)Open-circuited transformer coupling.phase filters which use cross coupling between nonadjacent res-onators.They have looser inter-resonator couplings compared with combline filters,i.e.,the gaps between resonator bars may be larger and,hence,simpler to produce at high frequencies and wide bandwidths where dimensions become quite small.Inter-digital filters have been designed for such broad bandwidths and high frequencies as8–18,20–28,and28–40GHz,with up to23 resonators.Note that,when very broad bandwidths are speci-fied,it is then difficult in practice(but not in theory)to achieve a return loss of better than15dB or so(0.15-dB ripple level) over the passband.The design theory given by Matthaei in[8,Sec.10.06]is based on wide-band approximations,which give results that are sufficiently accurate for most wide-and narrow-band situations. Any deviations from an ideal response may be corrected by op-timization,or the exact design theories of Wenzel[7],[16]may be used.It is important to mention that the upper stopband of full quarter-wavelength interdigital filters does not extend as high as the third harmonic as frequently stated because of waveguide moding.The first waveguide mode isthe,the waveguide moding occurs at three times the mid-band frequency,i.e.,prior to the first main harmonic passband,which is the fourth harmonic.C.Parallel-Coupled,Hairpin-Line,Patch,and Ring Filters The original type of parallel-coupled-line filters,as depicted in Fig.4,are described in[8,Sec.8.09].They are realized mainly in microstrip or occasionally stripline at higher mi-crowave frequencies since excessive length precludes their economic application in low-loss airline situations.In mi-crostrip,it is necessary to take account of the differing phase velocities between the even and odd modes in the coupled-line regions.There are several papers on this topic,but few appearLEVY et al.:DESIGN OF MICROWA VE FILTERS787Fig.4.Parallel-coupled-line bandpassfilter.Fig.5.Hairpin-line filter.to give simple design procedures that can be applied without excessive work.References may be found in the indexes of past issues of this T RANSACTIONS under the subject of “microstrip filters.”One of the simpler procedures is given in [17],and further discussion may be found in [18]and [19].A very useful paper describing various types of folded par-allel-coupled-line filters,known as hairpin filters,is given in [20].One such type is shown in Fig.5.It is interesting that [20,Fig.5(b)]has some similarity to the very useful ring-type filter introduced by Hong and Lancaster at about the same time [21],although the former has larger capacitive loading to reduce the dimensions.Bandstop filters also may take advantage of the strong cou-pling provided by parallel-coupled lines,as described in [22]and [23].Continuing with the subject of printed circuit bandpass filters,one of the more useful developments since 1984has been the in-troduction of dual-mode patch and ring filters [24].The original paper describes a variety of resonator configurations and filter responses,and includes results for a superconducting filter.This work was followed a few years later by the introduction of ring filters having capacitive gaps [25],structures which lead to enormous flexibility and variety in design.Since the fields near the capacitive gaps are mainly electric,then coupling be-tween two such resonators with these gaps in close proximity is capacitive.The fields on other portions of rings far from the gaps is magnetic,and coupling between these portions in simi-larly magnetic.Hence,both positive and negative couplings are realizable with proximity coupling only,which is a considerable advantage over other types of filter structures that require ca-pacitive probes to realize electric couplings.Another interesting development by the same authors is to use a two-layer structure with both electric and magnetic coupling apertures [26].D.Ceramic Block and Ceramic Puck ResonatorsAn extremely important advance in microwave filters that has taken place since the 1984survey [1]is the development of ce-ramic resonator filters of the following two main types:•ceramic resonator or “puck”filters;•TEM-mode coaxial cavity dielectric-resonator filters.The theory for the first type was actually described quite early,e.g.,in [27],but implementation was delayed for several years because of the lack of availability of suitable dielectric mate-rials having good temperature stability.These were under de-velopment at a number of establishments,and became gener-ally available in the 1980s [28].Ceramic resonator filters of the first type have very low loss and give a substantial reduction in the size of conventional waveguide filters.They may be ei-ther single or dual mode [29],but recent preference is to use single-mode designs because of better temperature stability and somewhat better performance characteristics.There are numerous implementation of filters of the second type and,rather than giving specific references,it is suggested that the reader should research papers by Nishikawa,Wakino,and several co-authors.Much information is available also from the manufacturers of dielectric resonators.The two main ad-vantages of these filters are small size,suitable for use in mo-bile telephones,and very low production cost.They basically consist of coaxial cavities coupled either by series capacitors or by magnetic-field coupling through the dielectric.The theory is usually similar to that for air-line filters,such as combline filters in the magnetically coupled case.In some instances,dielectric may be removed from the coupling region,and an inhomoge-neous structure results,requiring specialized field theory com-putations [30].E.Suspended Substrate Stripline (SSS)DesignsSSS was first described by Rooney and Underkoefler [31]and has proven to be essential to the design of comparatively low-loss very broad-band filters and multiplexers.It is highly suited to the design of pseudoelliptic low-and high-pass filters.An adequate description of the techniques will be found in [1],and perhaps the only subsequent paper in the field that should be added is [19].This is apart from the considerable body of work carried out on micromachined filters,which utilize SSS in the form of a very thin membrane,a topic covered elsewhere in this T RANSACTIONS .F .Waveguide FiltersThe basic paper here is the well-known 1957paper by Cohn [5],which is suitable for narrow-bandwidth rectangular waveguide filters.If broader bandwidth filters are required,then more exact theories should be employed as described in [1].A high-pass filter in waveguide is usually best designed as a broad-band bandpass filter,where the upper stopband is above the desired operating band and,in any case,is often almost nonexistent.In general,this results in a shorter and lower loss filter than one relying on the cutoff frequency of the waveguide.Reference [1]also gives a description of dual-mode wave-guide filters that are widely used in satellites and in some terres-trial systems.Triple-mode filters are mentioned also,but these788IEEE TRANSACTIONS ON MICROWA VE THEORY AND TECHNIQUES,VOL.50,NO.3,MARCH2002 are usually too complicated for other than highly specializedapplications.The main problem is difficulty in tuning and,incommon with dual-mode filters,an inability to tune such filtersover even a narrow tuning range.There has been much literature on filters having highlyoptimum(canonical)elliptic-function characteristics withthe maximum number of attenuation poles,but practicalconsiderations lead one to the preferred use of filters of the cas-caded-synthesis type[10],[11],[39]rather than the canonicaltype.The CQ,CT,or combined CQ/CT filters may require anadditional resonator,but this is almost always justified by theease of tuning.Waveguide low-pass filters are important,being used forharmonic rejection.Waffle-iron filters,as described in[8,Chs.7,15],are often used,and are suitable for very broadpassbands.When the passbands are narrower,then taperedcorrugated low-pass filters[32]are usually preferred sincethey have lower loss,smaller size,and higher power-handlingcapacity,as discussed further in[1].It is important to taperboth broad and narrow dimensions of the waveguide to givehigh rejection of higher order modes in the stopbands.G.Coaxial Low-Pass FiltersThis is another topic dealt in[8,Ch.7],but a more satisfactorydesign technique is to use the very accurate mixed lumped anddistributed theory given in[33],which guarantees good perfor-mance of the filter in the entire operating band,extending to thecutoff frequency.The same theory may be applied to filters de-signed in any medium,such as coaxial line,stripline,microstrip,SSS,or coplanar waveguide.H.Evanescent-Mode FiltersA common assumption when designing combline or interdig-ital filters is that coupling between nonnearest neighbor lines canbe ignored.For configurations in which the ground-plane spacingbecomes larger than about30representing one free-space wavelength at midband),and whenthebandwidthissuchthatthespacingbetweenanytwolinesislessthanabout1.53dB,the device is called a“contiguous”multiplexer.LEVY et al.:DESIGN OF MICROWA VE FILTERS789(a)(b)Fig.6.(a)Illustration of inductive coupling (comb and evanescent filters,condition a)and capacitive coupling,condition b,as in interdigital filters.(b)Coupling equivalent circuit when higher order modes areincluded.Fig.7.N -way reactively connected multiplexer.The frequency separation of channels is called the “guardband.”Frequently a diplexer is termed a duplexer.The distinction is that a duplexer combines a transmitter and a receiver.Thus,a duplexer can be designed as a diplexer,but duplexing can be carried out in other ways,e.g.,using TR devices that reflect high-power signals,but transmit low-power ones.A multiplexer is normally used if a wide spectrum must be accessed equally and instantaneously.Conventionally,multiplexers have had the disadvantage of requiring at least 3-dB excess loss (“crossover”loss)at frequencies common to two channels.Thus,the passband characteristics for contiguous (crossing over at common,but ona flat-loss basis.Although each channel is subject to the addi-tional 3-dB loss,it is essentially constant loss over each channel and,thus,the excess passband loss variation is less than 1dB.Excess loss is defined as that loss not attributable to the in-dividual channel filter rolloff.This power-divider-based com-bining can be extended to triplexers (4.7-dB flat loss),quadru-plexers (6-dB flat loss),etc.Since the loss variation is mini-mized,the overall insertion loss can frequently be made up using post amplifiers (“gain blocks”),displaying flat gain versus fre-quency.Such gain blocks are currently inexpensive and provide flat gain and low noise over wide bandwidths,thus compen-sating for the power-divider losses.Filters can be multiplexed by parallel combination at both ends.For example,if two bandpass filters are diplexed at both input and output,the resulting network provides one input and790IEEE TRANSACTIONS ON MICROWA VE THEORY AND TECHNIQUES,VOL.50,NO.3,MARCH2002Fig.8.Power divider combineddiplexer.Fig.9.Double-diplexed two-channel filter for GPS.one output,has two isolated passbands,essentially attenuating everything else.Such assemblies are useful in systems such as the global positioning system (GPS),which have two or more operating frequencies,with the requirement for isolation be-tween the operating channels and the adjacent cluttered regions of the spectrum (Fig.9).Another approach employs switched selection of filters.Hybrid combinations using multiplexers with power dividers,switches,and amplifiers are now possible.The interactions of these essentially reactive components can cause undesirable degradation of stopbands or passbands,without proper precau-tions.Multiplexer theory is probably best approached by studying lumped-element multiplexers,similarly to the approach sug-gested for the study of stand-alone microwave filters.The constituent filters may also be quantified using susceptance slope parameters and coupling coefficients,as discussed in Section III.The major result in the basic theory concerns the design of a contiguous low-pass/high-pass diplexer.The technique is suc-cinctly described in [36].Other descriptions and references will be found in [1,Sec.X],and there have been more recent devel-opments resulting in multiplexers with many contiguous chan-nels.Much of this work involves computer-aided optimization,frequently combined with field theory to optimize the actual di-mensions.Space precludes detailed description,and the reader is referred to the index issues of this T RANSACTIONS ,these days to be found most conveniently in CD ROM format.However,[37]does provide additional useful detail.V .H IGH -T EMPERATURE S UPERCONDUCTOR (HTS)F ILTERS A.General Properties of HTS Resonator StructuresEarly superconducting devices made use of material such as niobium at liquid helium temperature (4.2K).The requirementfor this very low operating temperature introduced a very se-vere limitation on the practical use of superconductivity.How-ever,in 1986so-called “high-temperature superconductivity”was discovered,which could operate in the 60–80-K range.This made possible adequate cooling with liquid nitrogen,and also the use of small practical electromechanical “cryocoolers.”This has opened up a large new range of applications for supercon-ductivity,and of special interest herein,the design of very com-pact low-loss microwave HTS filters.Most HTS microwave filters in use today are of microstrip form using a thin-film HTS ground plane at the bottom of the substrate and HTS photoeteched circuitry on the top,the sub-strate being mounted in a normal metal housing.HTS filters are not limited to thin-film technology,however,as at least one company has developed a range of nonplanar filters using HTS thick films.It is quite common for very small HTS microstrip resonators toyield’s of 100000or more.Of course,the need for a cryocooler offsets the small size advantage of mi-crostrip HTS filters to some extent,but in many applications,several filters may be placed in a single cryocooler.For example,numerous HTS filter systems for cellular communications use 12filters in a single cryocooler.The substrates used with HTS circuits must have a good crystal lattice match with the HTS in order to obtain a good bond.This plus the need for very low dielectric loss means the number of substrate materials usable are very limited.The most commonly used HTS materials are yttrium-based material YBCO and a thallium-based TBCCO.The commonly used substrate materials are lanthanum aluminateLaAlO),and sapphire(buffer layer to provide a lattice match.Thesesubstrates are usually available in only relatively small sizes with diameters of only 2or 3in.This limits the size of HTSLEVY et al.:DESIGN OF MICROWA VE FILTERS 791circuits,as does the size of the cryocooler,which,of course,is kept as small as is feasible.An important property of HTS circuits,besides their very low loss,is that when the current density in the HTS is raised to a certain level,nonlinear effects begin to appear.These cause the conductivity to decrease with increasing current density,thus lowering theresonatorHTS circuits.For practical reasons,most HTS microstrip circuits use normal metal cover plates,and it is highly desirable to minimize any currents induced in the cover by use of circuitry that tends to keep the fields confined to the substrate or its near vicinity.For example,a microstrip meander line tends to confine the fields much better than does a line in the form of a loop or spiral.Due to the nonlinear effects in HTS,planar HTS filters are useful mainly for low-power applications,say,of the order of a milliwatt or less.However,if relatively large nonplanar HTS structures are used,considerably higher power can be han-dled.For example,one manufacturer has marketed a nonplanar thick-film HTS power combiner for relatively high-power cel-lular applications (power of the order of tens of watts).Another approach that uses HTS thin-film technology for relatively high powers is to incorporate very low-loss dielectric material in such a way that most of the energy is carried in regions away from the HTS.Resonators have been demonstrated that use a circular puck of sapphire spaced between two parallel thin-film HTS ground planes.This keeps the energy confined with most of it in the sapphire,and the fields are relatively weak near theHTS.’s in HTS,high-power resonators isimportant for additional reasons besides permitting sharp filter cutoffs.If too much energy is dissipated in the resonator,the resonator will heat up,and the superconducting operation may be lost.)This type of resonator has many spurious resonances so it would only be of interest for filter applications where the unwanted signals are quite close to the passband.Also,because of practical size limitations on the thin-film ground planes and the puck,this approach is probably of interest mainly forrelatively high frequencies (such as 10GHz)rather than,say,cellular frequencies of around 800MHz or so.As can be seen,the design of high-quality HTS filters can be a very challenging task,but they offer quite attractive advantages for some system applications where veryhigh-792IEEE TRANSACTIONS ON MICROWA VE THEORY AND TECHNIQUES,VOL.50,NO.3,MARCH2002[14]I.C.Hunter and J.D.Rhodes,“Electronically tunable microwave band-pass filters,”IEEE Trans.Microwave Theory Tech.,vol.MTT-30,pp.1354–1360,Sept.1982.[15]R.Levy,H.-W.Yao,and K.A.Zaki,“Transitional combline/evanescentmode microwave filters,”IEEE Trans.Microwave Theory Tech.,vol.45, pp.2094–2099,Dec.1997.[16]R.J.Wenzel,“Exact theory of interdigital bandpass filters and relatedcoupled structures,”IEEE Trans.Microwave Theory Tech.,vol.MTT-13,pp.559–575,Sept.1965.[17] B.Easter and K.A.Merza,“Parallel-coupled-line filters for inverted-mi-crostrip and suspended-substrate MIC’s,”in11th Eur.Microwave Conf.Dig.,September1981,pp.164–167.[18] A.Riddle,“High performance parallel coupled microstrip filters,”in IEEE MTT-S Int.Microwave Symp.Dig.,vol.I,May1988,pp.427–430.[19]R.Levy,“New equivalent circuits for inhomogeneous coupled lines,with synthesis applications,”IEEE Trans.Microwave Theory Tech.,vol.36,pp.1087–1094,June1988.[20]G.L.Matthaei,N.O.Fenzi,R.Forse,and S.Rohlfing,“Hairpin-combfilters for HTS and other narrow-band applications,”IEEE Trans.Mi-crowave Theory Tech.,vol.45,pp.1226–1231,Aug.1997.[21]J-S.Hong and ncaster,“Couplings of microstrip squareopen-loop resonators for cross-coupled planar microwave filters,”IEEE Trans.Microwave Theory Tech.,vol.44,pp.2099–2109,Nov.1996. [22] B.M.Schiffman and G.L.Matthaei,“Exact design of band-stopmicrowave filters,”IEEE Trans.Microwave Theory Tech.,vol.MTT-12,pp.6–15,Jan.1964.[23]H.C.Bell,“L-resonator bandstop filters,”IEEE Trans.MicrowaveTheory Tech.,vol.44,pp.2669–2672,Dec.1996.[24]J.A.Curtis and S.J.Fiedziuszko,“Miniature dual mode microstrip fil-ters,”in IEEE MTT-S Int.Microwave Symp.Dig.,vol.II,June1991,pp.443–446.[25]J-S.Hong and ncaster,“Theory and experiment of novel mi-crostrip slow-wave open-loop resonator filters,”IEEE Trans.Microwave Theory Tech.,vol.45,pp.2358–2365,Dec.1997.[26],“Aperture-coupled microstrip open-loop resonators and theirapplications to the design of novel microstrip bandpass filters,”IEEE Trans.Microwave Theory Tech.,vol.47,pp.1848–1855,Sept.1999.[27]S.B.Cohn,“Microwave filters containing high-Q dielectric resonators,”IEEE Trans.Microwave Theory Tech.,vol.MTT-16,pp.218–227,Apr.1968.[28]J.K.Plourde and C-L.Ren,“Application of dielectric resonators inmicrowave components,”IEEE Trans.Microwave Theory Tech.,vol.MTT-29,pp.754–770,Aug.1981.[29]S.J.Fiedziuszko,“Dual-mode dielectric resonator loaded cavity filters,”IEEE Trans.Microwave Theory Tech.,vol.MTT-30,pp.1311–1316, Sept.1982.[30] A.Fukasawa,“Analysis and composition of a new microwave filter con-figuration with inhomogeneous dielectric medium,”IEEE Trans.Mi-crowave Theory Tech.,vol.MTT-30,pp.1367–1375,Sept.1982. [31]J.P.Rooney and L.M.Underkofler,“Printed circuit integration of mi-crowave filters,”Microwave J.,vol.21,pp.68–73,Sept.1978. [32]R.Levy,“Tapered corrugated waveguide lowpass filters,”IEEE Trans.Microwave Theory Tech.,vol.MTT-21,pp.526–532,Aug.1973. [33],“A new class of distributed prototype filters,with applications tomixed lumped/distributed component design,”IEEE Trans.Microwave Theory Tech.,vol.MTT-18,pp.1064–1071,Dec.1970.[34]R.V.Snyder,“Inverted resonator evanescent mode filters,”in IEEEMTT-S Int.Microwave Symp.Dig.,vol.2,San Francisco,CA,1996, pp.465–468.[35],“Present and future filter design philosophy:Paradigm shift inprogress,”presented at the Proc.Eur.Microwave Conf.Filters Work-shop,Paris,France,Sept.2000.[36]R.J.Wenzel,“Application of exact synthesis methods to multichannelfilter design,”IEEE Trans.Microwave Theory Tech.,vol.MTT-13,pp.5–15,Jan.1965.[37]M.Golio,The RF and Microwave Handbook,R.V.Snyder,Ed.BocaRaton,FL:CRC Press,2001,ch.5.9.[38]R.R.Mansour,“Microwave superconductivity,”IEEE Trans.Mi-crowave Theory Tech.,vol.50,pp.750–759,Mar.2002.[39]R.Levy,“Corrections to‘Direct synthesis of cascaded-quadruplet(CQ)filters’,”IEEE Trans.Microwave Theory Tech.,vol.45,p.1517,Aug.1996.Ralph Levy(SM’64–F’73–LF’99)received the B.A.and M.A.degrees in physics from Cambridge Uni-versity,Cambridge,U.K.,in1953and1957,respec-tively,and the Ph.D.degree in applied sciences fromLondon University,London,U.K.,in1966.From1953to1959,he was with GEC,Stanmore,U.K.,where he was involved with microwavecomponents and systems.In1959,he joined MullardResearch Laboratories,Redhill,U.K.,where hedeveloped a widely used technique for accurateinstantaneous frequency measurement using several microwave discriminators in parallel known as digital IFM.This electronic countermeasures work included the development of decade bandwidth directional couplers and broad-band matching theory.From1964to1967, he was a member of the faculty of The University of Leeds,Leeds,U.K., where he carried out research in microwave network synthesis,including distributed elliptic function filters and exact synthesis for branch-guide and multiaperture directional couplers.In1967,he joined Microwave Development Laboratories,Natick,MA,as Vice President of Research.He developed practical techniques for the design of broad-band mixed lumped and distributed circuits,such as tapered corrugated waveguide harmonic rejection filters,and the synthesis of a variety of microwave passive components.This included the development of multioctave multiplexers in SSS,requiring accurate modeling of inhomogeneous stripline circuits and discontinuities.From1984to1988, he was with KW Microwave,San Diego,CA,where he was mainly involved with design implementations and improvements in filter-based products.From August1988to July1989,he was with Remec Inc.,San Diego,CA,where he continued with advances in SSS components,synthesis of filters with arbitrary finite frequency poles,and microstrip filters.In July1989,he became an independent consultant and has worked with many companies on a wide variety of projects,mainly in the field of passive components,especially filters and multiplexers.He has authored approximately70papers and two books, and holds12patents.Dr.Levy has been involved in many IEEE Microwave Theory and Tech-niques Society(IEEE MTT-S)activities,including past editor of the IEEE T RANSACTIONS ON M ICROWA VE T HEORY AND T ECHNIQUES(1986–1988). He was chairman of the Central New England and San Diego IEEE MTT-S chapters,and was vice-chairman of the Steering Committee for the1994IEEE MTT-S International Microwave Symposium(IMS).He was the recipient of the1997IEEE MTT-S CareerAward.Richard V.Snyder(S’58–M’63–SM’80–F’97)re-ceived the B.S.degree from Loyola-Marymount Uni-versity,Los Angeles,CA,the M.S.degree from theUniversity of Southern California,Los Angeles,andthe Ph.D.degree from the Polytechnic Institute ofNew York,Brooklyn.He is currently the President and founder of the RSMicrowave Company Inc.,Butler,NJ,a well-known20-year-old manufacturer of RF and microwave fil-ters.He teaches filter and network courses and ad-vises Ph.D.candidates as an Adjunct Professor at the New Jersey Institute of Technology,Newark,NJ.His professional experience also includes having been a Research Engineer at ITT-Gilfillan,the Chief En-gineer for Merrimac Industries,the Vice-President of FEL,where he ran the Microwave Division,and the Chief Engineer for Premier Microwave.He has authored or co-authored over60papers on the subject of filters and couplers. He holds14patents.His current research areas include electromagnetic simu-lation as applied to filters and networks,dielectric resonators,and active filter networks.He is on the Editorial Board of Microwave Journal.Dr.Snyder was the North Jersey Section chairman and a14-year chapter chairman for the IEEE Microwave Theory and Techniques Society(IEEE MTT-S)and the IEEE Antennas and Propagation Society(IEEE AP-S).He is a reviewer for the IEEE T RANSACTIONS ON M ICROW A VE T HEORY AND T ECHNIQUES,the IEEE M ICROW A VE AND G UIDED W A VE L ETTERS,and other IEEE and IEEE MTT-S publications.His professional involvement also includes IEEE MTT-S Administrative Committee(AdCom)special assign-ments and various IEEE MTT-S chapter lectures on the subject of filters and networks.He is general chairman of the IEEE MTT-S International Microwave Symposium(IMS),which is to be held in Philadelphia,PA,in2003.He served as Standards chairman for the IEEE MTT-S AdCom and currently serves as chairman of the IEEE MTT-8(the IEEE MTT-S Technical Committee charged with oversight of filters and passive components).He has also served as the North Jersey Section EDS/C&S chair,METSAC chairman,and as an organizer of tutorial sessions for Electro.He was a two-time recipient of the Region1 Award.He was recipient of a Best Paper Award presentation notice at the1991 MTT-S IMS.He was also a recipient of the2000IEEE Millennium Medal.。

微波无损检测外文书籍

微波无损检测外文书籍Microwave Non-Destructive Testing: A ReviewAbstract:Microwave non-destructive testing (MNDT) is a non-invasive technique that uses microwave radiation to evaluate the internal structure and qualityof materials without causing any damage. In this review, we aim to provide a comprehensive overview of the current state of MNDT techniques discussed in existing foreign literature. We will explore the principles, applications, advantages, and challenges associated with microwave non-destructive testing.1. IntroductionMicrowave non-destructive testing (MNDT) has gained significant attention in recent years due to its ability to provide accurate and reliable results in various fields, including aerospace, construction, and medicine. This technique works by emitting microwave radiation towards the material of interest and analyzing the scattered waves to determine its internal properties. Unlike traditional destructive testing methods, MNDT allows for real-time evaluation without causing any harm to the tested material.2. Principles of MNDTMicrowave non-destructive testing relies on the interaction between microwaves and the material being tested. The dielectric properties, such as permittivity and permeability, play a crucial role in determining the behavior of microwaves within the material. By analyzing the reflection, transmission,and absorption of microwaves, MNDT techniques can provide valuable information about the material's structure, composition, and defects.3. MNDT Techniques and InstrumentsThere are various MNDT techniques and instruments available, each with its unique advantages and limitations. Some commonly used techniques include microwave imaging, microwave tomography, and microwave resonance. Microwave imaging allows for the visualization of internal structures, while microwave tomography provides three-dimensional images of the material. Microwave resonance techniques measure the resonant frequencies to detect hidden defects or inconsistencies within the material.4. Applications of MNDTThe versatility of MNDT techniques enables their applications in a wide range of industries. In the aerospace industry, MNDT plays a critical role in inspecting composite materials used in aircraft construction, ensuring structural integrity and safety. In the field of medicine, microwave non-destructive testing is utilized for the detection of tumors and abnormalities in tissues. Additionally, MNDT techniques find applications in evaluating the quality of construction materials, such as concrete and asphalt.5. Advantages and ChallengesOne of the main advantages of microwave non-destructive testing is its ability to provide rapid and non-invasive evaluations. This significantly reduces the time and cost associated with conventional destructive testing methods. Moreover, MNDT can penetrate through several centimeters of material, enabling the detection of defects hidden beneath the surface.However, MNDT also faces challenges such as limited resolution and difficulty in interpreting complex data. Ongoing research aims to overcome these challenges and further enhance the capabilities of microwave non-destructive testing.6. ConclusionMicrowave non-destructive testing has emerged as a valuable technique for evaluating the internal properties and quality of materials. Its non-invasive nature, combined with its applications in various industries, makes MNDT an indispensable tool for quality assurance and defect detection. Although challenges exist, ongoing advancements aim to improve MNDT techniques and instruments, opening doors for even wider applications in the future.References:(References have been omitted as per the given instructions)。

Conventional wet impregnation versus microwave-assisted

RESEARCH PAPERConventional wet impregnation versus microwave-assisted synthesis of SnO 2/CNT compositesSarah Motshekga •Sreejarani K.Pillai •Suprakas S.RayReceived:4May 2010/Accepted:16September 2010ÓSpringer Science+Business Media B.V.2010Abstract Carbon nanotubes decorated with SnO 2nanoparticles were prepared by conventional and microwave-assisted wet impregnation.The compos-ites were thoroughly characterized by X-ray dif-fraction,Raman spectroscopy,BET-surface area measurement,Scanning and transmission electron microscopy.The XRD studies revealed the formation of tetragonal phase of SnO 2.The microwave method produced CNTs heavily decorated with SnO 2nano-particles with average size 5nm in a total reaction time of 10min because of the rapid volumetric heating.DC conductivity increased signiﬁcantly for the nanocomposite samples when compared with thepure CNTs.In electrical conductivity properties,sample prepared by microwave method was found to be superior to the one prepared by conventional procedure due to homogeneous distribution of nanoparticles.Keywords Wet impregnation ÁMicrowave synthesis ÁSnO 2nanoparticles ÁCNTs ÁNanomaterialsIntroductionCarbon nanotubes (CNTs)have remained in the forefront of intense research for more than a decade,due to their exceptional physical,chemical,and electronic properties that have been inherited from the parent in-plane graphite (Dresselhaus et al.2001).Their small dimensions,closed topology,and lattice helicity have enabled nanotubes to inﬂuence broad areas of science and technology,ranging from super strong nanocomposites to nanoelectronics (Endo et al.2008;Balasubramanian and Burghard 2008;Sharma and Ahuja 2008).A number of modiﬁcations by functionalizing,doping or coating,have been suggested to further improve the properties and optimize the use of CNTs in applications (Kiang et al.1999;Han et al.2003;Joanne et al.2002).It has been reported that CNTs can be modiﬁed by means of coating or ﬁlling with metal colloids (Zhang et al.S.Motshekga ÁS.K.Pillai (&)ÁS.S.Ray DST/CSIR Nanotechnology Innovation Centre,National Centre for Nano-Structured Materials,Council for Scientiﬁc and Industrial Research,Pretoria 0001,Republic of South Africa e-mail:skpillai@csir.co.zaS.MotshekgaDepartment of Chemical and Metallurgical Engineering,Tshwane University of Technology,Pretoria 0001,Republic of South AfricaS.S.RayDepartment of Chemistry,Faculty of Naturaland Agricultural Sciences,University of the Free State (Qwaqwa Campus),Phuthaditjhaba 9866,Republic of South AfricaJ Nanopart ResDOI 10.1007/s11051-010-0098-92000;Han et al.2004;Chen et al.2004)and oxides (Jitianu et al.2004;Zhao and Gao2004;Fu et al. 2004).Among the materials functionalized by CNTs, there were particular intensive attentions on SnO2 because of its unique properties such as high optical transparency,electrical conductivity,and chemical sensitivity,which made it an attractive material for application in solar cells,biosensors,electrode mate-rials for Li-ion batteries,supercapacitors,electro-catalytic decomposition of organic wastewater,ﬁeld effect transistors,catalysis,and gas-sensing(Han et al.2003;Wei et al.2004;Liu et al.2006).The previous reports indicate that the detection of toxic gases at ambient temperature can be highly improved by dispersing adequate quantity of metal or semi-conducting oxide on to T have been functionalized with Pd,Pt,Rh,and Au metals for CO,H2,H2S,NH3,and NO2gas detection by integrating an array(Star et al.2006).Hybrid layers based on titania and CNTs also have been processed for detecting O2traces at high sensitivity(Llobet et al.2008).Recently,it is reported that the metal-CNT hybrid materials,synthesized by inﬁltrating SWCNTs with the transition metals Ti,Mn,Fe,Co, Ni,Pd or Pt showed extremely high sensitivity to trace ethanol levels(Brahim et al.2009).The preparation of metal oxide/CNT composites is still largely based on conventional catalyst prepara-tion techniques,such as wet-chemical(Han et al. 2003;Zhao and Gao2004;2009),sol–gel(Gong et al. 2008),gas-phase(Ganhua et al.2009;Yanbao et al. 2009),and supercriticalﬂuid(An et al.2007) methods.Microwave-irradiated synthesis of compos-ite materials is a new promising technique due to its rapid heating and penetration.The advantage of this method over the conventional synthetic methods is the improved kinetics of the reaction generally by one or two orders of magnitude,which may result in narrow distribution of particle size(Chen et al.2007; Liu and Huang2005).In this paper,we report a comparison between conventional and microwave-aided wet impregnation techniques for depositing SnO2nanoparticles on CNTs.The resulting composites were characterized by scanning electron microscopy(SEM),transmis-sion electron microscopy(TEM),X-ray diffraction (XRD),Raman spectroscopy,Fourier transform infrared spectroscopy(FT–IR),BET surface area and Electrical conductivity measurements.ExperimentalMaterialsMWCNTs(inner diameter,7–10nm;outer diameter, 20nm;length,0.5–500l m)used in this study were purchased from Sigma-Aldrich.MWCNTs(from now throughout the text described as CNTs)were more than95%pure as checked by SEM,EDS,and TEM.All reagents used in this study were purchased from Sigma-Aldrich and were used as received.MethodsConventional wet impregnationFive-hundred milligrams of CNTs was reﬂuxed with 5M HNO3(10mL/10mg)at120°C for2h,ﬁltered and then washed with distilled water until the pH of the solution was neutral.The CNTs were then dried at 110°C for12h.Subsequently,10g of tin(II) chloride(SnCl2)was dissolved in400ml of distilled water and3.5ml of concentrated HCl(37%)was added.The acid-treated CNTs were dispersed in the above solution.This mixture was sonicated for3min using a high-power ultrasonicﬁnger and then stirred magnetically for1h at room temperature.The precipitate was then separated from the mother liquor by centrifugation and was washed with distilled H2O for several times,and dried at110°C for12h.The ﬁnal product was calcined at500°C for2h. Microwave-assisted wet impregnationFive-hundred milligrams of CNTs was reﬂuxed with 5M HNO3(10mL/10mg)at120°C for5min in a microwave reactor(Perkin Elmer microwave reaction system-Multiwave3000)at a power setting of 500W.The solution wasﬁltered and washed with distilled water until the pH of the solution was neutral.The CNTs were then dried at110°C for 12h.In the second step,10g of tin(II)chloride (SnCl2)was dissolved in400mL of distilled water and3.5mL of concentrated HCl(37%)was added. The CNTs were added to the above solution and reﬂuxed in the microwave reactor for(Anton Paar Multiwave3000)5min at500W and60°C.The precipitate was then separated from the mother liquor by centrifugation and was washed with distilled H2OJ Nanopart Resfor several times,and dried at110°C for12h.The ﬁnal product was calcined at500°C for2h. CharacterizationThe morphology of the samples was investigated by a JEOL7500FESEM at2kV accelerating voltage. The samples were sputter coated with carbon to avoid charging.TEM analysis was conducted on a JEOL 2100F TEM instrument,operated at200kV.The powder sample was sonicated in methanol for5min, followed by depositing the solution on a Cu-grid with holey carbonﬁlm.The crystalline phases of the samples were determined by X-ray diffraction(PAn-alytical XPERT-PRO diffractometer)measurement, using Niﬁltered CuK a radiation(k=1.5406A˚), with a variable slit at35kV,50mA.The Raman spectra of samples were recorded by a Jobin–YvonT64000and LabRam HR800.For these measure-ments an excitation wavelength of514.5nm with power setting of1.2mW was used.Simultaneous determination of BET(Brunauer,Emmett,and Teller)surface area and total pore volume of the samples were achieved in a Micromeritics TRISTAR 3000surface area analyzer by the low-temperature N2 adsorption method.Prior to analysis,the samples were degassed at120°C overnight(12h)under a continuousﬂow of N2gas to remove adsorbed contaminants from the surface and pores of the CNTs.FT-IR spectra were recorded using a Perkin Elmer Spectrum100spectrometer equipped with a germanium crystal.For the electrical conductivity measurements,the powder samples were pressed into disc(1cm diameter and0.2cm thickness)and the resistance was obtained at room temperature with a Keithley4200SCS four-point probe instrument with applied current of0.001mA.The resistivity and hence the conductivity were then determined from the resistance and the sample thickness.Results and discussionTo conﬁrm the formation of SnO2nanoparticles on CNTs,and check the crystalline phases,the prepared samples were analyzed by XRD and the diffracto-grams are presented in Fig.1.All the samples show peaks of C(002)and C(100)phases with d002values of0.34nm characteristic of CNTs.Apart from these peaks,intense peaks corresponding to tetragonal phase of SnO2(JCPDSﬁle No.88–0287)are clearly visible in the composite samples.The C(002)peaks of CNTs appear to be shifted in the composite samples which shows the interaction of SnO2nano-particles with CNTs.The average crystallite size of the nanoparticles was conﬁrmed using the Scherrer equation:d=K kb Cos h,where d is the mean crystallite size,K is a grain shape-dependent constant(0.9),k is the wavelength of the incident beam,h is the Bragg reﬂection angle,and b is the full-width half-maxi-mum.The crystallite sizes estimated from the XRD spectra using the Scherrer equation are2nm and 3nm,respectively,for composites prepared by conventional and microwave-assisted wet impregna-tion methods.SEM image of the pure CNTs is shown in Fig.2a. The surface of pristine CNTs appears to be clean and smooth from the image.The deposition of SnO2 nanoparticles along the sidewalls of CNTs is clearly evident for the samples prepared by conventional (Fig.2b)and microwave methods(Fig.2c).CNTs with open tips are clearly visible in the images of functionalized samples which may be due to the nitric acid oxidation of the nanotubes prior to the SnO2 loading.It is worth noting that the CNTs exhibit no obvious length decrease or damage after surface functionalization.On the other hand,the roughening deposition of SnO2nanoparticles on the surface of the tubes is observed to be more(tubes look as if heavilyJ Nanopart Rescoated)for the microwave sample.The SnO 2nano-particles in the composite prepared by microwave method appear to be slightly bigger when comparedwith the particles in the conventionally synthesized composite.Figure 3a–c represent the typical HRTEM images of pure and SnO 2/CNT samples.The corresponding low-magniﬁcation images are given in the inset.It can be clearly seen that the pure CNTs (Fig.2a)have very clean and smooth surface,unlike the composite samples.SnO 2nanoparticles of size 2–4nm are observed on the surface and inside the tubes for the composite prepared by wet impregnation (refer Fig.2b).The observed nanoparticles inside the tubes could be due to tips of the tubes that were opened by nitric acid oxidation.In comparison with the con-ventional method,microwave route gives CNTs that are densely coated with SnO 2nanoparticles layer by layer which may be due to the improved kinetics of the reaction through rapid volumetric heating.The particles with average size 3–5nm are found to be distributed around and inside of the nanotubes though some agglomerations are found along the surface of the nanotubes in this case.The TEM observations on sizes of SnO 2nanoparticles are in line with XRD and SEM results.Figure 4shows the Raman spectra recorded for the pure CNTs and the corresponding SnO 2/CNT hetero-structures.For all the samples,the D band occurs around 1350cm -1while G band is observed at 1585cm -1which is typical of CNTs (‘G’for graphitic band and ‘D’for defect band).The intensity ratios (I G /I D )calculated for the pure,conventional,and microwave samples were 0.64,0.80,and 0.94,respectively.The explanation for the observed I G /I D ratio increase in composite samples might be the enhancement of atomic ordering of crystallinity of the CNTs after it is ﬁlled with SnO 2nanoparticles (Yanbao et al.2009).FTIR spectroscopy can be used to detect these functional groups created on the CNT surface.It is reported that chemical oxidation using HNO 3can create various functional groups such as –COOH,–OH,and –C=O at the defect sites of the nanotubes wall,which act as nucleation sites for metal clusters (Ebbesen et al.1996).The FTIR spectra obtained for various samples are given in Fig.5.The peaks at 1976cm -1and 2160cm -1correspond to the pres-ence of the CNTs are apparent in all the samples.Though we could not ﬁnd the characteristic O–H peaks of –COOH group,the peaks which are observed from 1690cm -1to 1760cm -1indicatedFig.2SEM micrographs of a pure CNTs b SnO 2/CNT composite prepared by conventional wet impregnation c SnO 2/CNT composite prepared by microwave-assisted wet impregnationJ Nanopart Resthe formation of C=O groups and hence the oxidation of CNTs(Tuinstra and Koenig1970).The typical peaks appearing around500–700cm-1in the mod-iﬁed samples are attributed to the Sn–O bonds of SnO2nanoparticles on CNTs(Ebbesen et al.1996).The BET surface areas of CNT samples are given in Table1.The pure CNT sample has low surface area when compared with the functionalized samples.Fig.3HRTEM images of a pure CNTs b SnO2/CNT composite prepared by conventional wet impregnation c SnO2/CNT composite prepared by microwave-assisted wet impregnation. The insets show corresponding low-magniﬁcation images cJ Nanopart ResThe surface area signiﬁcantly increases for the samples prepared by the conventional and micro-wave methods.The increase is attributed to the introduction of smaller sized tin oxide nanoparticles on to the CNT surface(Xie and Varadan2005). The heavy coating of the CNT by relatively bigger SnO2particles can be a reason for the nominal surface area decrease obtained for the microwave sample.The room temperature DC conductivity of the samples was measured using a four-point-probe method by supplying a current(I)of0.001A through the two outer probes and measuring the correspond-ing voltage drop(V)through the two inner probes. The resistance changes as a function of probe spacing (s=0.127cm)and the resistivity q is given by the equation q=2p s(V/I),where the thickness of the ﬁlm t is greater than the probe spacing.The conductivity is then calculated as r=1/q.The conductivity values of various samples obtained from four-point probe measurements are presented in Table1.The conductivity increases appreciably for the composite samples.For example,the DC con-ductivity increases from2.02910-2S/cm for the pure CNTs to 3.20910-1S/cm(average ofﬁve independent measurements with a maximum error of 7%)for the nanocomposite prepared by the conven-tional method,a10-time increase of in the electrical conductivity whereas for the composite prepared by microwave method,the increase is100-times when compared with the unmodiﬁed sample.The result indicates that the nanoparticles made an effective contact on CNT surface which reduced the resistance to the conduction of electrons.Although both prep-aration methods are effective for surface functional-ization with SnO2particles,the microwave irradiation is found to be more advantageous in enhancing the inherent DC conductivity property of the CNTs support material.ConclusionsIn the present work,a comparison was made between conventional and microwave synthesis of SnO2/CNT nanocomposites.SEM and TEM observations show the heavy coating of CNTs by SnO2nanoparticles in a total reaction time of10min by microwave method. The increase I G/I D ratio in Raman spectra in the case of nanocomposite samples is attributed to the increase in atomic ordering of the CNTs due to the deposition of nanoparticles on the outer and inner surfaces of the tubes which may compensate for the defects.The improvement of DC conductivity of CNTs after nanocomposite formation with SnO2 nanoparticles shows their potential to be used in optoelectronic devices.The DC electrical conductiv-ity of the composite prepared by microwave method is found to be superior to the one prepared by conventional method.Acknowledgment Authors wish to thank DST and CSIR, South Africa,for theﬁnancial support.ReferencesAn G,Na N,Zhang X,Miao Z,Miao S,Ding K,Liu Z(2007) SnO2/carbon nanotube nanocomposites synthesized in supercriticalﬂuids:highly efﬁcient materials for use as a chemical sensor and as the anode of a lithium-ion battery.Nanotechnology18:435707–4357013.doi:10.1088/0957-4484/18/43/435707Balasubramanian K,Burghard M(2008)Electrochemically functionalized carbon nanotubes for device applications.J Mater Chem18:3071–3083.doi:10.1039/b718262g Brahim S,Colbern S,Gump R,Moser A,Grigorian L(2009) Carbon nanotube-based ethanol sensors.Nanotechnology 2:235502–235509.doi:10.1088/0957-4484/20/23/235502 Chen WX,Lee JY,Liu ZL(2004)Preparation of Pt and Pt–Ru nanoparticles supported on carbon nanotubes by micro-wave-assisted heating polyol process.Mater Lett58: 3166–3169.doi:10.1016/j.matlet.2004.06.008Table1BET surface area measurements and DC conductivity of pure CNTs and SnO2/CNT composite samples prepared by conventional and microwave wet impregnation methodsSamples BET surfacearea/m2/g Microporevolume/cm3/gPoresize/nmElectricalconductivity/S/cmPure CNTs107.580.4913.51 2.02910-2 SnO2/CNT(Conventional)135.610.5014.64 3.20910-1 SnO2/CNT(Microwave)129.690.3611.53 4.01J Nanopart ResChen YH,Iqbal Z,Mitra S(2007)Microwave-induced con-trolled puriﬁcation of single walled carbon nanotubes without sidewall functionalization.Adv Funct 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Sammaynaiken R,Sham TK(2009)An X-ray absorption, photoemission,and Raman study of the interaction between SnO2nanoparticle and carbon nanotube.J Phys Chem C113:6114–6117.doi:10.1021/jp810639yJ Nanopart Res。

Microwave-Sintering-of-Metals

Microwave Sintering of MetalsTopics CoveredBackgroundOverviewMicrowave Heating of MetalsMicrowave vs.Conventional HeatingWhich Metals can be Microwave Sintered?Which Metals have been Microwave Sintered?Microwave Sintering DevicesPotential for Microwave Sintering of MetalsWhy does Microwave Sintering Produce better Properties compared to Conventional Processing?Microwave Sintering MechanismsBackgroundMicrowave energy has been in use for a variety of applications for over50years.Some of the early applications include communication,navigation and drying of food items.At present,industrial uses of microwaves include wood processing,vulcanisation of rubber,meat tempering,and medical therapy.In the past two decades,the remarkable success of domestic microwave ovens has revolutionised home cooking.OverviewThe use of microwaves in ceramic processing is a relatively recent development.They can be applied effectively and efficiently to heat and sinter ceramic objects.The most recent development in microwave applications is in sintering of metal powders,a surprising application,in view of the fact that bulk metals reflect microwaves. However,reflection by a metal occurs only if it is in a solid,nonporous form and is exposed to microwaves at room temperature.Metal in the form of powder will absorb microwaves at room temperature and will be heated very effectively and rapidly.This technology can be used to sinter various powder metal components,and has produced useful products ranging from small cylinders,rods,gears and automotive components in30-90min.Microwave Heating of MetalsMicrowave heating and sintering is fundamentally different from the conventional sintering,which involves radiant/resistance heating followed by transfer of thermal energy via conduction to the inside of the body being processed.Microwave heating is a volumetric heating involving conversion of electromagnetic energy into thermal energy,which is instantaneous,rapid and highly efficient.The microwave part of the electromagnetic spectrum corresponds to frequencies between300MHz and300GHz. However,most research and industrial activities involve microwaves only at2.45GHz and915MHz frequencies. Based on their microwave interaction,most materials can be classified into one of three categories-opaque, transparent and absorbers.Bulk metals are opaque to microwave and are good reflectors-this property is used in radar detection.However,powdered metals are very good absorbers of microwaves and heat up effectively, with heating rates as high as100°C min-1.Most other materials are either transparent or absorb microwaves to varying degrees at ambient temperature.The degree of microwave absorption,and consequently of heating, changes dramatically with temperature.Microwave vs.Conventional HeatingThe use of microwave energy for materials processing has major potential,and real advantages over conventional heating.These include:· Time and energy savings· Rapid heating rates· Considerably reduced processing time and temperature· Fine microstructures and hence improved mechanical properties and better product performance· Lower environmental impact.Which Metals can be Microwave Sintered?Until recently,microwave heating has been applied to sinter only oxide ceramics and semi-metals like carbides and nitrides.However,our research reveals that in powdered form,virtually all metals,alloys,and intermetallics will couple and heat efficiently and effectively in a microwave field,and their green parts will produce highly sintered bodies with improved mechanical properties.For example,in our exploratory experiments we tried two common commercial steel compositions,namely Fe-Ni-C(FN208)and Fe-Cu-C(FC208).These formed highly sintered bodies in a total cycle time of about90min at temperature range of1100-1300°C with a soaking time of 5-30min in forming gas(a mixture of N2and H2)atmosphere.Mechanical properties such as the modulus ofrupture(MOR)and hardness of microwave processed samples were significantly higher than the conventional samples-in the case of FN208,the MOR was60%higher.The densities of microwave processed samples were close to the theoretical densities,and the net shape of the green body was preserved without significant dimensional changes.Which Metals have been Microwave Sintered?Many commercial powder-metal components of various alloy compositions,including iron and steel,copper, aluminum,nickel,molybdenum,cobalt,tungsten,tungsten carbide,tin,and their alloys have been sintered using microwaves,producing essentially fully dense bodies.Figure1illustrates some of the metallurgical parts processed using microwave technology.The biggest commercial steel component that has been fully sintered in our system so far is an automotive gear of10cm in diameter and about2.5cm in height.Figure1.Metallic parts produced by microwave sintering such as gears cylinders,rods and discs. Microwave Sintering DevicesA typical microwave sintering apparatus operates at a2.45GHz frequency with power output in the range of1-6 kW.The sintering chamber consists of ceramic insulation housing(batch system)or an alumina tube insulated with ceramic insulation from outside,figure2.The primary function of the insulation is to preserve the heat generated in the workpiece.The temperatures are monitored by optical pyrometers,IR sensors and/or sheathed thermocouples placed close to the surface of the sample.The system is equipped with appropriate equipment to provide the desired sintering atmosphere,such as H2,N2,Ar,etc,and is capable of achieving temperatures up to1600°C.Figure2.Schematic of a microwave sintering furnace.The technology can be easily commercialised by scaling up the existing microwave system or designing a continuous system capable of sintering parts of various shapes and sizes.Potential for Microwave Sintering of MetalsThe implications of microwave sintering of metals are obvious in the field of powder metal technology.Metal powders are used in a diverse range of products and applications in various industries,including the automotive industry,aerospace,and heavy machinery.The challenging demands for new and improved processes and materials of high integrity for advanced engineering applications require innovation and new technologies.Finer microstructures and near-theoretical densities in special powder metal components are still elusive and widely desired.Increasing cost is also a concern of the industry.Microwave processing offers a new method to meet these demands of producing fine microstructures and better properties,and potentially at lower cost.Why does Microwave Sintering Produce better Properties compared to Conventional Processing?There are two main reasons why the microwave process yields better mechanical properties,especially in the case of powder metals-it produces a finer grain size,and the shape of the porosity,if any,is quite different than in a conventional part.In microwave-processed powder metal components,we have observed round-edged porosities producing higher ductility and toughness.Microwave Sintering MechanismsSo far,there has been little effort devoted to understanding the mechanisms and the science behind microwave sintering of metals.However,it is obvious that the microwave-metal interactions are more complex than those working actively in the field had expected.There are many factors that contribute significantly to the total microwave heating of powdered metals.The sample size and shape,the distribution of the microwave energy inside the cavity,and the magnetic field of the electromagnetic radiation are all important in the heating and sintering of powder metals.This research is just at the early stages,and it will be a long time before the exact mechanisms are elucidated.Primary author:Prof.Dinesh AgrawalSource:Materials World,Vol.7no.11pp.672-73November1999.For more information on Materials World please visit The Institute of Materials.Date Added:Oct9,2001Microwave Processing and Engineering CenterMicrowave Processing and Engineering Center106Materials Research Laboratory,The Pennsylvania State UniversityUniversity ParkPennsylvania,16802PH:1(814)865-4548Email:************Visit Microwave Processing and Engineering Center WebsitePrimary ActivityService ProviderCompany BackgroundThis center is the world’s leading institution in the study of the interaction of solid matter with microwave radiation.It has published some150+papers and patents covering a sequence of remarkable discoveries:Increasing the kinetics of all reactions involving the most important materials of modern materials science:BaTiO3;all ferrites,silicon,etc.The practice and principles of Anisothermal reactions in any multiphase systemThe physical separability of the E&H fields at microwave frequenciesThe remarkable differences between the E&H fields in interaction with matter,including...The ability to de-crystallize many of the most significant crystalline phases of material technology in a few seconds without meltingApplication of microwave energy to process metallic materialsMost of the Center support has come from two dozen companies and the Defense Dept,since its science is so “transformative”that the“peers”have yet to catch up with it!!Submission DateSeptember20,2001Sales ContactProf Dinesh AgrawalDirector。

微波介质陶瓷元器件英文

微波介质陶瓷元器件英文When it comes to microwave technology, you can't ignore the crucial role of microwave dielectric ceramic components. These tiny but mighty devices are like the unsung heroes in our advanced communication systems.These ceramic components are specifically designed to handle microwave frequencies with ease. They're made from special materials that have the perfect blend of dielectric properties, ensuring minimal loss of signal as it travels through.One of the coolest things about microwave dielectric ceramics is their ability to withstand extreme conditions. Whether it's high temperatures or harsh environments, these components just keep on ticking, ensuring uninterrupted service.But what really sets them apart is their precision. You see, microwave signals are super sensitive. Even a tiny bitof interference can mess up the whole system. That's why these ceramic components are made to exacting standards, ensuring maximum performance and reliability.And let's not forget about their versatility. Microwave dielectric ceramics can be found in everything fromsatellite communication systems to radar systems and even your smartphone. So, the next time you're enjoying a smooth video call or streaming your favorite show, remember to thank those humble ceramic components for their hard work!。

CST中文教程

CST中文教程CST 中文教程目录第一章—引言 ................................................................. .............................… 3欢迎 ................................................................. ..................................................................3如何快速上手…………............................................................. ........................................ 3CST DESIGN STUDIO是什么...................................................................... ................ 4CST DESIGN STUDIO的主要应用………................................................................ ...... 4CST DESIGN STUDIO 的主要特征.................................................................. ..............5器件…............................................................... .............................................................. 5分析 ................................................................. ................................................................. 5结果管理………................................................................ .................................................. 5显示....... ................................................................ .. (6)资料.......... .............................................................. ......................................................... 6自动化....................................................................... (6)关于此手册...................................................................... . (7)手册中的一些约定…................................................................... ...................................... 7如何反馈….................................................................... ..................................................... 7第二章— QUICK TOUR.................................................................... ...................8用户创界面结构................................................................................ .. (8)建一个系统...................................................................... ..............................................10添加并连接器件…………………... .................................................... ............................... 11改变Block的性质…………... .......................................................... .................................. 16改变外置端口的设置………………….................................................... ........................... 17仿真.................. ..................................................... . (19)单位设置 ..................................................................... . (19)定义仿真目标………… ............................................................. .......................................20开始仿真………................................................................ ............................................... 23查看仿真结果………............................................................ .............................................24标准显示接口……................................................................. ......................................... 24个性化显示接口性质……………............................................................ .......................... 28用户自定义显示接口 ..................................................................... .............................. 30参数化及优化……………….. ....................................................... .....................................31使用参数……. ................................................................ ................................................. 31使用参数扫频……………….. ....................................................... .................................... 36优化…………………….. ................................................... ...............................................41估计额外的结果… ….. .......................................................... .........................................51获取SPICE 网络参数……………………………………………. .................................. ..... 51基于后加工的模版………….. ........................................................... ............................... 53第三章– BLOCK TYPES................................................................... ................55特殊的blocks …………………............................................... ..........................................56参考Block .............................................................. ...............................…….................. 56复制Block .............................................................. ........................................................ 58CST DESIGN STUDIOBlock .................................................................. ........................ 58CST MICROWAVE STUDIOBlocks.............................................................. .................. 62库Block............................................................... ........... .......................................... 69标准Block ...……....................................................... ..................................................... 75电路Blocks.............................................................. ....................................................... 76Sonnet emBlocks.................................................................. ......................................... 81特殊模块属性.......................................................... …………….......................................82修改模块的版图 ..................................................................... ..……………..................... 82模块的内嵌 ..................................................................... ............…………….................. 82为模块选择求解器 ..................................................................... ............……………....... 84使用插值........................................................................... (85)微分端口……………….......................................................... ........................................... 87第四章—仿真任务……................................................................. ....................90S参数仿真………………...................................................... .............................................90AC 仿真…….............................................................. .......................................................91工作点DC 仿真…….........................................…………................. ...............................93天线插件 ..................................................................... .....................................................94谱线仿真……................................................……………....... .........................................95放大器仿真………........................................................... ..............................................100混频器仿真……................................................................. ...........................................102第五章—与 CST MICROWAVE STUDIO 集成…..........................105示例………….......................................................... ........................................................105CST MICROWAVE STUDIO 模型...................................................................... .........106天线 ..................................................................... .. (106)变换器 ..................................................................... ................................................... 108CST DESIGN STUDIO 建模............……................................................. ................108优化…................................................................ .............................................................113天线计算 ..................................................................... ...........................................117第六章–更多信息…………………………….. .................….......................... .....120例子.................................................................. ..............................................................120在线参考文件……………….......................................................... ..................................120获取技术支持......... .......................................................... (120)宏............................................................................. . (1)21改变记录…... ............................................................ ......................................................121附录A — BLOCK REFERENCE .............................................................. ....122基本Blocks …............................................................... ................................................122特殊Blocks ....................................................................................... . (123)传输线 Blockswhite/yellow ……..............…..................……………....... ....................124微带 Blocksred/yellow ... ......................................................... ...........................125矩形波导 Blocksblue/yellow…………..................................................... ...................127其他波导Blocks.............................................................……. ........................................129基本电路Blocks .….............................................................. ........................................130半导体电路Blocks ........................................……..................... ...................................132射频电路Blocks ………………………………………………………....................... ..........134附录 B —快捷键………......................................................................................140可用的快捷键........................................……………….................. .................................140设计时用到的快捷键Canvas.................................…………………................... ........140 第一章—引言欢迎欢迎使用 CST DESIGN STUDIO 这是一个功能强大使用简单的示意图设计工具它是为复杂系统的快速综合及优化设计的。

温度均匀性对微波介质基板介电常数热系数测试的影响

印制电路信息2019No.10检测技术Detection Technology温度均匀性对微波介质基板介电常数热系数测试的影响董彦辉于艺杰（中国电子科技集团公司第四十六研究所，天津300220）张永华（无锡江南计算技术研究所印制板质量检测中心，江苏无锡210023）摘要文章通过采用多点温控和单点温控测试系统，分别对两种微波介质基板的介电常数热系数进行测试的方式，研究分析了温度均匀性对测试介电常数热系数的嚴响。

测试结果表明，对于介电常数热系数介于-0.002%/%2_0.202%/P（-20ppm/%：-20ppm/C）的微波介质基板材料，温度均匀性对于介电常数热系数的测试结果准确性影响较大。

关键词微波介质基板；介电常数热系数；温度均匀性中图分类号：TN41文献标识码：A文章编号：1009-0096（2019）10-0041-05Effect of temperature uniformity on testing dielectric constant thermal coefficient of microwave substrateDong Yanhui YuYijie Zhang YonghuaAbstract The dielectric constant thermal coefficients of samples were measured by multi-point temperaturecontrol and single point temperature-control dielectric constant thermal coefficient test system.The effect of temperature uniformity on dielectric constant thermal coefficient was studied.For microwave dielectric substrate materialswith dielectric constant thermal coefficient between-0.002%/°C〜0.202%/°C(-20ppm/°C and20ppm/°C),the temperatureuniformity has a great influence on the accuracy of the dielectric constant thermal coefficient.Key words Microwave Dielectric Substrate;Dielectric Constant Thermal Coefficient;Temperature Uniformity.0引言目前高频电路基板材料的工作频段已经覆盖了从低频到毫米波范围，而微波、毫米波通信在雷达、遥感、航天测控以及制导等特殊领域的应用，使得基板材料的工作环境覆盖了从零下几十摄氏度到几百摄氏度的范围⑴，介电常数热系数的测试也越来越受到微波介质基板生产企业和使用单位的关注。

英语B词汇分阶记忆2

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一种射频滤波组件自动测试系统的设计与实现

0引言微波部件作为实现重要功能和用途的核心关键部件，广泛应用于仪器、设备、系统等相关领域。

随着科学技术的进步，微波部件等产品的工作频率在不断提高、功能也在不断增加，这就使得微波部件的集成化程度也越来越高。

产品生产制造过程中，需要测试的功能和数据量急剧增加，此外，产品所隐藏的缺陷，特别是稳定性、可靠性，以及环境适应性方面质量的缺陷也随之增多，加剧了制造和测试的难度，传统的手工测试效率低，测试完备性差，亟需通过全面系统的测试，来更有效地发现和解决这些隐藏的缺陷，提高产品的质量品质，满足用户的使用需求。

另外，用户对产品质量、供货周期、价格等要求进一步提高，传统的人工测试越来越无法满足生产制造的迫切需求，因而需要更高效、更可靠、成本更低的测试手段来满足生产制造需要。

研制自动测试系统，实现自动化测试将成为必然的趋势和途径。

射频滤波组件是一种典型的微波多功能组件，测量参数多、数据多，环境适应性等质量测试验证项目多，传统的手动测试不能对产品做全面的可靠、高效的测试，这就需要构建有针对性的自动化测试系统。

1系统方案设计该自动测试系统是由硬件和软件两部分组成。

系统硬件部分主要由工业控制计算机(简称工控计算机)、矢量网络分析仪、NI PCI-6503数字I/O 采集卡、测控装置、电源模块、GPIB 控制卡等装置组成，软件部分以作者简介：尚建波(1984-)，男，助理工程师，主要研究领域为电子测量仪器微波部件测试调试。

一种射频滤波组件自动测试系统的设计与实现T he Design and Implementation of an Automatic Test System of M icrow ave M odule尚建波,展利（中国电子科技集团公司第四十一研究所,山东青岛266555）S hang Jian-bo,Zhan Li (The 41s t I nstitute of China Electronics Technology Group Corporation,Shandong Qingdao 266555）摘要：以TestCenter 软件和矢量网络分析仪为核心，利用GPIB 总线技术，设计搭建了一套微波组件自动测试系统，可实现射频滤波组件多通道增益、带外抑制、相位、压缩点等多参数指标的快速自动测试，并自动记录、存储、处理、汇总和符合性判断测试数据。

Microtrac S3500 微米激光粒度仪使用说明

Largo, FL 33773
9/03
Microtrac S3500 Particle Size Analyzer Operation and Maintenance
iii
Contents
1. INTRODUCTION .................................................................. 1
SYMBOL DEFINITIONS
! This CAUTION symbol on the equipment refers the user to the Product Manual for additional information.
WARNING, risk of electric shock. This symbol warns the user of a potential shock hazard where voltages greater than 30 Vrms, 42.2 Vpeak, or 60 Vdc may be accessible.
Microtrac Inc. 12501-A 62nd Street North
Largo FL 33773 (727) 507-9770
ii
Microtrac S3500 Particle Size Analyzer Operation and Maintenance
9/03
About This Document
CAUTION This product is intended for use in environments defined by IEC Pollution Degree 2, generally what would be expected in an office or laboratory. Industrial environments or those that may result in conductive contamination entering the device, or contamination that may become conductive when combined with condensation, are not suitable for the equipment.

Lab Manual

,Fig.4 shows comparison between measurements of three different samples with empty cavityStep 1: Select the type of cavity either cylindrical cavity or rectangular cavity.Step 2: Browse the ASCII folder on your computer.Step 3: Now select the sample material for which you have to calculate the dielectric constant and the loss factor.Step 4: Run the VI up to see the S21 vs frequency response for the empty cavity and the sample material chosen from the list of sample materials.Step 5: Using the pertur bation technique, the dielectric constant (ε'r), loss factor (ε"r) and the quality factor (Q) of the sample has been calculated.Step 6: In case, you wish to see the dielectric constant (ε'r), loss factor (ε"r) and the quality factor (Q)of other sample materials then click stop and repeat steps 1,2,3 and 4 before running the program again.Task:1. Observe the 3-dB bandwidth for empty cavity and note down the resonant frequency. Repeatthe same steps for cavity filled with Teflon and compare the two results.2. Observe the graph of the empty cavity and the cavity filled with samples, and note down theshift in resonant frequency, loss tangent and dielectric constant of the materials. Use the formulae to calculate the loss factor, dielectric constant and compare with experimental values. Summary: This experiment shows the application of cavity perturbation technique for the estimation of material dielectric constant. This also measures the loss tangent of materials in microwave frequency band. Basically, here we perform comparison of the responses of empty cavity and the cavity filled with sample material.References:1. "Microwave Engineering", Third Edition, David M. Pozer2. "Microwave Devices and Circuits", Third Edition, Edition, Samuel Y.Liao3. "Field and Wave Electromagnetics", Second Edition, David K.Cheng4. "Electromagnetic Waves and Radiating System", Edward C.Jordan, Keith G.Balmain5. Computer Simulation Technology (CST), Darmstadt, Germany, 1998-2003.[online].Available:6. Agilent Application Note - 11949698, "Basics of Measuring The Dielectric Properties ofMaterials"。

Microwave Tuning Elements说明书

M icrowave T uning E lementsR OHS C OMPLIANTT E M E X C E R A M I C S r e s e r v e s t h e r i g h t t o m o d i f y h e r e i n s p e c i f i c a t i o n s a n d i n f o r m a t i o n a t a n y t i m e w h e n n e c e s s a r y t o p r o v i d e o p t i m u m p e r f o r m a n c e a n d c o s t .D ESCRIPTIONEconomical means of introducing a variable reactance to microwave circuits such as waveguides, filters, cavities and other resonant structures High resolution tuningSelf-locking constant torque drive mechanism Excellent tuning stability Low dynamic noiseOne handed adjusting/tuning, no need for locking nut Available with Gold, Silver plating and chromate finish Metallic, dielectric, resistive types availableAdjustments in applications from L to Ka band and beyondHigh Reliability versions are available on special orderCustom design upon requestROHS compliantA PPLICATIONSComb-line and inter-digital filters Coaxial structures Waveguide circuitry Gunn oscillatorsImpedance transformers Space applications020406080100120AT 6922AT 6933AT 6934AT 6935AT 6950AT 6952AT 6924AT 6925AT 6926AT 6927AT 6928AT 6929AT 6948AT 6965AT 6930AT 6995AT 6996AT 6997T e m e x -C e r a m i c s T u n i n g E l e m e n t S e r i e sOperating Frequency GHzM icrowave T uning E lementsR OHS C OMPLIANTI M ICROWAVE T UNING E LEMENTSTuning Elements consist of a brass mounting bushing with a rotor of the same material including atuning rod made of metallic or dielectric or absorbent material and a nut.M icrowave T uning E lementsR OHS C OMPLIANTI.2D IELECTRIC T UNING E LEMENTSDielectric Tuning Elements are used whenever the lowest loss tuning for high frequency applications is required. When dielectric rod is introduced into a cavity, the self resonant frequency is lowered due to the cavity “appearing” larger.The basic dielectrics used in Temex-Ceramics Microwave Tuning Elements are sapphire, quartz and alumina.Part number: AT 6922 ROHS. Bushing and rotor are made of brass gold plated. Usage in the frequency bands X to K. Bushing can be mounted with solder, epoxy or press-fit.M icrowave T uning E lementsR OHS C OMPLIANTT E M E X C E R A M I C S r e s e r v e s t h e r i g h t t o m o d i f y h e r e i n s p e c i f i c a t i o n s a n d i n f o r m a t i o n a t a n y t i m e w h e n n e c e s s a r y t o p r o v i d e o p t i m u m p e r f o r m a n c e a n d c o s t .Recommended rotor tuning tool AT 8762II T UNING R OTORSExtended range metallic and dielectric rotors are used where direct insertion of the tuning element is desired. Taps designed specifically to insure proper fit are available.II.1 M ETALLIC T UNING ROTORSModels made of brass and dimensions in mmP/NThread A B Φ C DSlot W x L AT 6501-3 ROHS M 1.5 x 0.25 4.4 2.3 1.1 0.4 0.25 x 1.1 AT 6501-0 ROHS M 2.5 x 0.25 5.4 3.3 2.1 0.4 x 1.9AT 6501-1 ROHS 4.4 2.3 AT 6501-2 ROHS 7.7 5.6 AT 6995-0 ROHS .094-80 UNS3.1 0.8 1.80.5 0.4 x 1.5AT 6995-1 ROHS 4.2 1.9 AT 6995-2 ROHS 6.1 3.8 AT 6996-1 ROHS .156-64 UNS6.4 3.8 3.2 0.25 0.5 x 3.0AT 6996-2 ROHS 9.7 7.1 AT 6996-3 ROHS 14.0 11.4 AT 6996-4 ROHS 3.2 0.6 AT 6996-5 ROHS 7.5 4.9 AT 6996-6 ROHS 4.6 2.0 AT 6996-8 ROHS 4.9 2.3 AT 6997-0 ROHS .190-64 UNS14.1 11.5 4.1 0.25 0.5 x 3.7AT 6997-1 ROHS 5.3 2.7 AT 6997-2 ROHS 9.1 6.5 AT 6997-3 ROHS 11.4 8.8 AT 6997-4 ROHS 3.3 0.7AT 6997-5 ROHS7.24.6M icrowave T uning E lementsR OHS C OMPLIANTT E M E X C E R A M I C S r e s e r v e s t h e r i g h t t o m o d i f y h e r e i n s p e c i f i c a t i o n s a n d i n f o r m a t i o n a t a n y t i m e w h e n n e c e s s a r y t o p r o v i d e o p t i m u m p e r f o r m a n c e a n d c o s t .II.2 D IELECTRIC T UNING R OTORSP/N Rod material Thread A BΦ C D Slot W x LAT 6930-4 ROHS Sapphire .094-80 UNS5.8 2.50.9 0.5 0.4 x 1.5AT 6930-8 ROHS 6.6 3.5 1.60.5Custom models and dimensions are available upon request.III DRO T UNERSDRO tuners are precision components designed exclusively for tuning dielectric resonator devices such as filters and oscillators. Rod is made of Invar silver plated and disk made of brass silver plated. Different disk diameters are available.Models and dimensions in mmP/NNominal Frequency Disk diameter AT 4010-1 ROHS 2 GHz 24.6 AT 4011-1 ROHS 3 GHz 19.0 AT 4012-1 ROHS 4 GHz12.7AT 4012-2 ROHS15.9M icrowave T uning E lementsR OHS C OMPLIANTT E M E X C E R A M I C S r e s e r v e s t h e r i g h t t o m o d i f y h e r e i n s p e c i f i c a t i o n s a n d i n f o r m a t i o n a t a n y t i m e w h e n n e c e s s a r y t o p r o v i d e o p t i m u m p e r f o r m a n c e a n d c o s t .IV. M ECHANICAL AND G ENERAL S PECIFICATIONSSERIES Bushing Thread Tap P/N Recommended Tap Drill (mm)Rotational Rotor Torque(cm.N) Max Mounting Torque (cm.N)Max Nut Mounting Torque (cm.N)AT 6924 ROHS .120- 80 UNS AT 7060 2.75 0.2 to 2.0 7.0 10.0 AT 6925 ROHS .190-64 UNS AT 7061 4.45 0.3 to 2.8 21.0 30.0 AT 6926 ROHS .234-64 UNS AT 7062 5.50 0.7 to 3.5 35.0 50.0 AT 6927 ROHS .234-64 UNS AT 7062 5.50 0.7 to 3.5 35.0 50.0 AT 6928 ROHS .234-64 UNS AT 7062 5.50 0.7 to 3.5 35.0 50.0 AT 6929 ROHS .190-64 UNS AT 7061 4.45 0.3 to 2.8 21.0 30.0 AT 6933 ROHS .120- 80 UNS AT 7060 2.75 0.2 to 2.0 7.0 10.0 AT 6934 ROHS .234-64 UNS AT 7062 5.50 0.7 to 3.5 35.0 50.0 AT 6935 ROKS .234-64 UNS AT 7062 5.50 0.7 to 3.5 35.0 50.0 AT 6948 ROHS .312-64 UNS AT 7065 7.55 0.7 to 5.0 84.0 70.0 AT 6950 ROHS .120- 80 UNS AT 7060 2.75 0.2 to 2.0 7.0 10.0 AT 6952 ROHS .234-64 UNS AT 7062 5.50 0.7 to 3.5 35.0 50.0 AT 6965 ROHS.469-32 UNSAT 706611.10.7 to 5.6168.0140.0SERIESRotor Thread Tap P/N Recommende d Tap Drill (mm) Recommended Tuning Tool P/NAT 6501-3 ROHS M1.5 x 0.25 AT 7071 1.25AT 8762AT 6501-0, -1, -2ROHSM2.5 x 0.25 AT 7070 2.25 AT 8777AT 6995 ROHS .094-80 UNS AT 7064 2.05 AT 6996 ROHS .156-64 UNS AT 7059 3.55AT 6997 ROHS.190-64 UNSAT 70614.45Precautions to use rotor tunings:Typical drilling diameter is the tap core diameter + 0.1 mmFlange of machined threads has to be perfect, very smooth, without metallic burrs. Use recommended tuning tool.Before screwing the rotor, find the first thread by turning the anti-clockwise.V. P ACKAGINGParts are delivered in bulk.VI. H OW TO ORDERTuning elementsReference ROHSExamplesAT 6924-3 SL ROHSAT 6922 ROHSM icrowave T uning E lementsR OHS C OMPLIANTT E M E X C E R A M I C S r e s e r v e s t h e r i g h t t o m o d i f y h e r e i n s p e c i f i c a t i o n s a n d i n f o r m a t i o n a t a n y t i m e w h e n n e c e s s a r y t o p r o v i d e o p t i m u m p e r f o r m a n c e a n d c o s t .Tuning rotorsReference ROHSExamplesAT 6995-2ROHS AT 6501-3 ROHSDRO tunersReference ROHSExampleAT 4011-1ROHS。

Agilent Scanning Microwave Microscopy 说明书

Scanning Microwave MicroscopeApplication NoteIntroductionMeasuring electromagnetic properties of materials can provide insight into applications in many areas of science and technology, and increasingly, these properties need to be evaluated at the nanometer scale. Since electromagnetic properties, such as the dielectric constant, are ultimately related to a material’s molecular structure, correlating the detailed physical structure of a material with its electromagnetic properties is frequently more valuable than the knowledge of either alone.Agilent Technologies’ Scanning Microwave Microscope (SMM) is a new Scanning Probe Microscope (SPM) that combines the electromagneticmeasurement capabilities of a microwave Vector Network Analyzer (VNA) with the nanometer-resolution and Angstrom-scale positioning capabilities of an Atomic Force Microscope (AFM).Agilent VNAs are mature, highlysophisticated characterization instruments that make extremely accurate, calibrated measurements of complex-valued ratios on electromagnetic signals. The ratios areThe incident signal is generated andcontrolled inside the VNA; as a result, theratios R and T are not merely relative, but referenced to the well-known, accurately quantiﬁed incident signal.This measurement capability, delivered to the apex of an AFM tip makes the SMM the only SPM in its class, enabling calibrated, traceable measurements of electrical properties such as impedance and capacitance, with the high spatial resolution that is the hallmark of a well-designed, well-constructed AFM.Microwave Vector Network AnalyzerThe SMM uses Agilent’s PNA N5230A microwave vector network analyzer(Figure 1).1 Like all network analyzers, this VNA is a stimulus-response instrument, optimized for accurate and repeatablemeasurement of the response of a network or a device under test (DUT) to a known stimulus signal. This is in contradistinction to instruments such as the spectrum analyzer, which are usually conﬁgured as a receiver (only) of an unknown signal, and which do not include a source for a stimulus to be applied to the DUT.A VNA has two operational modes: transmission and reﬂection. In the reﬂection (alternatively, transmission) mode, the VNA measures the magnitude and phase characteristics of the DUTF. Michael Serry1 The main difference between a scalarnetwork analyzer and a VNA is the ability of the VNA to make phase measurements.R =reﬂected signal incident signal, and .T =transmitted signalincident signalFigure 1. PNA (left) andAFM scanner and 5400 (right).Scanning Capacitance Microscopy Measuring the capacitance-to-ground (C) of the tip-sample interface, and its variation (dC/dV) with an applied ACbias (V=V0 Sin[ωt]) is an important extension of atomic force microscopy (AFM) for the electrical characterization of semiconductors. It enables a two-dimensional mapping of the carrier density across different regions of a semiconductor, with applications in the failure analysis, characterization, modelingby comparing the signal that reﬂects off(alternatively, transmits through) thedevice with the stimulus signal.2 Eachmode enables measurement of severaluseful parameters. In the reﬂection mode,the VNA can measure (among otherthings) the impedance of the DUT.3Scanning Impedance Microscopy is amajor application of the SMM.Scanning Impedance MicroscopyOne of the most common applicationsof network analysis is measuring theimpedance of a component, so as toevaluate if it matches the impedanceof the other components with which itmust interface in a network. Impedancemeasurement techniques in networkanalyzers have become quite advancedand reﬁned.The SMM uses the VNA in reﬂectionmode for measuring the impedance of the“network” that includes the tip-sampleinterface.4 In the SMM, the DUT for theVNA consists of the AFM probe and theregion of the sample immediately beneaththe metal-coated AFM tip. One applicationof impedance measurement with SMM isscanning capacitance microscopy (SCM)of semiconductors. Here the AFM tip andthe semiconductor sample form a metal-oxide-semiconductor (MOS) capacitor.(More on SCM later).The incident microwave travels througha series of components before it reachesthe tip-sample interface by means ofa transmission line. The impedancemismatch between the transmissionline and the DUT causes the incidentmicrowave to partially reﬂect from thetip-sample interface back towards thestimulus signal source inside the VNA;this reﬂected signal is proportional tothe impedance mismatch. The incidentmicrowave and the reﬂected microwavetogether contain information about theimpedance of the DUT. See “Sidebar” formore detail.2 In some older model network analyzers, the stimulus signal was taken from a separate source. InAgilent’s PNA N5230A, the knowledge of the stimulus signal is excellent, because it is a (microwave)signal generated inside the VNA with high resolution and stability of both the amplitude andthe frequency.3 Impedance is the total resistance that a DUT presents to the ﬂow of an ac signal at a given frequency.4 The word network as used in “network analyzer” is generic and broadly deﬁned. The origin of its usage(as it now relates to network analysis) goes back to the seminal work of the founders of The HewlettPackard Company, formerly the parent company of Agilent Technologies. Bill Hewlett and David Packardused the term network to refer to the electronic circuits they were using to test their ﬁrst products,which started with signal generators! But as it is used today, the word network can for example applyto a liquid sample or a plastic sample or even a food sample as a DUT in network analysis.5S11 is one of four scattering parameters (S-Parameters), which are used to characterize the responseof a DUT at high frequencies, in a way that is consistent with transmission line theory. All fourS Parameters are ratios of voltage traveling waves entering and exiting the DUT. For more information,please visit Agilent’s website: /networkanalyzers/pnademo.htmFigure 3.and simulation of device performance, and also in the development of the semiconductor fabrication process. Traditionally, a resonant capacitive sensor-based scanning capacitance microscopy (SCM) technique has been used to implement this type of AFM technique with some success. One ofthe main shortcomings of traditional SCM is the difficulty of making absolute measurements of the strength of thetip-ample electrical interaction; therefore, SCM images remain maps of the relative difference in carrier densities acrossthe scanned area. For this reason, accomplishing the much coveted taskof using SCM to reliably and repeatably extract numerical estimates for carrier densities in semiconductor devices remains elusive.Agilent VNA hardware includes precision components for the calibration and performance verification of the instrument, thereby extending its applications tothose that require calibrated, traceable,and absolute measurements of, forexample, capacitance.The SMM makes high-resolution,calibrated measurements of thecapacitance-to-ground between an AFMtip and a semiconductor sample. Thisushers the way for the reliable, repeatableextraction of numerical values of thecarrier densities in a semiconductor. TheSMM typically operates at microwavefrequencies of 1.5-6 GHz, which issubstantially higher than the frequenciesused in traditional SCM (around 900 MHz.)The higher frequencies in SMM lead tobetter sensitivity and (electrical) resolutionfor measuring the tip-sample capacitance.The SMM uses a lock-in amplifier formeasuring the in-quadrature and in-phasecomponents of dC/dV, allowing for thedetermination of the polarity of the majoritycarriers in the semiconductor.Figure 4.Spectroscopy with SMMSMM brings the vast measurementcapabilities of the PNA N5320A to expandAFM-based spectroscopy techniquesfor electromagnetic characterization,beyond anything that has been availablein a commercial product so far.6 Forexample, power sweep and frequencysweep capabilities of the PNA N5320Aare perfectly suited for characterizing thefrequency response of a given location ona sample.Even the PNA N5320A’s most commonmethods for representing measurements,such as the Smith Chart, and the LinearPhase plot, open up a wide range ofpossibilities for spectroscopic techniqueswith AFM. In addition, the PNA N5320Asupports and operates (directly onthe instrument) numerous materialcharacterization software packages fromAgilent; these allow, for example, themeasurement of the complex permittivityof a material.6 Spectroscopic techniques in AFM are conducted by disabling the AFM’s raster scanning, and interrogating the sample at the location of the AFM tip while sweeping a parameter across a range of its values; for example, the amplitude or the frequency of a signal applied to the tip or to the sample. For more information, please visit: /litweb/pdf/5989-8215EN.pdfCalibrated Measurements Agilent’s PNA N5230A measure-ments are calibrated with Agilent’s “ECal,” the electronic calibration kits for fast, simple, accurate calibration of the instrument, including for phase measurements. The instrument’s ﬁrmware makes the calibration a rou-tine push-button task that completes within seconds.Figure 5.AFM Instrumentation from Agilent TechnologiesAgilent Technologies offers high-precision, modular AFM solutions for research, industry, and education. Exceptional worldwide support is provided byexperienced application scientists and technical service personnel. Agilent’s leading-edge R&D laboratories arededicated to the timely introduction and optimization of innovative and easy-to-use AFM technologies./find/afm For more information on Agilent Technologies’ products, applications or services, please contact your local Agilent ofﬁce. The complete list is available at:/find/contactusPhone or FaxUnited States: (tel) 800 829 4444 (fax) 800 829 4433Canada: (tel) 877 894 4414(fax) 800 746 4866China: (tel) 800 810 0189 (fax) 800 820 2816Europe: (tel) 31 20 547 2111Japan: (tel) (81) 426 56 7832 (fax) (81) 426 56 7840Korea: (tel) (080) 769 0800(fax) (080) 769 0900Latin America: (tel) (305) 269 7500Taiwan: (tel) 0800 047 866(fax) 0800 286 331Other Asia Paciﬁc Countries: ***************** (tel) (65) 6375 8100 (fax) (65) 6755 0042Product speciﬁcations and descriptions in this document subject to change without notice.© Agilent Technologies, Inc. 2008Printed in USA, June 16, 20085989-8818ENSummaryThe Scanning Microwave Microscope (SMM) is a new scanning probemicroscope that combines the power of Agilent AFMs with Agilent’s 40-year legacy of excellence to deliver new standards in speed, accuracy, andversatility for microwave network analysis. The applications of SMM include highly-localized measurements of impedance, capacitance, and dielectric properties.The SMM includes robust electro- magnetic environment compatibility elements, as well as built-in precision electronic components. These features allow for calibrated and more sensitive measurements than previously possible with other AFM-based techniques for electrical characterization. The SMM paves the way for extracting from the impedance (capacitance) data reliable numerical estimates of the carrier densities in semiconductors.Mechanical DesignTo take full advantage of theVNA-based measurement scheme, Agilent’s SMM incorporates several innovations into the AFM hardware (Figure 5). These include a sophisticated microwave shielding to improve theinstrument’s electromagnetic compatibility with its surroundings, and minimize the effect of stray capacitances, which are inevitable with the probe’s movement during the raster scanning. The innovation of this design is implemented in such a way as to minimize the impact on the performance of the AFM scanner, where the cantilever holder attaches to the rest of the AFM.。

小升初英语重量比较单选80题

小升初英语重量比较单选80题1. Which is heavier, an apple or a banana? A. The apple. B. The banana. Answer: A. An apple is usually heavier than a banana.2. Which is lighter, a pen or a pencil? A. The pen. B. The pencil. Answer: B. A pencil is generally lighter than a pen.3. Compare the weight of an orange and a strawberry. Which is heavier? A. The orange. B. The strawberry. Answer: A. An orange is heavier than a strawberry.4. Which is heavier, a book or a notebook? A. The book. B. The notebook. Answer: A. A book is typically heavier than a notebook.5. Between a ruler and an eraser, which is lighter? A. The ruler. B. The eraser. Answer: B. An eraser is often lighter than a ruler.6. Which animal is heavier, a dog or a cat?Answer: Usually, a dog is heavier than a cat.7. Is a horse heavier than a donkey?Answer: Yes, a horse is typically heavier than a donkey.8. Which is lighter, a chicken or a duck?Answer: Generally, a chicken is lighter than a duck.9. Is a pig heavier than a sheep?Answer: In most cases, a pig is heavier than a sheep.10. Which animal is the heaviest among a rabbit, a mouse and a hamster?Answer: A rabbit is usually the heaviest among them.11. Which is heavier, a bag of apples or a bag of oranges?A. The bag of apples.B. The bag of oranges.C. They are the same.Answer: A. Apples are usually heavier than oranges.12. Which is lighter, a pillow or a quilt?A. A pillow.B. A quilt.C. They are both light.Answer: A. A pillow is generally lighter than a quilt.13. Which is heavier, a chair or a table?A. A chair.B. A table.C. They have the same weight.Answer: B. A table is usually heavier than a chair.14. Which is lighter, a pen or a book?A. A pen.B. A book.C. They are about the same.Answer: A. A pen is obviously lighter than a book.15. Which is heavier, a lamp or a fan?A. A lamp.B. A fan.C. They are similar in weight.Answer: B. A fan is typically heavier than a lamp.16. The football is heavier than the volleyball. But the basketball is heavier than the football. Which one is the heaviest?A. The footballB. The volleyballC. The basketballD. Can't tellAnswer: C. The basketball is the heaviest because it is heavier than the football, which is heavier than the volleyball.17. The tennis racket is lighter than the badminton racket. The table tennis racket is lighter than the tennis racket. Which one is the lightest?A. The tennis racketB. The badminton racketC. The table tennis racketD. Can't tellAnswer: C. The table tennis racket is the lightest as it is lighter than the tennis racket, which is lighter than the badminton racket.18. The weight of the dumbbell A is 5 kg. The weight of the dumbbellB is 8 kg. Which dumbbell is heavier?A. Dumbbell AB. Dumbbell BC. They are the sameD. Can't tellAnswer: B. Dumbbell B is heavier as it weighs 8 kg while dumbbellA weighs 5 kg.19. The skipping rope A is 200 grams. The skipping rope B is 300grams. Which skipping rope is heavier?A. Skipping rope AB. Skipping rope BC. They are the sameD. Can't tellAnswer: B. Skipping rope B is heavier as it weighs 300 grams and skipping rope A weighs 200 grams.20. The weight of the hula hoop A is 1.5 kg. The weight of the hula hoop B is 1.2 kg. Which hula hoop is lighter?A. Hula hoop AB. Hula hoop BC. They are the sameD. Can't tellAnswer: B. Hula hoop B is lighter as it weighs 1.2 kg and hula hoopA weighs 1.5 kg.21. Which is heavier, a car or a motorcycle?Answer: A car is heavier than a motorcycle. A car is usually larger and has more components, making it heavier.22. Is a bus heavier than a train?Answer: No, a train is usually heavier than a bus. Trains are designed to carry a large number of passengers and heavy cargo.23. Compare the weight of a bicycle and a scooter. Which one is heavier?Answer: A scooter is generally heavier than a bicycle. Scooters have more metal parts and a larger frame.24. Which weighs more, a helicopter or a plane?Answer: A plane is typically heavier than a helicopter. Planes have a larger structure and can carry more fuel and passengers.25. Is a subway train heavier than a tram?Answer: Yes, a subway train is usually heavier than a tram. Subway trains are built for underground travel and have more complex systems and larger capacity.26. Which is heavier, a bag of cement or a pile of bricks?A. The bag of cement.B. The pile of bricks.C. They are the same.Answer: B. Bricks are usually heavier than a bag of cement.27. Compare the weight of a steel beam and a stack of wooden planks. Which is heavier?A. The steel beam.B. The stack of wooden planks.C. It's hard to tell.Answer: A. Steel beams are generally heavier than a stack of wooden planks.28. Which weighs more, a bucket of sand or a sheet of glass?A. The bucket of sand.B. The sheet of glass.C. They have the same weight.Answer: A. Sand is denser and heavier than a sheet of glass.29. Between a block of stone and a roll of insulation material, which is heavier?A. The block of stone.B. The roll of insulation material.C. Cannot be determined.Answer: A. Stones are much heavier than insulation materials.30. Which is heavier, a box of nails or a piece of roofing tile?A. The box of nails.B. The piece of roofing tile.C. It depends.Answer: B. Roofing tiles are typically heavier than a box of nails.31. Which is heavier, a washing machine or a microwave oven?Answer: A washing machine is usually heavier than a microwave oven.A washing machine is a large appliance with many components and a heavy structure, while a microwave oven is relatively smaller and lighter.32. Is a fridge heavier than a TV?Answer: Yes, a fridge is typically heavier than a TV. A fridge needs to hold a large volume of food and has a complex cooling system, making it much heavier.33. Compare the weight of a toaster and an air conditioner. Which one is heavier?Answer: An air conditioner is significantly heavier than a toaster. An air conditioner has a large compressor and other heavy parts, while a toaster is a smaller and lighter appliance.34. Which is lighter, a coffee maker or a freezer?Answer: A coffee maker is usually lighter than a freezer. A freezer is designed to store a large amount of frozen goods and has a substantial body, while a coffee maker is more compact and weighs less.35. Is the weight of a dishwasher greater than that of a fan?Answer: Yes, a dishwasher is usually heavier than a fan. A dishwasher contains various mechanical parts and a water tank, making it heavier compared to a relatively simple fan.36. Which is heavier, the frying pan or the spoon in the kitchen?A. The frying panB. The spoonAnswer: A. The frying pan is usually heavier than the spoon.37. Compare the weight of the plate and the bowl. Which one is heavier?A. The plateB. The bowlAnswer: B. Generally, the bowl is heavier than the plate.38. In the kitchen, which is heavier, the kettle or the mug?A. The kettleB. The mugAnswer: A. The kettle is typically heavier than the mug.39. Which weighs more, the pot or the ladle?A. The potB. The ladleAnswer: A. The pot is usually heavier than the ladle.40. Between the oven glove and the tea towel, which is heavier?A. The oven gloveB. The tea towelAnswer: A. The oven glove is often heavier than the tea towel.41. Which is heavier, a pen or a pencil?A. A penB. A pencilC. They are the sameD. It's hard to say.Answer: A. A pen is usually heavier than a pencil.42. Compare the weight of a notebook and a workbook. Which one is heavier?A. A notebookB. A workbookC. Both are the sameD. Can't tell.Answer: B. A workbook is often heavier than a notebook.43. Which is heavier between an eraser and a ruler?A. An eraserB. A rulerC. They have the same weightD. Not sure.Answer: B. A ruler is typically heavier than an eraser.44. Is a stapler heavier than a marker?A. YesB. NoC. MaybeD. Impossible to know.Answer: A. A stapler is heavier than a marker.45. Compare the weight of a glue stick and a pair of scissors. Which is heavier?A. A glue stickB. A pair of scissorsC. They weigh the sameD. It's not clear.Answer: B. A pair of scissors is usually heavier than a glue stick.46. Which toy is heavier, the teddy bear or the doll? A. The teddy bear.B. The doll.C. They are the same. Answer: A. The teddy bear is usually heavier than the doll.47. The toy car weighs 500 grams and the toy plane weighs 800 grams. Which is heavier? A. The toy car. B. The toy plane. C. They are both heavy. Answer: B. The toy plane weighs 800 grams, which is more than the 500 grams of the toy car.48. Compare the weights of the toy train and the toy boat. The toy train is 1 kilogram and the toy boat is 700 grams. Which is heavier? A. The toy train. B. The toy boat. C. They are equal. Answer: A. 1 kilogram is more than 700 grams, so the toy train is heavier.49. The weight of the toy robot is 1.5 kilograms and the weight of the toy helicopter is 1.2 kilograms. Which is heavier? A. The toy robot. B. The toy helicopter. C. They are the same. Answer: A. 1.5 kilograms is greater than 1.2 kilograms, so the toy robot is heavier.50. Among the toy dinosaur, the toy elephant and the toy monkey, the toy dinosaur weighs 2 kilograms, the toy elephant weighs 3 kilograms and the toy monkey weighs 1.8 kilograms. Which is the heaviest? A. The toy dinosaur. B. The toy elephant. C. The toy monkey. Answer: B. The toy elephant weighs 3 kilograms, which is more than the weights of the toy dinosaur and the toy monkey.51. Which dress is heavier, the blue one or the red one?Analysis: You need to compare the weights of the two dresses based on the given colors. The answer depends on the specific descriptions or information provided about the dresses.52. The coat is heavier than the sweater. True or False?Analysis: You have to decide if the statement is correct based on your knowledge of the weights of coats and sweaters. Usually, a coat is heavier than a sweater.53. Which is lighter, the cotton shirt or the silk shirt?Analysis: Consider the material of the shirts. Silk is generally lighter than cotton.54. The leather jacket is as heavy as the denim jacket. True or False?Analysis: Think about the materials of leather and denim to determine if they are likely to have the same weight. Usually, they have different weights.55. Is the wool scarf heavier than the cotton scarf?Analysis: Know the properties of wool and cotton to answer this question. Wool is often denser and heavier than cotton.56. Which is heavier, a sofa or a chair?A. The sofaB. The chairAnswer: A. A sofa is usually heavier than a chair.57. Compare the weight of a bed and a table. Which one is heavier?A. The bedB. The tableAnswer: A. A bed is generally heavier than a table.58. Which is heavier between a wardrobe and a stool?A. The wardrobeB. The stoolAnswer: A. A wardrobe is typically heavier than a stool.59. Is a dresser heavier than a bench?A. YesB. NoAnswer: A. A dresser is often heavier than a bench.60. Which weighs more, a bookshelf or a nightstand?A. The bookshelfB. The nightstandAnswer: A. A bookshelf usually weighs more than a nightstand.61. Which is heavier, a box of apples or a bag of oranges?Answer: Usually, a box of apples is heavier. Because a box can hold more apples than a bag can hold oranges.62. A cake weighs 500 grams and a loaf of bread weighs 800 grams. Which is heavier?Answer: The loaf of bread is heavier. 800 grams is more than 500 grams.63. Compare the weight of a watermelon and a bunch of grapes. Which one is usually heavier?Answer: A watermelon is usually heavier. Watermelons are much larger and heavier than a bunch of grapes.64. A packet of biscuits weighs 250 grams and a chocolate bar weighs 100 grams. Which is heavier?Answer: The packet of biscuits is heavier. 250 grams is greater than 100 grams.65. A bucket of ice cream weighs 1500 grams and a tub of yogurt weighs 800 grams. Which is heavier?Answer: The bucket of ice cream is heavier. 1500 grams is much more than 800 grams.66. Which book is heavier, the storybook or the comic book?Answer: It depends on the number of pages and the material of the books. Usually, if the storybook has more pages or is made of thicker paper,it might be heavier. But if the comic book has more illustrations and thicker pages, it could be the heavier one.67. The dictionary is heavier than the textbook. True or False?Answer: It depends on the specific dictionary and textbook. Some dictionaries are very thick and heavy, while some textbooks might also be large and heavy. So, we can't say for sure without knowing the details. The answer is Maybe.68. Compare the weight of the English book and the math book. Which one is likely to be heavier?Answer: Generally, the math book might be heavier if it has more exercises and graphs. But if the English book has a lot of supplementary materials, it could also be heavy. So, it's hard to tell exactly. The answer is It varies.69. The history book is much heavier than the science book. Why?Answer: This might be because the history book often contains more text and illustrations to cover a wide range of events and periods. However, it also depends on the specific editions and contents of the books. The answer is Due to more content.70. Which is heavier between the geography book and the art book?Answer: It depends on the size, number of pages, and the quality of paper used. Sometimes the geography book might have more maps and thicker pages, making it heavier. But the art book could also be heavy if ithas many color prints. The answer is Uncertain.71. Which instrument is heavier, the guitar or the violin?Answer: Usually, the guitar is heavier than the violin.72. Is the piano heavier than the flute?Answer: Yes, the piano is much heavier than the flute.73. Compare the weight of the drum and the saxophone.Answer: The drum is typically heavier than the saxophone.74. Which is lighter, the trumpet or the harp?Answer: The trumpet is lighter than the harp.75. Is the clarinet as heavy as the tuba?Answer: No, the tuba is heavier than the clarinet.76. Which is heavier, a piece of wood for handcraft or a ball of wool?A. The piece of woodB. The ball of woolC. They are the same weightD. It's hard to say.Answer: A. The piece of wood is usually heavier than a ball of wool.77. Compare the weight of a box of beads and a roll of ribbon for handcraft. Which is heavier?A. The box of beadsB. The roll of ribbonC. They have the same weightD. It depends.Answer: A. Generally, a box of beads is heavier than a roll of ribbon.78. Which is heavier between a bag of clay and a set of scissors for handcraft?A. The bag of clayB. The set of scissorsC. They weigh the sameD. Can't tell.Answer: A. A bag of clay is much heavier than a set of scissors.79. When comparing the weight of a tube of glue and a stack of paper for handcraft, which is heavier?A. The tube of glueB. The stack of paperC. They are equally heavyD. Not sure.Answer: B. A stack of paper is typically heavier than a tube of glue.80. Which weighs more, a can of paint or a pair of scissors for handcraft?A. The can of paintB. The pair of scissorsC. They have the same weightD. Impossible to say.Answer: A. A can of paint is definitely heavier than a pair of scissors.。

Agilent 材料测量解决方案中的电润性材料测量说明书

A wide variety of industries need a better understanding of the materials they are working with to shorten design cycles, process monitoring, and quality assurance. Every material has a unique set of electrical characteristics that are dependent on its dielectric properties. Accurate measurements of these properties can provide scientists and engineers with valuable information to properly incorporate the material into its intended application. A dielectric materials measurement can providecritical design parameter informationfor many electronics applications. For example, the loss of a cable insulator, the impedance of a substrate, or the frequency of a dielectric resonator can be related to its dielectric properties. More recent applications in the area of aerospace, automotive, food and medical industries have also been found to benefit from knowledge of dielectric properties. The material evaluation systemsthat generate these measurements must combine precise measurement instruments, test fixtures that hold the material under test (MUT), and software that calculate and display material parameters. Agilent offers you fast, accurate and often non-destructive solutions.The measurement instruments, such as network analyzers, impedance analyzers and LCR meters provide accurate measurement results with wide frequency range up to 1.1 THz. Fixtures are available that are based on coaxial probe, parallelplate, coaxial/waveguide transmissionlines, free space and resonant cavitymethods. The easy-to-use materialsmeasurement software streamlines theprocess of measuring complex permittivityand permeability. The table below showsproduct examples that can be measuredby Agilent’s material test solutions.• Fast, accurate and non-destructive solutions• Wide frequency coverage,up to 1.1 THz• A variety of measurementmethods supportedIndustry Application/productsElectronics Capacitor, substrates, PCB, PCB antenna, ferrites, absorbers, SARphantom materialsAerospace/defense Stealth, RAM (radiation absorbing materials), radomesIndustrial materials Ceramics & composites: A/D and automotive components, coatingsPolymers & plastics: ﬁ bers, ﬁ lms, insulation materialsHydrogel: disposable diaper, soft contact lensLiquid crystal: displaysOther products containing these materials: tires, paint, adhesives, etc. Food & agriculture Food preservation (spoilage) research, food development for microwave,packaging, moisture measurementsForestry & mining Moisture measurements in wood or paper, oil content analysis Pharmaceutical &medicalDrug research and manufacturing, bio-implants, human tissuecharacterization, biomass, fermentation 19812There are several measurement techniques that exist for measuring dielectric properties of materials. Users need to verify which technique is appropriate for their MUT. Agilent solutions cover all the measurement techniques.Coaxial probe methodThe coaxial probe method is best for liquids and semi-solid (powder) materials. The method is simple, convenient, non-destructive and with one measurement. A typical measurement system consists of a network analyzer or impedance analyzer, a coaxial probe and software. Both the software and the probe are included in the Agilent 85070E dielectric probe kit. Depending on the analyzer and probe used, we can measure from 10 MHz to 50 GHz.The high temperature probe (a) withstands a wide –40 to +200°C temperature range. The large flange allows measurements of flat surfaced solid materials, in addition to liquids and semi-solids. The slim probe (b) allows it to fit easily in fermentation tanks, chemical reaction chambers, or other equipment with small apertures. The performance probe (c) combines rugged, high temperature and frequency performance in a slim design. The probe can be autoclaved, so it is perfect for applications in the food, medical, and chemical industries where sterilization is a must.Transmission line methodThe transmission line method is a broadband technique for machine-able solids. It puts the MUT inside a portion of an enclosed transmission line.Free space methodFree space methods use antennas to focus microwave energy at or through a slab of material. This method is non-contacting and can be applied under high temperatures. It is especially useful at mm-wave frequencies.Resonant cavity methodResonant cavities are high Q structures that resonate at certain frequencies. A sample of the material affects the center frequency and Q factor of the cavity. The permittivity can be calculated from these parameters. Agilent offers 85072A 10 GHz split cylinder resonator, as well as Split post dielectric resonators (SPDR).Parallel plate capacitor method The parallel plate capacitor method involves sandwiching a thin sheet of material between two electrodes to form a capacitor. The method works best foraccurate, low frequency measurements of thin sheets or liquids. A typicalmeasurement system using the parallel plate method consists of an LCR meter or impedance analyzer. Agilent offers several test fixtures such as 16451B, 16452A and 16543A depending on material types and applied frequency ranges that can cover up to 1 GHz.Inductance measurement methodThis method derives the permeability by measuring the inductance of the material (toroidal core). The concept is to wind some wire around MUT and evaluate the inductance with respect to the ends of the wire. The Agilent 16454A magnetic material test fixture provides an ideal structure for single-turn inductor, with no flux leakage when a toroidal core is inserted in it.Agilent 85070E dielectric probe kitFigure 1. Materials measurement techniques3E4991A impedance/material analyzer,1 MHz to 3 GHzFigure 2. Agilent materials measurement ﬁ xturesAgilent offers a variety of fixtures and measurement instruments that covers many material types. The software is also provided depending on required measurement techniques or instruments. See related literature for more information.Test fixtures and instrumentsThe lineup of Agilent test fixtures is summarized in Figure 2. See Table 1 for available measurement instruments.SoftwareThe Agilent 85071E materials measurement software streamlines the process of measuring complex permittivity and permeability with a network analyzer. The easy-to-use software guides the user through setup and measurement, instantly converting S-parameter network analyzer data into the data format of your choice and displaying the results within seconds. Results can be charted in a variety of formats: e r’,e r”, tan δ, μr’, μr”, tan δm and Cole-Cole.A variety of measurement methods and mathematical models are provided to meet most application needs. The free space calibration option provides Agilent’s exclusive gated reflect line (GRL) calibration for measuring materials in free space. Arch reflectivityoption automates popular NRL arch method for measuring reflections off the surface of a sample. Resonant cavity option offers the highest loss tangent accuracy and resolution.Agilent network analyzers, up to 1.1 THz4294A precision impedance analyzer,40 Hz to 110 MHzPNA family network analyzersENA series network analyzers/qualityAgilent Channel Partners/find/channelpartners Get the best of both worlds: Agilent’s measurement expertise and product breadth, combined with channel partner convenience./find/myagilent A personalized view into the information most relevant to you.myAgilent/find/AdvantageServices Accurate measurements throughout the life of your instruments.Agilent Advantage ServicesThree-Year Warranty/find/ThreeYearWarranty Agilent’s combination of product reliability and three-year warranty coverage is another way we help you achieve your business goals: increased confidence in uptime, reduced cost of ownership and greater convenience.For more information on AgilentTechnologies’ products, applications or services, please contact your local Agilent office. The complete list is available at:/find/contactus Americas Canada (877) 894 4414 Brazil (11) 4197 3600Mexico 01800 5064 800 United States (800) 829 4444Asia Paciﬁ c Australia 1 800 629 485China 800 810 0189Hong Kong 800 938 693India 1 800 112 929Japan 0120 (421) 345Korea 080 769 0800Malaysia 1 800 888 848Singapore 180****8100Taiwan 0800 047 866Other AP Countries (65) 375 8100Europe & Middle East Belgium 32 (0) 2 404 93 40 Denmark 45 45 80 12 15Finland 358 (0) 10 855 2100France 0825 010 700**0.125 €/minuteGermany49 (0) 7031 464 6333 Ireland 1890 924 204Israel 972-3-9288-504/544Italy 39 02 92 60 8484Netherlands 31 (0) 20 547 2111Spain 34 (91) 631 3300Sweden 0200-88 22 55United Kingdom 44 (0) 118 927 6201For other unlisted countries: /find/contactus(BP-3-1-13)Product specifications and descriptions in this document subject to change without notice.© Agilent Technologies, Inc. 2013Published in USA, April 5, 20135991-2171ENRelated LiteratureBasics of Measuring the DielectricProperties of Materials, Application note, Literature number 5989-2589EN Solutions for Measuring Permittivity and Permeability with LCR Meters and Impedance Analyzers, Application note, Literature number 5980-2862EN Split Post Dielectric Resonators for Dielectric Measurements of Substrates, Application note, Literature number 5989-5384ENAgilent 85070E Dielectric Probe Kit, Technical overview, Literature number 5989-0222ENAgilent 85071E Materials Measurement Software, Technical overview, Literature number 5988-9472ENAgilent 85072A 10-GHz Split Cylinder Resonator, Technical overview, Literature number 5989-6182ENAgilent LCR Meters, Impedance Analyzers and Test Fixtures, Selection guide, Literature number 5952-1430EWeb ResourcesVisit our websites for additional product information.Materials Test Equipment:/find/materials Network Analyzers:/find/naImpedance Analyzers and LCR Meters: /find/impedance。

Microwave ,materials joining

ABSTRACT: This paper discusses pioneering work and developments in the area of microwave applications into materials welding and joining. In particular, the various microwave techniques for welding metals using microwave induced plasma jet, and joining polymers and ceramics utilising electromagnetic field focussing facilities are detailed. The employment of microwaves for fast curing adhesives for joining transparent to microwave radiation materials is also explained. Both autogenous and heterogeneous materials welding and joining applications are outlined together with the mechanisms and heat transfer phenomena taking place during the bonding process. While relatively low dielectric loss materials are joined using bonding agents susceptible to microwave radiation for wetting the surfaces to be fused, high dielectric loss materials are diffusion bonded resulting in high bond to parent material strength ratio. In the latter case, generated heat is dissipated into the fusion zone volumetrically and the joining process does not rely on conduction heating from the surface, as in the former case. Future research directions for further developments are also discussed in the paper and concluding remarks point to the encouragement of more efforts in this new field of materials processing using microwaves.

深亚微米纳米半导体器件模型

该模型适于沟长大于2微米,沟道宽度在6微米左右，栅氧化层厚度大于250埃的MOSFET。考虑的主要的二级效应包括：
（1）短沟和窄沟效应对阈值电压的影响。（2）表面电场对载流子迁移率的影响。（3）载流子的漂移度饱和。（4）亚阈值电流（弱反型电流）。计算速度慢，精度仍不够，输出电阻不连续
Institute of Microelectronics PKU
MOSFET的三级模型
MOSFET的三级模型是一个包括短沟和窄沟等二级效应的半经
经验验模模型型。参与M数O与S器FE件T尺的寸二有级关模。型该相模比型，适计于算沟效长率大较于高1，μ但m它,栅的氧
化层大于200埃的MOSFET。其中主要考虑的二级效应有：（1）漏压感应的表面势垒降低（DIBL）对阈值电压的影响。（2）短沟和窄沟效应对阈值电压的影响。（3）表面电场对载流子迁移率的影响。（4）载流子的漂移速度饱和。三级模型中的亚阈值区电流与二级模型相同。计算速度快，但输出电阻不连续
在BSIM模型许多模型参数，与沟道的长度和宽度有关，
参数对 L（e 有效沟长）和 W（e 有效沟宽）的敏感程度由
参数名前加字母“L”和“W”表示。如 VFB 是以单位为伏特
的基本参数，而LVFB和WVFB是参数VFB与沟道长度和宽度的敏感程度即敏感因子，它们的单位为 V ⋅ μm.
一般与沟道长度和宽度有关的参数可表示为：
DIGITAL VS. ANALOG
• 数字电路模型的不足
– 电流曲线拟和很好时，输出电导相差很大
Institute of Microelectronics PKU
DIGITAL VS. ANALOG

安全门禁英文翻译

第一篇翻译门禁管理系统原理门禁系统是最近几年才在国内广泛应用的又一高科技安全设施之一，现已成为现代建筑的智能化标志之一。

门禁，即出入口控制系统，是对出入口通道进行管制的系统，门禁系统是在传统的门锁基础上发展而来的（英文 ENTRANCE GUARD /ACCESS CONTROL）。

在现实中访问控制是，我们的日常生活中的现象。

一车门上的锁，本质上是一种形式的访问控制。

在一家银行的 ATM 系统是一个PIN 访问控制的另一种方式。

站在一家夜总会门前的安保人员是缺乏涉及信息技术，也许是更原始的访问控制模式。

拥有访问控制是当人寻求安全，机密或敏感的信息和设施时非常重要的 .项目控制或电子钥匙管理的区域内（和有可能集成）。

一个访问控制系统，它涉及到管理小资产或物理（机械）键的位置。

一个人可以被允许物理访问，根据支付，授权等。

有可能是单向交通的人，这些都可以执行人员，如边防卫兵，一个看门人，检票机等，或与设备，如旋转门。

有可能会有围栏，以避免规避此访问控制。

在严格意义上的访问控制（实际控制访问本身）的另一种方法是一个系统的检查授权的存在，例如，车票控制器（运输）。

一个变种是出口控制，例如的店（结帐）或一个国家。

在物理安全方面上的访问控制是指属性，建筑，或授权人一个房间，限制入口的做法。

在这些环境中，物理密钥管理还可以进一步管理和监控机械键区或某些小资产。

物理访问控制访问的一种手段，是谁，地点和时间的问题。

访问控制系统决定谁可以进入或退出，在那里他们被允许离开或进入，而当他们被允许进入或退出。

从历史上看，这已经部分实现通过钥匙和锁。

当门被锁定只有有人用一把钥匙可以通过门禁，这时取决于锁定如何配置。

机械锁和钥匙的钥匙持有人在特定的时间或日期内允许访问。

机械锁和钥匙不提供任何特定的门上使用的密钥记录，可以很容易地复制或转移到未经授权的人。

当机械钥匙丢失或钥匙持有人不再授权使用受保护的区域，锁必须重新键入。

电子访问控制使用计算机来解决机械锁和钥匙的限制广泛的凭证可以用来取代传统的机械按键。

微波吸收剂吸波性能对比分析

微波吸收剂吸波性能对比分析吕绪良;吴超;曾朝阳;谢卫;王榕【摘要】To compare the absorbing properties of different microwave absorbent and their mixture, firstly using Maxwell-Garnett (MG) formula the effective electromagnetic parameter was calculated of the mixture of X band resistance-type carbon fiber absorbent and magnetic dielectric type ferrite absorbent in different proportion, and their absorbing properties analyzed. Then the resistance matching character and attenuation coefficient of the materials were compared, which proves that adding carbon fiber in ferrite cannot improve absorption properties. Although the ability of attenuation would be enhanced when the resistance materials and magnetic materials are mixed with each other, doping will destroy the materials' resistance matching character because the resistance materials have high permittivity. It makes reflection increase and cannot improve absorbing properties.%为了对比不同类型微波吸收剂及其混合物的吸波性能,利用MG公式,计算了X波段电阻型碳纤维吸收剂和磁介质型铁氧体吸收剂在不同配比下的混合物的等效电磁参数,并分别分析了其吸波性能.通过对比材料的阻抗匹配特性和衰减系数表明,在铁氧体中添加碳纤维并不能提高吸波性能.虽然混合吸收剂兼具电损耗和磁损耗,可以增强对电磁波的衰减,但是由于一般的电性材料具有较高的介电常数,掺杂磁性材料会破坏材料的阻抗匹配特性,使得表面反射增强,吸波性能得不到改善.【期刊名称】《解放军理工大学学报（自然科学版）》【年(卷),期】2012(013)006【总页数】4页(P669-672)【关键词】吸波材料;微波吸收剂;等效电磁参数【作者】吕绪良;吴超;曾朝阳;谢卫;王榕【作者单位】解放军理工大学野战工程学院,江苏南京210007;解放军理工大学野战工程学院,江苏南京210007;解放军理工大学野战工程学院,江苏南京210007;解放军第63983部队,江苏无锡214035;解放军第61135部队,北京102211【正文语种】中文【中图分类】E951.4吸波材料是隐身材料中发展最快应用最广的材料。