射频工程师面试题_40题

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(完整版)射频试题(判断选择计算-含答案)

判断题：1、无耗传输线终端短路，当它的长度大于四分之一波长时，输入端的输入阻抗为容抗，将等效为一个电容。

2、无耗传输线上驻波比等于1时，则反射系数的模等于0。

3、阻抗圆图上，|Γ|=1的圆称为单位圆，在单位圆上，阻抗为纯电抗，驻波比等于无限大。

4、只要无耗传输终端接上一个任意的纯电阻，则入射波全部被吸收，没有反射，传输线工作在匹配状态。

5、在传输线上存在入射波和反射波，入射波和反射波合成驻波，驻波的最大点电压值与最小点上的电压值的比即为传输线上的驻波比。

6、导纳圆图由等反射系数圆、等电抗圆和等电阻圆组成，在一个等电抗圆上各点电抗值相同。

7、圆波导的截止波长与波导的截面半径及模式有关，对于TE11模，半径越大，截止波长越短。

8、矩形波导的工作模式是TE10模，当矩形波导传输TE10模时，波导波长（相波长）与波导截面尺寸有关，矩形波导截面的窄边尺寸越小，波导波长（相波长）越长。

9、在矩形谐振腔中，TE101模的谐振频率最小。

10、同轴线是TEM传输线，只能传输TEM波，不能传输TE或TM波。

11、矩形波导传输的TE10波，磁场垂直于宽边，而且在宽边的中间上磁场强度最大。

12、圆波导可能存在“模式简并”和“极化简并”两种简并现象。

13、矩形波导中所有的模式的波阻抗都等于377欧姆。

14、矩形谐振腔谐振频率和腔体的尺寸与振荡模式有关，一般来讲，给定一种振荡模式，腔体的尺寸越大，谐振频率就越高。

15、两段用导体封闭的同轴型谐振腔，当它谐振在TEM模时，其长度等于半波长的整数倍。

16、对称振子天线上的电流可近似看成是正弦分布，在天线的输入端电流最大。

17、对称振子天线既可以作发射天线，也可以作接收天线，当它作为发射天线时，它的工作带宽要比作为接收天线时大。

18、天线阵的方向性图相乘原理指出，对于由相同的天线单元组成的天线阵，天线阵的方向性图可由单元天线的方向性图与阵因子相乘得到。

19、螺旋天线的工作模式有法向模、轴向模和边射模三种，其中轴向模辐射垂直极化波。

射频工程师面试题目

电气专业试题（共100分）1. 请简述变压器并列运行的条件有哪些？（5分）1、相同额定电压2、Ud％相差不大于10%3、组别相同2. 变压器在安装前需检查哪些内容？（5分）1、变压器有无漏油现象2、变压器瓷瓶有无破损裂纹现象3、变压器的特性试验，包含（直阻，绝缘，耐压，变比，容量）4、除去灰尘3. 普通微机线路保护中的三段保护指的是什么？（5分）电流速断、限时电流速断过电流保护4. 并联电容器在电力系统中的作用是什么？（5分）1、补偿感性电流2、提高电网电压3、抑制谐波5. 导电膏有哪些作用?主要应用于哪些方面?使用导电膏有那些注意事项？（5分）导电膏可以保护导体的接触面不被氧化，主要应用于铜排搭接面处、隔离开关咬合处。

导电膏涂抹要均匀，不能涂抹太厚，注意美观。

6. 一台500kV A的10kV欧变，如果选用津低的框架式开关作为主进开关，参数和型号应该如何选择？（5分）A TW30-1000 抽屉式开关3P，操作电源AC220V，标准控制模块。

7. 开关柜仪表门上的分合闸按钮和指示灯按什么顺序排列？分别是什么颜色？（5分）指示灯黄红绿储能、合位、分位按钮绿红合闸、分闸8. 开关柜中的五防包括那些内容？（5分）1. 防带负荷拉合隔离开关；2. 防误拉合断路器；3. 防带电挂地线；4. 防带地线合闸；5. 防误入带电间隔。

9. 请画出两按钮方式的交流接触器控制回路原理图。

（5分）10. 欧式电缆分支箱和美式电缆分支箱有什么区别?（5分）1、额定电流的区别：欧式电缆分支箱为630A，美式电缆分支箱为600A。

2、电缆头的区别：欧式电缆分支箱采用欧式电缆头，欧式电缆头分可触摸和不可触摸两种，美式电缆分支箱采用美式电缆头，只有可触摸。

3、安装方式：欧式电缆分支箱采用的母排为穿墙套管形式，美式电缆分支箱采用的母排为异形母排。

11. 两台主变的35kV变电站，如果采用安通尼的保护装置，主变保护应该如何进行配置？需要几台保护装置？（5分）设置高后备、变压器差动、开关量信号的测量控制投切的测控装置，也有加低后备ASB225B高后备AST211差动ASR-221测控，如果需要可以增加一台低后备ASB225B12. 10kV和35kV的安全距离是多少（分别叙述相间、相对地、断口）？（5分）电压等级相间相对地断口10kV 125mm 125mm 125 mm35 kV 300 mm 300 mm 300 mm13. 请简述10kV和35kV开关柜主回路和变压器工频耐压值（分别叙述相间、相对地、断口）？（5分）电压等级主回路相间主回路相对地主回路断口变压器10kV 42 kV 42 kV 48 kV 35kV35 kV 95kV 95 kV 118 kV 65kV14. 请简述断路器、负荷开关、隔离开关的区别是什么？（5分）断路器用在分开短路电流和操作较频繁的地方，价格高负荷开关只能分开额定电流，用在不频繁操作且可以正常分断电流的地方，于熔断器配合，用在保护变压器等的地方隔离开关只做为分开线路作用，给人操作时一个明显的断开点15. 变电站的“五遥”分别是什么？（5分）遥控，遥测、遥信、遥调、遥视16. 电力系统接地方式有哪些？（5分）低压一般直接接地、10kV一般不接地、35kV不接地或经高阻接地，以及经过消弧线圈接地（或接地变）17. 请简述电流互感器精度等级的含义，0.2S/0.5/10P10? （5分）0.2S指0.2%精度且可以满足一定的磁通过饱余量0.5指精度为0.5％10P10精度为10％过载倍数为10倍18. 我公司普通欧式箱变的防护等级是多少?含义是什么？（5分）IP3319. 使用电流互感器接线应该注意什么？（5分）电流互感器接线应不能开路，防止产生高电压20. 请简述35kV常规变电站应该配置的保护种类？（5分）1、变电站应设置变压器保护差动、高后备、低后备、变压器的测量和控制调压2、35kV进线设置线路保护或进线备投装置3、10kV或35kV有分段设分段备投装置4、10kV设线路保护5、10kV电容保护6、35kV或10kV设站用变保护机械专业试题（100分）21. XGN-12型电缆进线柜（带上下隔离和上接地开关），简述停电操作顺序？（5分）分闸顺序：按钮或开关分断路器，操作盘下隔离、上隔离、上接地、下接地，操作完成后闭锁下门的打开，开下门，直拨锁打开后开后门，（也可后门封死）22. 设计冷冲压零件，你综合考虑过钢板的材料利用率吗？应该达到多少？（2分）23. 请用制图符号标注出45号钢的一般淬火要求（洛氏硬度）。

射频工程师测试题

射频工程师测试题射频工程师测试题RF Quiz #11. What is the impedance of free space?377ou2. What happens to the noise figure of a receiver when a 10 dB attenuator is added at theinput?a) Noise figure increases by 10 dBb) Noise figure decreases by 10 dBc) Noise figure doesn't change3. An RF system has a linear throughput gain of +10 dB and an output 3rd-order intercept point(OIP3) of +30 dBm. What is the input 3rd-order intercept point(IIP3)? a) +20 dBmb) +40 dBmc) +30 dBm4. Which filter type has the greatest selectivity for a given order(i.e., N=5)? a) Besselb) Chebychev (ripple=0.1 dB)c) Butterworth5. Which mixer spurious product is a 5th-order product?a) 1*LO + 5*RFb) 6*LO - 1*RFc) 3*LO - 2*IF6. A 2.8 GHz oscillator is phase-locked to a 10 MHz reference oscillator that has a single-sidedphase noise of -100 dBc at 1 kHz offset. What is the single-sided phase noise of the 2.8 GHzoscillator at 1 kHz offset?a) -48.6 dBcb) -100 dBcc) -51.1 dBc7. What is the power of a 2 Vpk-pk sine wave across a 50 ohm load? a) -20.0 dBmb) +10.0 dBmc) +19.0 dBm8. Which 2-port S-parameter is commonly referred to as "reverse isolation" in an amplifier? a) S21b) S22c) S129. What are the minimum and maximum combined VSWR limits at an interface characterized bya 1.25:1 VSWR and a 2.00:1 VSWR?a) 1.75:1 (min), 2.25:1 (max)b) 1.60:1 (min), 2.50:1 (max)c) 0.75:1 (min), 3.25:1 (max)10. An ideal directional coupler has a directivity of 25 dB and an isolation of 40 dB. What is itscoupling value? I=D+Ca) 65 dBb) 40 dBc) 15 dBRF Quiz #2 1. On a Smith chart, what does a point in the bottom half of the chart represent? a) An inductive impedanceb) A capacitive impedancec) Power saturation2. While we're on the subject of Smith charts, what is the impedance of the point at the far leftedge of the center horizontal line?a) Infinite ohms (open circuit)b) Zero ohms (short circuit)c) 50 ohm match3. A single-conversion downconverter uses a high-side localoscillator (LO) to translate the inputradio frequency (RF) to an intermediate frequency (IF). Will spectral inversion occur at IF? a) Yes, alwaysb) No, neverc) Sometimes4. What happens to the noise floor of a spectrum analyzer when the input filter resolutionbandwidth is decreased by two decades?a) 20 dB increaseb) 20 dB decreasec) 40 dB decrease5. What is a primary advantage of a quadrature modulator?a) Low LO power requiredb) Four separate outputsc) Single-sideband output6. What is meant by dBi as applied to antennas?a) Isolation in decibelsb) Physical size relative to intrinsic antennasc) Gain relative to an isotropic radiator7. What is the power dynamic range of an ideal 12-bit analog-to-digital converter (ADC)? a) 36.12 dBb) 120 dBc) 72.25 dB8. An ideal 10 dB attenuator is added in front of a load that has a 2.00:1 VSWR. What is theresulting VSWR of the load + attenuator?a) 1.07:1b) 2.10:1c) 12.0:19. What is the thermal noise power in a 1 MHz bandwidth when the system temperature is 15degrees Celsius (assume gain and noise figure are 0 dB)?a) -114.0 dBm (in a 1 MHz bandwidth)b) -114.0 dBmc) -114.0 dBm/Hz10. Two equal amplitude tones have a power of +10 dBm, and generatea pair of equalamplitude 3rd-order intermodulation products at -20 dBm. What is the 2-tone, 3rd-order intercept point (IP3) of the system?a) +40 dBmb) +25 dBmc) +20 dBmRF Quiz #31. What is a primary advantage to using 90 degree (quadrature) hybrid couplers in amplifierdesigns?a) Wider bandwidth possibleb) Low noise figurec) Input/output impedance not dependent on devices as long as device impedances are equal 2. Why is there a frequency term in the equation for free-space path loss?a) There is no frequency termb) Atmospheric absorptionc) Antenna geometry requires it3. If an amplifier has a noise temperature of 60K, what is its noise figure for an ambienttemperature of 290K?a) 8.0 dBb) 80 dBc) 0.82 dB4. What is a primary advantage of offset-quadrature-phase-shift-keying (OQPSK) over standard QPSK?a) Greater data rates possibleb) Greater spectral efficiencyc) More constant envelope power5. A mixer has the following input frequencies: RF = 800 MHz, LO = 870 MHz. The desired output frequency is 70 MHz. What is the image frequency?a) 940 MHzb) 1670 MHzc) 140 MHz6. What is the spurious-free dynamic range of a system with IP3 =+30 dBm and a minimumdiscernible signal (MDS) level of -90 dBm?a) 80 dBb) 120 dBc) 60 dB7. A spectrum analyzer displays a component at 10 MHz @ 0 dBm, 30 MHz @ -10 dBm, 50 MHz@ -14 dBm, 70 MHz @ -17 dBm, and all of the other odd harmonics until they disappear intothe noise. What was the most likely input signal that caused the spectrum? a) A 10 MHz square wave (0 Vdc)b) A 10 MHz triangle wave (0 Vdc)c) A 10 MHz cosine wave (0 Vdc)8. On which side of a rectangular waveguide is an E-bend made? a) The long dimensionb) The short dimensionc) The inside9. During a network analyzer calibration, why are both a short circuit and an open circuit used?a) They average to 50 ohms in an RF systemb) To determine the characteristic impedance of the measurement system c) Both are easy to produce to at high accuracy10. What is the first harmonic of 1 GHz?a) 1 GHzb) 2 GHzc) 10 GHzRF Quiz #4 1. Which of the following can cause frequency intermodulation products in a system? a) Only semiconductor junctionslike diodes and transistors (amplifiers) b) Cable connectors, bolted or riveted antenna panels, isolators and circulators c) Botha) and b)2. What is the melting temperature of standard 60/40, tin/lead solder? a) 100?C (212?F)b) 250?C (482?F)c) 186?C (386?F)3. What is the frequency band for the 900 MHz GSM cellular band? a) Tx: 880-915 MHz / Rx: 925-960 MHzb) Tx: 824-849 MHz / Rx: 869-894 MHzc) There is no 900 MHz GSM band4. What does GSM stand for?a) General System for Mobile phonesb) Greater Spectrum for Mobile phonesc) Global System for Mobile Communication5. What does POTS stand for (in communications)?a) Plain Old Telephone Systemb) PersOnal Telephony Systemc) Personal Orbital & Terrestrial Satellite6. Which of these pairs of materials in the triboelectric series have the greatest charge transfer potential?a) Silk & Woolb) Rubber Balloon & Celluloidc) Glass & Hard Rubber7. Along which side of rectangular waveguide is an "E" bend made?a) Longer sideb) Shorter sidec) "E"ither side8. What is the lowest modulation index at which an FM carrier is suppressed?a) 2.40b) , (3.1416)c) Only AM carriers can be suppressed9. How much current is required through the human body to cause an onset to muscular paralysis during electrocution?a) Voltage is the culprit during electrocution, not currentb) 21 mAc) ? amp10. At what frequency is electromagnetic energy maximally absorbed due to oxygen in the atmosphere?a) 22 GHzb) Only water in the atmosphere absorbs electromagnetic energyc) 63 GHzRF QUIZ #5This quiz tests your recognition of logos from companies* that are leaders in the RF industry. In some cases, part of the standard logo was cropped because it had the company name included. Printing out this page to fill in the blanks is probably the best way to go about this puzzle.Hover your cursor over a logo to see a hint as to what type of product it manufactures., American____________________________Technical _ _ Ceramics (ATC), Piconics____________________________, Channel _ _ Microwave, Marki Microwave ____________________________ , Scientific Atlanta _ _ , Anadigics____________________________, National Instruments _ _, Remec____________________________, Analog Devices _ _ , Datel, Andrew ____________________________ Corporation _ _ , Hittite Microwave ____________________________ , Delta _ _ , Power Cube, Agilent ____________________________ Technologies _ _ , Synergy ____________________________Microwave _ _ , Power One, Cypress ____________________________ Semiconductor _ _ , Connecticut ____________________________Microwave _ _ , Miteq____________________________, Vicor _ _ , NationalSemiconductor ____________________________ , Maury Microwave _ _ , Cinch____________________________, Stanford _ _ Microdevices, Huber+Suhner ____________________________ , Johanson _ _ Dielectrics ____________________________ , Sage Labs _ _ , Ansoft, Atlantic ____________________________Microwave _ _ , Intusoft, Dallas ____________________________Semiconductor _ _ , MerrimacIndustries ____________________________, Applied Radio _ _ Labs, Texas ____________________________ Instruments _ _ , Trilithic , Rohde & Schwarz, Voltronics, GeneralMicrowave , Dielectric Laboratories, RF Micro Devices, GHz Technology _____________________________ _RF Quiz #6:Wireless Communications Fundamentals1. Which of the following WLAN standards is on a different frequency band than the others?a) 802.11ab) 802.11bc) 802.11gd) 802.11n2. What does the term "ruggedness" refer to in wireless power amplifiers? a) Ability to withstand thermal stressb) Ability to withstand mechanical stressc) Ability to withstand load mismatchd) All the above3. Which FCC regulation governs the unlicensed ISM band?a) Part 15b) Chapter 11c) 815.00d) Subsection 114. In which semiconductor technology are the majority of cellphone PAs manufactured?a) Si/SiCMOSb) GaNc) GaAs/InGaPd) SiGe5. What is a major advantage of Low Temperature Co-fired Ceramic (LTCC) substrates?a) Densely integrated passive componentsb) Better thermal dissipationc) Lower bill of materialsd) All the above6. Which phone standard supports the highest data rate?a) iDENb) GPRSc) EDGEd) GSM7. Which component is typically not part of a front-end module (FEM)?a) Power amplifierb) Filterc) Switchd) Controller8. Which two systems are most likely to experience concurrent operation problems? a) WLAN + GSMb) Bluetooth + WLANc) GSM + W-CDMAd) Bluetooth + AMPS9. An isolator is typically required at the output of the PA for which transmitter system a) EDGEb) Bluetoothc) GSMd) CDMA/W-CDMA10. What is the commonly claimed nominal operational range for Bluetooth? a) 10 mb) 32.8 ftc) 1.057x10^-15 lt-yrd) All the aboveRF Quiz #7: Radar Fundamentals1. What is a “radar mile?”a) 1 nautical mileb) 1 statute milec) 12.36 μs2. Which best describes a bi-static radar?a) Fixed transmitter and fixed receiver at different locationsb) Uses static electricity for both transmitted and received signalsc) Only detects fixed (non-moving) targets3. What is a radar cross-section (RCS)?a) An engineering isometric drawing showing a slice through the equipment rack(s)?b) A target’s reflection coefficient relative to a perfectly reflecting spherical surface of 1 m^2cross-sectionc) The plane through which a radar signal passes through a target 4. What are common units of radar cross-section (RCS)? a) dBsmb) dBrcsc) dBm5. Who is known as ”The Father of Radar?”a) Robert Watson-Wattb) Walter Eugene O'Reillyc) Albert Einstein6. Which flying (movement) condition will always result in a Doppler speed of 0 m/s?a) Perfectly constant speed into/out of the antenna boresightb) Perfect concentric circle around antenna at constant altitude c) Speeds at integer multiples of antenna rotation rate 7. What does “MTI” stand for?a) Multiple Target Indicationb) Mean Time Intervalc) Moving Target Indication8. Synthetic Aperture Radar (SAR) radar is mostly likely to be located on which platform?a) Police carb) Shipc) Airplane9. Which feature of a “stealth” aircraft is most responsible for its low observability?a) Radar absorbent paintb) Multi-faceted surfacesc) Minimal use of metals in airframe10. What kind of radar did the webmaster of RF Cafe work on while in the U.S.A.F?a) MPN-14b) RDR-12c) NEXRADRF Quiz #8: Hallmark Decades in Electronics1. In which decade was the transistor invented? a) 1940sb) 1950sc) 1960s2. In which decade was the telegraph invented? a) 1810sb) 1840sc) 1870s3. In which decade was the Internet first implemented? a) 1950sb) 1960sc) 1970s4. In which decade was the first solid state integrated circuit demonstrated?a) 1950sb) 1960sc) 1970s5. In which decade were the first successful diode and triode vacuum tubes invented?a) 1880sb) 1890sc) 1900s6. In which decade was the telephone invented? a) 1850sb) 1860sc) 1870s7. In which decade was the AEEE (now the IEEE) founded? a) 1880sb) 1910sc) 1940s8. In which decade with the first transatlantic radio broadcast occur?a) 1880sb) 1890sc) 1900s9. In which decade was the SPICE simulator introduced? a) 1960sb) 1970sc) 1980s10. In which decade was the ARRL founded?a) 1910sb) 1920sc) 1930sRF Quiz #9: A Smorgasbord of RF Topics1. Where did Bluetooth? get its name?a) Nobody really knowsb) In honor of Harald Bl?tand, once king of Denmark c) In honor ofits developer, “Big Blue” (IBM)d) From a Muppets characters by the same name2. Where did ZigBee get its name?a) Nobody really knowsb) From the zigzag path of a beec) Named after the comic strip character, Ziggyd) From the German phrase “sie gabe,“ meaning, “it just works” 3. Who is credited with conceiving of spread spectrum radio communications?a) Dr. Andrew Viterbib) Qualcommc) Actress Hedy Lamarrd) Kinch, the radio operator of Hogan’s Heroes4. What is meant by the front-to-back ratio of a Yagi antenna?a)The physical size of the front half of the antenna vs. the back half b) The number of driven elements vs. number of director elements c) Powerradiated in the front main lobe vs. power in opposite direction d) The weight proportion of the front half of the antenna vs. the back half 5. In an FM modulator with a 10 kHz deviation and a 5 kHz maximum modulating frequency, what is the total occupied bandwidth?a) 10 kHzb) 15 kHzc) 20 kHzd) 30 kHz6. Which WLAN standard provides the highest data rate? a)IEEE802.11a (5.1 GHz RF)54Mbpsb) IEEE802.11b (2.4 GHz RF)11Mbpsc) IEEE802.11g (2.4 GHz RF)54Mbpsd) IEEE802.11n (2.4 GHz RF)100Mbps+7. Why might the mounting orientation of a surface mount capacitor affect frequency response? a) The plates in the body could be either parallel to or perpendicular to the PCB, affecting couplingb) Adhesion is usually better in one orientationc) Conductive epoxy adhesion is usually better in one orientationd) Orientation makes no difference8. If you were handed an unprocessed wafer of gallium arsenide (GaAs), silicon (Si), silicon-germanium (SiGe), and gallium nitride。

射频工程师面试问题及参考答案

射频工程师面试问题及参考答案1.射频线一般走多宽，微带线一般如何处理。

差分线怎么走，线间距一般是多少。

-------------完全根据你选择的叠层结构，介质的介电常数，走的层和参考层来决定（当然还有铜厚，绿油厚度，间距等），随便拿个阻抗控制软件算下就知道了。

没人会闲的推公式玩吧，没有意义。

微带线的clearance最好两倍线宽，如果不够，按共面波导算。

差分线尽量等长等距，间距一倍到两倍线宽都行。

但是要注意一下几点：a.走线长度，如果板子上的走线太长，需要考虑损耗的影响了，所以尽量不要走太细。

b.不连续节点，如果设计中串联件太多，可以考虑走粗点，减小不连续节点，比如把微带变成共面波导。

当然坏处就是引入了一个容限的变量，阻抗分布的散度会变大。

c.板厂的容限，算出来的都是理想的，需要考虑实际生产的限制，比如你走60um的线有的板厂做不出来。

最后唠叨一句，阻抗控制可以让板厂帮忙，毕竟理论和实际是有差距的。

2.PA供电一般走多宽，W和GSM分别都是什么范围。

-------------可能很多人会直接给个数，比如1mm 或者0.8mm之类的。

其实我们为什么要走宽电源线，根本原因是减少不必要的压降，使得PA工作在过低的电压条件下，降低性能。

压降怎么来的，那就是PA工作的直流电流乘以走线的电阻。

走线电阻是50mohm，GSM DC电流2A，那压降就0.1V。

a. 走线电阻有关的参数是，铜厚，线宽，线长。

b. PA的直流电流？这个。

50ohm的时候和负载失配的时候区别很大。

GSM失配的时候可以到2A甚至更高（工作slot的峰值）。

所以对于这个走线的评估应该是，首先看器件spec了解需要工作的DC 电流，然后工作电压的允许压降，VBAT走线的线长，最后知道要走多宽。

3.WCDMA及TD的输出端加的SAW的作用主要作用是什么。

-------------？？这个是说PA输入端的那个SAW吧？PA输入端加SAW很好理解，就是因为PA的非线性等于一个混频器，W、TD的Transceiver 里面的DA也不干净，所以要在混频前滤掉。

射频基础助理工程师考试题.doc

射频基础考试题（共100分）分支机构名称J ___________ 员工姓名; _____________ 得分J ______________ 填空题（共40分）＜每题2分〉1.移动通信射频指的是VHF （米）波和UHF （分米）波波段;2.1G 指的TACS 制式，2G 指的GSM900/1800 和CDMA800 制式:3G指的TD-SCDMA制式、WCDMA制式和CDMA2000制式;3.GSM手机发射功率2W为IdBm，基站输出功率46dBm为4QW;4.GSM规范中，最大时间提前量TA=63bit，推算小区覆盖半径为迈Km;5.G网设计中选用信道作为发射参考功率，通常该信道不进行功率控制;6.GSM中射频调制采用GMSK调制，EDGE采用8PSK调制7.移动通信电波在自由空间中传播是扩散损耗,在金属表面传播由于趋肤效应会产生热损耗;8.两个载频fdaf2，其三阶互调产物公式为2fl-f2和2f2-fl。

9.半波偶极子天线增益2.1 dBi,.或0 dBd10.当基站天线增益相同时，频率越低其天线长度越长。

11、电压驻波比越大反射损耗越i 。

12、GSM规范中，工程上同频干扰保护比C/I3 （12 ）13、GSM规范中，每个TDMA定义为一个载频，每载频包含（8 ）个信道，每载波间隔为（200 ） KHZo14、GSM系统跳频有（射频跳频）（基带跳频）两种方式。

15、WCDMA载波宽度为（5） MHZ。

16、3G支持的高速运动、步行和室内环境的数据业务最高速率分别为（144Kbit/S、384 Kbit/S、2 Mbit/S k17、TD-SCDMA系统是一个（TDD ）双工系统。

18、某设备带外杂散指标为一67 dBm/lOOkHz，则相当于（一64 ）dBm/200kHz。

19、通信系统屮采用的“先建立，后断开”的切换方式称为（软切换），“先断幵，后建立”的切换方式称为（硬切换）。

(完整版)射频试题(判断选择计算-含答案)

判断题：1、无耗传输线终端短路，当它的长度大于四分之一波长时，输入端的输入阻抗为容抗，将等效为一个电容。

2、无耗传输线上驻波比等于1时，则反射系数的模等于0。

3、阻抗圆图上，|Γ|=1的圆称为单位圆，在单位圆上，阻抗为纯电抗，驻波比等于无限大。

4、只要无耗传输终端接上一个任意的纯电阻，则入射波全部被吸收，没有反射，传输线工作在匹配状态。

5、在传输线上存在入射波和反射波，入射波和反射波合成驻波，驻波的最大点电压值与最小点上的电压值的比即为传输线上的驻波比。

6、导纳圆图由等反射系数圆、等电抗圆和等电阻圆组成，在一个等电抗圆上各点电抗值相同。

7、圆波导的截止波长与波导的截面半径及模式有关，对于TE11模，半径越大，截止波长越短。

9、在矩形谐振腔中，TE101模的谐振频率最小。

10、同轴线是TEM传输线，只能传输TEM波，不能传输TE或TM波。

11、矩形波导传输的TE10波，磁场垂直于宽边，而且在宽边的中间上磁场强度最大。

12、圆波导可能存在“模式简并”和“极化简并”两种简并现象。

13、矩形波导中所有的模式的波阻抗都等于377欧姆。

14、矩形谐振腔谐振频率和腔体的尺寸与振荡模式有关，一般来讲，给定一种振荡模式，腔体的尺寸越大，谐振频率就越高。

15、两段用导体封闭的同轴型谐振腔，当它谐振在TEM模时，其长度等于半波长的整数倍。

16、对称振子天线上的电流可近似看成是正弦分布，在天线的输入端电流最大。

17、对称振子天线既可以作发射天线，也可以作接收天线，当它作为发射天线时，它的工作带宽要比作为接收天线时大。

18、天线阵的方向性图相乘原理指出，对于由相同的天线单元组成的天线阵，天线阵的方向性图可由单元天线的方向性图与阵因子相乘得到。

19、螺旋天线的工作模式有法向模、轴向模和边射模三种，其中轴向模辐射垂直极化波。

射频面试试题

第一部分：1. 理想空间，微波的波长λ与其频率f 的关系是什么？答案：λ=c/ f2. 在介质中传输的微波波长λ1 与在空气中传输的微波波长λ2 关系是什么？答案：λ2=（介质常数的2次方根）×λ 13. 色散波（TE 波和TM 波）的相速是大于光速的，这是不是违背了相对论的观点？为什么？第二部分：1. 说两端口网络散射参数即S 参数的物理意义。

书本答案：S11在2端口匹配的情况下1端口反射系数，S12在2端口匹配的情况下2端口到1端口的传输射系数 S22在1端口匹配的情况下2端口反射系数S11在1端口匹配的情况下1端口到2端口传输射系数 2. 什么是反射系数？驻波系数和反射系数有何关系？书本答案：反射系数T是反射功率与入射功率之比，vswr=（1+T）/（1-T） 3. 若负载阻抗为ZL ，传输线特性阻抗为Z0 ，则求电压驻波比为多少？答：反射系数F=(ZL-Z0)/(ZL+Z0)；VSWR=（1+|F|）/(1-|F|);3. 在阻抗圆图上，从源向负载方向移动和从负载向源方向移动，该如何转源图？答案：从源向负载方向移动逆时针；从负载向源方向移动顺时针4. 在阻抗圆图中，圆图旋转一周，代表多少波长？答案：0.5个波长5. 源阻抗为10 欧，负载阻抗为40 欧，如果用四分之一波长阻抗变换器来进行阻抗匹配，则应在源和负载之间插一段特性阻抗为多少的四分之一波长的传输线？答案：20欧姆；第三部分：1. 天线增益dBd 和dBi 各代表何含义，他们之间有何关系？dbm、dbc、db？答案：dBi和dBd是考征增益的值（功率增益），两者都是一个相对值，但参考基准不一样。

dBi的参考基准为全方向性天线，dBd的参考基准为偶极子，所以两者略有不同。

一般认为，表示同一个增益，用dBi表示出来比用dBd表示出来要大2. 15。

例如，对于一个面增益为16dBd的天线，折合后为18.15dBi;dBm，是一个考征功率绝对值的值，计算公式为：10lg（P功率值/1mw），例如社发射功率P=1mw，测折合为dBm后就是0dBm；如是P=40W，则从10lg(40000)= 10lg4+10lg10+10lg1000=46dBm；dB,是一个表征相对值的值，当考虑甲的功率相比乙功率大或小多少个dB时，按下面公式计算：10lg(甲/乙)；如甲的功率比乙的大一倍，那么就是3个dB；dBc，他也是一个表示功率相对值的单位，与dB的计算方法完全一样；一般来说，dBc是相对于载波功率而言的，在许多情况下，用来度量与载波功率的相对值，如用来度量干扰（同频干扰、互调干扰、交调干扰、带外干扰等），以及耦合、杂散等的相对量值。

射频工程师面试题

射频工程师面试题
射频工程师是电子工程领域中的一个重要职位，负责设计和优化射
频电路，应用于无线通信系统、雷达技术等领域。

面试射频工程师的
时候，通常会提问一些与射频工程相关的问题，以评估面试者的专业
知识和能力。

以下是一些常见的射频工程师面试题，希望能够对您有所帮助：
1. 请介绍一下射频工程的基本原理。

2. 什么是驻波比？如何测量驻波比？
3. 能否解释一下失配损耗是什么？如何解决失配损耗问题？
4. 请简要说明射频工程师在无线通信系统设计中的角色和职责。

5. 描述一下常用的射频组件和器件，以及它们在射频电路设计中的
作用。

6. 什么是天线的阻抗匹配？为什么阻抗匹配对射频系统性能至关重要？
7. 请详细描述分立和集成射频电路的优缺点以及适用场景。

8. 请列举一些常见的射频信号调制和解调方式，并简要说明其原理。

9. 在射频电路设计中，如何降低功耗和噪声？
10. 请介绍一下负载稳定性的概念，并解释为什么负载稳定性很重要。

以上题目涵盖了射频工程师面试过程中的一些基本知识点，面试者可以根据这些问题来准备和复习相关的知识。

当然，在面试过程中还可能会有其他更具体的问题，所以面试者还需要对自己的专业领域和工作经验有充分的了解。

射频工程师是一个需要广泛知识和实践经验的职位，能够回答这些问题并展示出丰富的射频工程知识和解决问题的能力将会对面试结果产生积极的影响。

最后，祝您在面试中取得好的成绩！。

无线射频覆盖工程师考试题(终稿)含答案

射频基础知识考试题2009.09 一．填空题（共40分）< 每空1分>1．2．GSM手机发射功率，基站输出功率46dBm为3．推算小区覆盖半径为5（广播控制）信道作为发射参考功率，通常该信道不进行（功率）控制。

6． GSM中射频调制采用（ GMSK ）调制，EDGE采用（ 8PSK ）调制。

4．作为扩频系统抗干扰能力的衡量标的概念来志，引入了“处理增益”GP描述，其定义为G P=）在金属表面传播由于趋肤效应会产生61和f，其三阶互调产物公式为7.频率越低其天线长度越8．。

9．GSM规范中，工程上同频干扰保护比C/I≥（12 dB ）10. GSM规范中，每个TDMA定义为一个载频，每载频包含（8 ）个信道，每载波间隔为（200 ）KHZ。

11. GSM系统跳频有（射频跳频）（基带跳频）两种方式。

12、WCDMA载波宽度为（5）MHZ。

13、3G支持的高速运动、步行和室内环境的数据业务最高速率分别为（144Kbit/S、384 Kbit/S、 2 Mbit/S ）。

14、TD-SCDMA系统是一个（TDD ）双工系统。

15、某设备带外杂散指标为－67 dBm/100kHz,则相当于（－64 ）dBm/200kHz。

16、通信系统中采用的“先建立，后断开”的切换方式称为（软切换），“先断开，后建立”的切换方式称为（硬切换）。

17、由于衰落具有频率、时间和空间的选择性，因此分集技术主要包括（空间分集）、（频率分集）、（时间分集）和（极化分集）。

18、接收机除接收有用信号外，还能收到其他频率的无用信号。

这种对其他无用信号的“响应”能力通常称为（“杂散响应”）；当无用信号足够强时，会使接收机输出端噪声显著增加，相当于接收机灵敏度下降；严重时，会使接收机完全阻塞而无法正常工作，这种现象称为（接收机灵敏度抑制或强干扰阻塞）。

19、无方向性天线也称为全向天线，通常是指点源各向通性天线和半波振子天线，它们也是各类有方向天线用以比较的标准天线。

京信通讯射频考试(带答案)

射频基础知识考试题考试时间：90分钟姓名：成绩：一、填空题（每空1分，共28分）1．在移动通信传播环境中，由于在电波传播路径上受到建筑物及山丘等的阻挡所产生的损耗为慢衰落，它遵从对数正态分布；由于多径传播而产生的衰落损耗为快衰落，它遵从瑞利分布。

2．工作频率为1800Mhz的对称半波振子长度为 8.33 cm。

3．-20dBm= 0.01 mW；0dBm+0dBm= 3 dBm；27dBi= 24. 85 dBd；33dBm-27dBm=1.5 W。

4. 京信公司某5W干放技术指标表明，当测试功率为+22dBm时，三阶互调产物≤-36dBm，则相对的互调产物电平为 58 dBc。

5.移动通信网络中，引入直放站后，直放站会提高施主基站噪声电平，降低施主基站接收机灵敏度。

6.6dB耦合器的直通口端功率分配比占输入功率 75 ％，当输入1W时，直通口端的输出功率为 28.75 dBm7．GSM系统中938.8MHz对应的频点号为 19 ；WCDMA系统中2142.6 MHz 对应的频点号为 10713 ； CDMA系统中201号载频的下行频率是 876.03 MHz；TDSCDMA系统中10120号载频的频率是 2024.0 MHz。

8．无线信号在水面上传播比在空气中传播的损耗小，无线信号的频率越高，在空气中传播的损耗越大，绕射损耗大。

9．某天线 ODP-036R15-DF,在天线正中心远处增益为 15dBi ；在天线正中心偏18°的远处区域，增益约为 12dBi 。

10．通信系统中的自然界热噪声计算公式为P热噪声＝ KTB 。

11. 无方向性天线也称为全向天线，通常是指点源各向通性天线和半波振子天线，它们也是各类有方向天线用以比较的标准天线，天线增益 G = η*D：其中η与D分别是该天线的效率与方向性系数。

12．自由空间无线信号传播公式 32.4+20lgF(MHz)+20lgD(Km)，当空间距离增加两倍时，空间损耗增加 12dB 。

射频工程师面试题

射频工程师面试题射频工程师是在通信领域中扮演重要角色的专业人员，他们主要负责设计、开发和维护射频系统，以确保无线通信的稳定和高效。

在面试过程中，候选人会被问及各种与射频技术和工程相关的问题，以评估其专业知识和能力。

以下是一些常见的射频工程师面试题：1. 请解释什么是射频？射频（Radio Frequency）是指频率在300 Hz到300 GHz之间的电磁波信号。

在无线通信中，射频用于传输和接收信息。

2. 什么是驻波比（VSWR）？驻波比是射频工程师经常用来描述电路传输线的质量的一个重要参数。

它表示电路传输线反射的能量与输入的能量之间的比值。

3. 如何解决驻波比过高的问题？可以采取以下几种方法来降低驻波比：- 使用匹配网络- 使用反射阻抗转换器- 更换适当的传输线- 调整天线的位置和方向4. 请解释射频功率放大器的工作原理。

射频功率放大器用于将输入信号的功率放大到特定的输出水平。

它由输入匹配网络、功率放大器元件（如晶体管）和输出匹配网络组成。

输入信号通过输入匹配网络进入功率放大器，经过放大后，通过输出匹配网络输出。

5. 请简要描述射频滤波器的作用。

射频滤波器用于选择特定频段的信号，并将其他频段的信号阻止。

它主要用于限制带宽和抑制杂散信号。

6. 射频传输线有哪些常见的类型？常见的射频传输线类型包括：- 微带线（Microstrip）：适用于高频率和高密度应用- 同轴电缆（Coaxial Cable）：适用于中频和高频应用- 双平行线（Twin-lead）：适用于低频应用- 平面波导（Stripline）：适用于高频和宽带传输7. 如何计算射频天线的增益？射频天线的增益可以通过以下公式计算：增益（dB）= 10 * log10（功率输出 / 功率输入）。

8. 请解释功率分贝（dB）的含义。

功率分贝（dB）是用于描述功率比例的对数比单位。

它用于表示功率放大、衰减、增益等情况，其中1 dB表示10的对数比。

射频面试题精选题目总结

1、PCB 上微带线阻抗用什么软件计算。

微带线的阻抗和哪几个因素有关。

不同频率，线特征阻抗是否和频率相关?用ADS 里面的工具，在原理图上按以下途径找到Tools -> LineCalc -> StartLinecalc，微带线的阻抗和基板厚度、基板相对介电常数、微带线的宽度等有关不同频率，线特征阻抗和频率无关。

2. 级联NF 的公式，电阻PI 的NF，Mixer 的NF，普通射频放大器的NF 值的范围。

公式参照课本。

电阻的NF等于其插损，无源混频器的NF等于根据其变频损耗，大概在7db，普通放大器变化范围比较大，一般4db到8db，当然也跟频段有关。

3. IP3IIP3(IIP3)1(IIP3)2(IIP3)3一般而言三阶交调点是比较难测的，因为不好找到两个频率源，和合路设备，所以一般根据p1db+10db即可测量。

4、1dB5.值计算方法。

eg:要实现3db的衰减网络可以用292, 17.6,292欧姆的PI型等效网络。

6. 电阻类型、值系列、使用时哪些指标需要降额使用、不同封装的电阻的额定功耗。

精度为5％的碳膜电阻，1%的是金属膜电阻。

有英制与米制，实际上现在用的大都都是英制，如0805等。

贴片电阻的标准封装及额定功率国内贴片电阻的命名方法：1、5%精度的命名：RS-05K102JT2、1％精度的命名：RS-05K1002FTR －表示电阻S －表示功率0402是1/16W、0603是1/10W、0805是1/8W、1206是1/4W、1210是1/3W、1812是1/2W、2010是3/4W、2512是1W。

05 －表示尺寸(英寸)：02表示0402、03表示0603、05表示0805、06表示1206、1210表示1210、1812表示1812、10表示1210、12表示2512。

K －表示温度系数为100PPM,102－5％精度阻值表示法：前两位表示有效数字，第三位表示有多少个零，基本单位是Ω，102＝10000Ω＝1KΩ。

射频面试题

TOD射频笔试题
一．填空题：
（1）在smith阻抗圆图中，阻抗的实部越大，点的位置（），品质因数越大，圆弧位置（）。

（2）写出VSWR的公式：VSWR=（）。

（3）如果电源阻抗为8欧姆，负载阻抗为50欧姆，利用1/4匹配线进行匹配，匹配线的特征阻抗为（）欧姆。

（4）S参数中S21与S12分别代表的含义（）。

（5）制作电路板中，微带线的哪三因素对特征阻抗有明显影响：（）、（）、（）。

二．问答题：
（1）如何设计功率放大器？写出相关步骤
（2）在smith圆图中，如何把从第一象限的阻抗匹配到50欧姆？画出示意图
（3）请简述锁相环基本构成与工作原理，各部分器件的作用。

（4）描述下通信系统的组成图。

（5）谈谈RF读卡器工作原理。

射频工程师测试题

射频⼯程师测试题射频⼯程师测试题RF Quiz #11. What is the impedance of free space?377ou2. What happens to the noise figure of a receiver when a 10 dB attenuator is added at the input?a) Noise figure increases by 10 dBb) Noise figure decreases by 10 dBc) Noise figure doesn't change3. An RF system has a linear throughput gain of +10 dB and an output 3rd-order intercept point (OIP3) of +30 dBm. What is the input 3rd-order intercept point(IIP3)? a) +20 dBmb) +40 dBmc) +30 dBm4. Which filter type has the greatest selectivity for a given order(i.e., N=5)? a) Besselb) Chebychev (ripple=0.1 dB)c) Butterworth5. Which mixer spurious product is a 5th-order product?a) 1*LO + 5*RFb) 6*LO - 1*RFc) 3*LO - 2*IF6. A 2.8 GHz oscillator is phase-locked to a 10 MHz reference oscillator that has a single-sided phase noise of -100 dBc at 1 kHz offset. What is the single-sided phase noise of the 2.8 GHz oscillator at 1 kHz offset?a) -48.6 dBcb) -100 dBcc) -51.1 dBc7. What is the power of a 2 Vpk-pk sine wave across a 50 ohm load? a) -20.0 dBmb) +10.0 dBmc) +19.0 dBm8. Which 2-port S-parameter is commonly referred to as "reverse isolation" in an amplifier? a) S21b) S22c) S129. What are the minimum and maximum combined VSWR limits at an interface characterized bya 1.25:1 VSWR and a 2.00:1 VSWR?a) 1.75:1 (min), 2.25:1 (max)b) 1.60:1 (min), 2.50:1 (max)c) 0.75:1 (min), 3.25:1 (max)10. An ideal directional coupler has a directivity of 25 dB and an isolation of 40 dB. What is itscoupling value? I=D+Ca) 65 dBb) 40 dBc) 15 dBRF Quiz #2 1. On a Smith chart, what does a point in the bottom half of the chart represent? a) An inductive impedanceb) A capacitive impedancec) Power saturation2. While we're on the subject of Smith charts, what is the impedance of the point at the far leftedge of the center horizontal line?a) Infinite ohms (open circuit)b) Zero ohms (short circuit)c) 50 ohm match3. A single-conversion downconverter uses a high-side localoscillator (LO) to translate the inputradio frequency (RF) to an intermediate frequency (IF). Willspectral inversion occur at IF? a) Yes, alwaysb) No, neverc) Sometimes4. What happens to the noise floor of a spectrum analyzer when the input filter resolutionbandwidth is decreased by two decades?a) 20 dB increaseb) 20 dB decreasec) 40 dB decrease5. What is a primary advantage of a quadrature modulator?a) Low LO power requiredb) Four separate outputsc) Single-sideband output6. What is meant by dBi as applied to antennas?a) Isolation in decibelsb) Physical size relative to intrinsic antennasc) Gain relative to an isotropic radiator7. What is the power dynamic range of an ideal 12-bit analog-to-digital converter (ADC)? a) 36.12 dBb) 120 dBc) 72.25 dB8. An ideal 10 dB attenuator is added in front of a load that has a 2.00:1 VSWR. What is theresulting VSWR of the load + attenuator?a) 1.07:1b) 2.10:1c) 12.0:19. What is the thermal noise power in a 1 MHz bandwidth when the system temperature is 15degrees Celsius (assume gain and noise figure are 0 dB)?a) -114.0 dBm (in a 1 MHz bandwidth)b) -114.0 dBmc) -114.0 dBm/Hz10. Two equal amplitude tones have a power of +10 dBm, and generatea pair of equalamplitude 3rd-order intermodulation products at -20 dBm. What is the 2-tone, 3rd-order intercept point (IP3) of the system?a) +40 dBmb) +25 dBmc) +20 dBmRF Quiz #31. What is a primary advantage to using 90 degree (quadrature) hybrid couplers in amplifierdesigns?a) Wider bandwidth possibleb) Low noise figurec) Input/output impedance not dependent on devices as long as device impedances are equal 2. Why is there a frequency term in the equation for free-space path loss?a) There is no frequency termb) Atmospheric absorptionc) Antenna geometry requires it3. If an amplifier has a noise temperature of 60K, what is its noise figure for an ambienttemperature of 290K?a) 8.0 dBb) 80 dBc) 0.82 dB4. What is a primary advantage of offset-quadrature-phase-shift-keying (OQPSK) over standard QPSK?a) Greater data rates possibleb) Greater spectral efficiencyc) More constant envelope power5. A mixer has the following input frequencies: RF = 800 MHz, LO = 870 MHz. The desired output frequency is 70 MHz. What is the image frequency?a) 940 MHzb) 1670 MHzc) 140 MHz6. What is the spurious-free dynamic range of a system with IP3 =+30 dBm and a minimumdiscernible signal (MDS) level of -90 dBm?a) 80 dBb) 120 dBc) 60 dB7. A spectrum analyzer displays a component at 10 MHz @ 0 dBm, 30 MHz @ -10 dBm, 50 MHz@ -14 dBm, 70 MHz @ -17 dBm, and all of the other odd harmonics until they disappear intothe noise. What was the most likely input signal that caused the spectrum? a) A 10 MHz square wave (0 Vdc)b) A 10 MHz triangle wave (0 Vdc)c) A 10 MHz cosine wave (0 Vdc)8. On which side of a rectangular waveguide is an E-bend made? a) The long dimensionb) The short dimensionc) The inside9. During a network analyzer calibration, why are both a short circuit and an open circuit used?a) They average to 50 ohms in an RF systemb) To determine the characteristic impedance of the measurement system c) Both are easy to produce to at high accuracy10. What is the first harmonic of 1 GHz?a) 1 GHzb) 2 GHzc) 10 GHzRF Quiz #4 1. Which of the following can cause frequency intermodulation products in a system? a) Only semiconductor junctionslike diodes and transistors (amplifiers) b) Cable connectors, bolted or riveted antenna panels, isolators and circulators c) Both a) and b)2. What is the melting temperature of standard 60/40, tin/lead solder? a) 100?C (212?F)b) 250?C (482?F)c) 186?C (386?F)3. What is the frequency band for the 900 MHz GSM cellular band? a) Tx: 880-915 MHz / Rx: 925-960 MHzb) Tx: 824-849 MHz / Rx: 869-894 MHzc) There is no 900 MHz GSM band4. What does GSM stand for?a) General System for Mobile phonesb) Greater Spectrum for Mobile phonesc) Global System for Mobile Communication5. What does POTS stand for (in communications)?a) Plain Old Telephone Systemb) PersOnal Telephony Systemc) Personal Orbital & Terrestrial Satellite6. Which of these pairs of materials in the triboelectric series have the greatest charge transfer potential?a) Silk & Woolb) Rubber Balloon & Celluloidc) Glass & Hard Rubber7. Along which side of rectangular waveguide is an "E" bend made?a) Longer sideb) Shorter sidec) "E"ither side8. What is the lowest modulation index at which an FM carrier is suppressed?a) 2.40b) , (3.1416)c) Only AM carriers can be suppressed9. How much current is required through the human body to cause an onset to muscular paralysis during electrocution?a) Voltage is the culprit during electrocution, not currentb) 21 mAc) ? amp10. At what frequency is electromagnetic energy maximally absorbed due to oxygen in the atmosphere?a) 22 GHzb) Only water in the atmosphere absorbs electromagnetic energyc) 63 GHzRF QUIZ #5This quiz tests your recognition of logos from companies* that are leaders in the RF industry. In some cases, part of the standard logo was cropped because it had the company name included. Printing out this page to fill in the blanks is probably the best way to go about this puzzle.Hover your cursor over a logo to see a hint as to what type of product it manufactures., American____________________________Technical _ _ Ceramics (ATC), Piconics____________________________, Channel _ _ Microwave, Marki Microwave ____________________________ , Scientific Atlanta _ _ , Anadigics____________________________, National Instruments _ _, Remec____________________________, Analog Devices _ _ , Datel, Andrew ____________________________ Corporation _ _ , Hittite Microwave ____________________________ , Delta _ _ , Power Cube, Agilent ____________________________ Technologies _ _ , Synergy ____________________________Microwave _ _ , Power One, Cypress ____________________________ Semiconductor _ _ , Connecticut____________________________Microwave _ _ , Miteq____________________________, Vicor _ _ , NationalSemiconductor ____________________________ , Maury Microwave _ _ , Cinch____________________________, Stanford _ _ Microdevices, Huber+Suhner ____________________________ , Johanson _ _ Dielectrics ____________________________ , Sage Labs _ _ , Ansoft, Atlantic ____________________________Microwave _ _ , Intusoft, Dallas ____________________________Semiconductor _ _ , MerrimacIndustries ____________________________, Applied Radio _ _ Labs, Texas ____________________________ Instruments _ _ , Trilithic, Rohde & Schwarz, Voltronics, GeneralMicrowave , Dielectric Laboratories, RF Micro Devices, GHz Technology _____________________________ _RF Quiz #6:Wireless Communications Fundamentals1. Which of the following WLAN standards is on a different frequency band than the others?a) 802.11ab) 802.11bc) 802.11gd) 802.11n2. What does the term "ruggedness" refer to in wireless power amplifiers? a) Ability to withstand thermal stressb) Ability to withstand mechanical stressc) Ability to withstand load mismatchd) All the above3. Which FCC regulation governs the unlicensed ISM band? a) Part 15b) Chapter 11c) 815.00d) Subsection 114. In which semiconductor technology are the majority of cellphone PAs manufactured?a) Si/SiCMOSb) GaNc) GaAs/InGaPd) SiGe5. What is a major advantage of Low Temperature Co-fired Ceramic (LTCC) substrates?a) Densely integrated passive componentsb) Better thermal dissipationc) Lower bill of materialsd) All the above6. Which phone standard supports the highest data rate?a) iDENb) GPRSc) EDGEd) GSM7. Which component is typically not part of a front-end module (FEM)?a) Power amplifierb) Filterc) Switchd) Controller8. Which two systems are most likely to experience concurrent operation problems? a) WLAN + GSMb) Bluetooth + WLANc) GSM + W-CDMAd) Bluetooth + AMPS9. An isolator is typically required at the output of the PA for which transmitter system a) EDGEb) Bluetoothc) GSMd) CDMA/W-CDMA10. What is the commonly claimed nominal operational range for Bluetooth? a) 10 mb) 32.8 ftc) 1.057x10^-15 lt-yrd) All the aboveRF Quiz #7: Radar Fundamentals1. What is a “radar mile?”a) 1 nautical mileb) 1 statute milec) 12.36 µs2. Which best describes a bi-static radar?a) Fixed transmitter and fixed receiver at different locations b) Uses static electricity for both transmitted and received signalsc) Only detects fixed (non-moving) targets3. What is a radar cross-section (RCS)?a) An engineering isometric drawing showing a slice through the equipment rack(s)?b) A target’s reflection coefficient relative to a perfectly reflecting spherical surface of 1 m^2cross-sectionc) The plane through which a radar signal passes through a target 4. What are common units of radar cross-section (RCS)?a) dBsmb) dBrcsc) dBm5. Who is known as ”The Father of Radar?”a) Robert Watson-Wattb) Walter Eugene O'Reillyc) Albert Einstein6. Which flying (movement) condition will always result in a Doppler speed of 0 m/s?a) Perfectly constant speed into/out of the antenna boresight b) Perfect concentric circle around antenna at constant altitude c) Speeds at integer multiples of antenna rotation rate 7. What does “MTI” stand for?a) Multiple Target Indicationb) Mean Time Intervalc) Moving Target Indication8. Synthetic Aperture Radar (SAR) radar is mostly likely to be located on which platform?a) Police carb) Shipc) Airplane9. Which feature of a “stealth” aircraft is most responsible for its low observability?a) Radar absorbent paintb) Multi-faceted surfacesc) Minimal use of metals in airframe10. What kind of radar did the webmaster of RF Cafe work on while in the U.S.A.F?a) MPN-14b) RDR-12c) NEXRADRF Quiz #8: Hallmark Decades in Electronics1. In which decade was the transistor invented? a) 1940sb) 1950sc) 1960s2. In which decade was the telegraph invented? a) 1810sb) 1840sc) 1870s3. In which decade was the Internet first implemented? a) 1950sb) 1960sc) 1970s4. In which decade was the first solid state integrated circuit demonstrated?a) 1950sb) 1960sc) 1970s5. In which decade were the first successful diode and triode vacuum tubes invented?a) 1880sb) 1890sc) 1900s6. In which decade was the telephone invented? a) 1850sb) 1860sc) 1870s7. In which decade was the AEEE (now the IEEE) founded? a) 1880sb) 1910s8. In which decade with the first transatlantic radio broadcast occur?a) 1880sb) 1890sc) 1900s9. In which decade was the SPICE simulator introduced? a) 1960sb) 1970sc) 1980s10. In which decade was the ARRL founded?a) 1910sb) 1920sc) 1930sRF Quiz #9: A Smorgasbord of RF Topics1. Where did Bluetooth? get its name?a) Nobody really knowsb) In honor of Harald Bl?tand, once king of Denmark c) In honor ofits developer, “Big Blue” (IBM)d) From a Muppets characters by the same name2. Where did ZigBee get its name?a) Nobody really knowsb) From the zigzag path of a beec) Named after the comic strip character, Ziggyd) From the German phrase “sie gabe,“ meaning, “it just works” 3. Who is credited with conceiving of spread spectrum radio communications?a) Dr. Andrew Viterbib) Qualcommc) Actress Hedy Lamarrd) Kinch, the radio operator of Hogan’s Heroes4. What is meant by the front-to-back ratio of a Yagi antenna? a)The physical size of the front half of the antenna vs. the back half b) The number of driven elements vs. number of director elements c) Powerradiated in the front main lobe vs. power in opposite direction d) The weight proportion of the front half of the antenna vs. the back half 5. In an FM modulator with a 10 kHz deviation and a 5 kHz maximum modulating frequency,what is the total occupied bandwidth?a) 10 kHzb) 15 kHzc) 20 kHz6. Which WLAN standard provides the highest data rate? a)IEEE802.11a (5.1 GHz RF)54Mbpsb) IEEE802.11b (2.4 GHz RF)11Mbpsc) IEEE802.11g (2.4 GHz RF)54Mbpsd) IEEE802.11n (2.4 GHz RF)100Mbps+7. Why might the mounting orientation of a surface mount capacitor affect frequency response? a) The plates in the body could be either parallel to or perpendicular to the PCB, affectingcouplingb) Adhesion is usually better in one orientationc) Conductive epoxy adhesion is usually better in one orientationd) Orientation makes no difference8. If you were handed an unprocessed wafer of gallium arsenide (GaAs), silicon (Si), silicon-germanium (SiGe), and gallium nitride。

射频功放电路面试题

射频功放电路面试题
射频功放电路是无线通信系统中非常重要的组成部分，以下是一些可能的射频功放电路面试题：
1.什么是射频功放电路？它的作用是什么？
2.射频功放电路中的关键组件有哪些？它们的作用是什么？
3.请描述射频功放电路的工作原理。

4.射频功放电路有哪些常见的性能指标？如何优化这些指标？
5.请解释什么是交调失真、谐波失真和互调失真，并给出解决方案。

6.在射频功放电路中，如何实现功率控制和增益控制？
7.请描述射频功放电路中的反馈控制方法。

8.请解释什么是线性度，如何提高射频功放电路的线性度？
9.什么是噪声系数和噪声功率比？它们在射频功放电路中的意义是什么？
10.请解释射频功放电路中的效率问题，并给出提高效率的方法。

11.请描述射频功放电路的调试和测试过程。

12.在射频功放电路中，如何解决散热问题？
13.请解释什么是功率合成技术，它在射频功放电路中的应用是什么？
14.什么是匹配网络？它在射频功放电路中的作用是什么？
15.在射频功放电路中，如何选择合适的元件和材料？
以上问题仅供参考，具体的面试题可能会根据不同的公司和岗位有所调整。

在准备面试时，建议对射频功放电路的相关知识进行深入了解，包括工作原理、性能指标、关键组件、优化方法等方面。

射频基础考试题(答案)

射频基础考试题（共100分）分支机构名称：员工姓名：得分：一、问答题（共64分）<第一题10分，其余每题7分>1．什么叫射频？（10分）射频是指该频率的载波功率能通过天线发射出去（反之亦然），以交变的电磁场形式在自由空间以光速传播，碰到不同介质时传播速率发生变化，也会发生电磁波反射、折射、绕射、穿透等，引起各种损耗。

在金属线传输时具有趋肤效应现象。

2．动通信1G，2G，3G能提供什么业务？（7分）1G提供模拟电话2G提供数字电话3G提供数字电话和高速数据业务3．3G ，TDD我国规定使用频段？（7分）共三段：1880~1920MHz;2010~2025MHz;2300MHz~2400MHz.4．GSM900接收机的热噪声，底噪及灵敏度之间的关系，并计算出当接收机的NF（噪声系数）=5dB时，其灵敏度为多少？（7分）(1).热噪声K.T.B=-121dBm;(2)底噪声K.T.B+NF B=-116 dBm;(3)灵敏度=底噪+C/I=-104 dBm;5．陆地移动通信中，电波传播衰落遵循哪两种分布规律，各自与哪些因素相关或无关？（7分）（1）快衰落，服从瑞利分布规律，衰落速度与移动体运动速度和信号工作频率有关；（2）慢衰落，服从对数正态分布规律，衰落速度与频率无关，与周围物体和移动体速度有关6．说出2G和3G宏小区传播损耗模式。

（7分）2G 传播模式奥村-HATA 适用频率范围为150 MHz ~1500MHz;3G 传播模式COST—231 Hata适用频率范围在1500 MHz -2300 MHz频段；7．一种移动通信室内传播损耗公式（7分）式中PL(do)为自由空间1米传输损耗；nsf为损耗因子（2.0~3.6）；FAF不同层或墙的损耗值（10~20dB）；D为距离，单位M；9．CDMA800和GSM900的干扰主要是什么干扰？对于共设台时应采取哪些措施来减少干扰？（7分）属于带外杂散干扰采取以下措施：a.增加两系统之间的距离；b.在CDMA发射系统加装滤波器来减少带外杂散辐射。

射频工程师常见面试题

射频工程师常见面试题射频工程师常见面试题（一）近年来，随着无线通信技术的快速发展，射频工程师的需求也日益增加。

因此，成为一名优秀的射频工程师，不仅需要扎实的专业知识，还要具备出色的解决问题与沟通能力。

在面试过程中，常见的射频工程师面试题主要涵盖以下几个方面。

1. 射频基础知识- 请简要介绍一下射频工程的基本概念和特点。

- 什么是射频电路？请列举一些常见的射频电路元件。

- 请解释射频信号和基带信号之间的区别。

- 请解释射频信号、中频信号和基带信号的概念，并分别给出一些实际应用。

2. 射频系统设计- 请简要介绍射频系统的设计流程。

- 请列举一些常见的射频设计指标，并解释其含义。

- 请问何为射频系统的传输线损耗？如何评估传输线的损耗？- 设计一种能在2.4GHz频段工作的射频功放，输出功率为20dBm，你将如何实现？3. 射频测试技术- 请简要介绍射频测试的基本原理和方法。

- 请列举一些常见的射频测试仪器，并解释其功能。

- 请解释射频系统中的谐波和杂散，以及它们对系统性能的影响。

- 请介绍一种常用的射频测试技术，并解释其原理。

4. 电磁兼容性与射频干扰- 请解释什么是电磁兼容性？射频干扰在其中起到了什么作用？- 请列举一些常见的射频干扰源，并阐述其产生的原因。

- 请解释射频屏蔽的基本原理，并介绍一种常用的屏蔽材料。

- 如果遇到一起射频干扰问题，你将如何解决？5. 射频通信系统- 请解释什么是SDR（软件定义无线电）以及其在射频通信系统中的应用。

- 请列举一些常见的无线通信标准，并解释其特点和应用场景。

- 请简要介绍一下蜂窝通信系统的架构和工作原理。

- 如果需要对一个蜂窝通信系统进行优化，你将从哪些方面入手？这些是射频工程师常见的面试问题，掌握这些知识将有助于你在面试中展现出对射频工程领域的了解和扎实的技术功底。

在准备面试时，建议结合自己的实际经验，多解答一些开放式问题，并学会灵活运用所学知识和解决问题的能力。

射频工程师测试题

射频工程师测试题RF Quiz #11. What is the impedance of free space?377ou2. What happens to the noise figure of a receiver when a 10 dB attenuator is added at theinput?a) Noise figure increases by 10 dBb) Noise figure decreases by 10 dBc) Noise figure doesn't change3. An RF system has a linear throughput gain of +10 dB and an output 3rd-order intercept point(OIP3) of +30 dBm. What is the input 3rd-order intercept point(IIP3)? a) +20 dBmb) +40 dBmc) +30 dBm4. Which filter type has the greatest selectivity for a given order(i.e., N=5)? a) Besselb) Chebychev (ripple=0.1 dB)c) Butterworth5. Which mixer spurious product is a 5th-order product?a) 1*LO + 5*RFb) 6*LO - 1*RFc) 3*LO - 2*IF6. A 2.8 GHz oscillator is phase-locked to a 10 MHz reference oscillator that has a single-sidedphase noise of -100 dBc at 1 kHz offset. What is the single-sided phase noise of the 2.8 GHzoscillator at 1 kHz offset?a) -48.6 dBcb) -100 dBcc) -51.1 dBc7. What is the power of a 2 Vpk-pk sine wave across a 50 ohm load? a) -20.0 dBmb) +10.0 dBmc) +19.0 dBm8. Which 2-port S-parameter is commonly referred to as "reverse isolation" in an amplifier? a) S21b) S22c) S129. What are the minimum and maximum combined VSWR limits at an interface characterized bya 1.25:1 VSWR and a 2.00:1 VSWR?a) 1.75:1 (min), 2.25:1 (max)b) 1.60:1 (min), 2.50:1 (max)c) 0.75:1 (min), 3.25:1 (max)10. An ideal directional coupler has a directivity of 25 dB and an isolation of 40 dB. What is itscoupling value? I=D+Ca) 65 dBb) 40 dBc) 15 dBRF Quiz #2 1. On a Smith chart, what does a point in the bottom half of the chart represent? a) An inductive impedanceb) A capacitive impedancec) Power saturation2. While we're on the subject of Smith charts, what is the impedance of the point at the far leftedge of the center horizontal line?a) Infinite ohms (open circuit)b) Zero ohms (short circuit)c) 50 ohm match3. A single-conversion downconverter uses a high-side localoscillator (LO) to translate the inputradio frequency (RF) to an intermediate frequency (IF). Willspectral inversion occur at IF? a) Yes, alwaysb) No, neverc) Sometimes4. What happens to the noise floor of a spectrum analyzer when the input filter resolutionbandwidth is decreased by two decades?a) 20 dB increaseb) 20 dB decreasec) 40 dB decrease5. What is a primary advantage of a quadrature modulator?a) Low LO power requiredb) Four separate outputsc) Single-sideband output6. What is meant by dBi as applied to antennas?a) Isolation in decibelsb) Physical size relative to intrinsic antennasc) Gain relative to an isotropic radiator7. What is the power dynamic range of an ideal 12-bit analog-to-digital converter (ADC)? a) 36.12 dBb) 120 dBc) 72.25 dB8. An ideal 10 dB attenuator is added in front of a load that has a 2.00:1 VSWR. What is theresulting VSWR of the load + attenuator?a) 1.07:1b) 2.10:1c) 12.0:19. What is the thermal noise power in a 1 MHz bandwidth when the system temperature is 15degrees Celsius (assume gain and noise figure are 0 dB)?a) -114.0 dBm (in a 1 MHz bandwidth)b) -114.0 dBmc) -114.0 dBm/Hz10. Two equal amplitude tones have a power of +10 dBm, and generatea pair of equalamplitude 3rd-order intermodulation products at -20 dBm. What is the 2-tone, 3rd-order intercept point (IP3) of the system?a) +40 dBmb) +25 dBmc) +20 dBmRF Quiz #31. What is a primary advantage to using 90 degree (quadrature) hybrid couplers in amplifierdesigns?a) Wider bandwidth possibleb) Low noise figurec) Input/output impedance not dependent on devices as long as device impedances are equal 2. Why is there a frequency term in the equation for free-space path loss?a) There is no frequency termb) Atmospheric absorptionc) Antenna geometry requires it3. If an amplifier has a noise temperature of 60K, what is its noise figure for an ambienttemperature of 290K?a) 8.0 dBb) 80 dBc) 0.82 dB4. What is a primary advantage of offset-quadrature-phase-shift-keying (OQPSK) over standard QPSK?a) Greater data rates possibleb) Greater spectral efficiencyc) More constant envelope power5. A mixer has the following input frequencies: RF = 800 MHz, LO = 870 MHz. The desired output frequency is 70 MHz. What is the image frequency?a) 940 MHzb) 1670 MHzc) 140 MHz6. What is the spurious-free dynamic range of a system with IP3 =+30 dBm and a minimumdiscernible signal (MDS) level of -90 dBm?a) 80 dBb) 120 dBc) 60 dB7. A spectrum analyzer displays a component at 10 MHz @ 0 dBm, 30 MHz @ -10 dBm, 50 MHz@ -14 dBm, 70 MHz @ -17 dBm, and all of the other odd harmonics until they disappear intothe noise. What was the most likely input signal that caused the spectrum? a) A 10 MHz square wave (0 Vdc)b) A 10 MHz triangle wave (0 Vdc)c) A 10 MHz cosine wave (0 Vdc)8. On which side of a rectangular waveguide is an E-bend made? a) The long dimensionb) The short dimensionc) The inside9. During a network analyzer calibration, why are both a short circuit and an open circuit used?a) They average to 50 ohms in an RF systemb) To determine the characteristic impedance of the measurement system c) Both are easy to produce to at high accuracy10. What is the first harmonic of 1 GHz?a) 1 GHzb) 2 GHzc) 10 GHzRF Quiz #4 1. Which of the following can cause frequency intermodulation products in a system? a) Only semiconductor junctionslike diodes and transistors (amplifiers) b) Cable connectors, bolted or riveted antenna panels, isolators and circulators c) Both a) and b)2. What is the melting temperature of standard 60/40, tin/lead solder? a) 100?C (212?F)b) 250?C (482?F)c) 186?C (386?F)3. What is the frequency band for the 900 MHz GSM cellular band? a) Tx: 880-915 MHz / Rx: 925-960 MHzb) Tx: 824-849 MHz / Rx: 869-894 MHzc) There is no 900 MHz GSM band4. What does GSM stand for?a) General System for Mobile phonesb) Greater Spectrum for Mobile phonesc) Global System for Mobile Communication5. What does POTS stand for (in communications)?a) Plain Old Telephone Systemb) PersOnal Telephony Systemc) Personal Orbital & Terrestrial Satellite6. Which of these pairs of materials in the triboelectric series have the greatest charge transfer potential?a) Silk & Woolb) Rubber Balloon & Celluloidc) Glass & Hard Rubber7. Along which side of rectangular waveguide is an "E" bend made?a) Longer sideb) Shorter sidec) "E"ither side8. What is the lowest modulation index at which an FM carrier is suppressed?a) 2.40b) , (3.1416)c) Only AM carriers can be suppressed9. How much current is required through the human body to cause an onset to muscular paralysis during electrocution?a) Voltage is the culprit during electrocution, not currentb) 21 mAc) ? amp10. At what frequency is electromagnetic energy maximally absorbed due to oxygen in the atmosphere?a) 22 GHzb) Only water in the atmosphere absorbs electromagnetic energyc) 63 GHzRF QUIZ #5This quiz tests your recognition of logos from companies* that are leaders in the RF industry. In some cases, part of the standard logo was cropped because it had the company name included. Printing out this page to fill in the blanks is probably the best way to go about this puzzle.Hover your cursor over a logo to see a hint as to what type of product it manufactures., American____________________________Technical _ _ Ceramics (ATC), Piconics____________________________, Channel _ _ Microwave, Marki Microwave ____________________________ , Scientific Atlanta _ _ , Anadigics____________________________, National Instruments _ _, Remec____________________________, Analog Devices _ _ , Datel, Andrew ____________________________ Corporation _ _ , Hittite Microwave ____________________________ , Delta _ _ , Power Cube, Agilent ____________________________ Technologies _ _ , Synergy ____________________________Microwave _ _ , Power One, Cypress ____________________________ Semiconductor _ _ , Connecticut ____________________________Microwave _ _ , Miteq____________________________, Vicor _ _ , NationalSemiconductor ____________________________ , Maury Microwave _ _ , Cinch____________________________, Stanford _ _ Microdevices, Huber+Suhner ____________________________ , Johanson _ _ Dielectrics ____________________________ , Sage Labs _ _ , Ansoft, Atlantic ____________________________Microwave _ _ , Intusoft, Dallas ____________________________Semiconductor _ _ , MerrimacIndustries ____________________________, Applied Radio _ _ Labs, Texas ____________________________ Instruments _ _ , Trilithic, Rohde & Schwarz, Voltronics, GeneralMicrowave , Dielectric Laboratories, RF Micro Devices, GHz Technology _____________________________ _RF Quiz #6:Wireless Communications Fundamentals1. Which of the following WLAN standards is on a different frequency band than the others?a) 802.11ab) 802.11bc) 802.11gd) 802.11n2. What does the term "ruggedness" refer to in wireless power amplifiers? a) Ability to withstand thermal stressb) Ability to withstand mechanical stressc) Ability to withstand load mismatchd) All the above3. Which FCC regulation governs the unlicensed ISM band? a) Part 15b) Chapter 11c) 815.00d) Subsection 114. In which semiconductor technology are the majority of cellphone PAs manufactured?a) Si/SiCMOSb) GaNc) GaAs/InGaPd) SiGe5. What is a major advantage of Low Temperature Co-fired Ceramic (LTCC) substrates?a) Densely integrated passive componentsb) Better thermal dissipationc) Lower bill of materialsd) All the above6. Which phone standard supports the highest data rate?a) iDENb) GPRSc) EDGEd) GSM7. Which component is typically not part of a front-end module (FEM)?a) Power amplifierb) Filterc) Switchd) Controller8. Which two systems are most likely to experience concurrent operation problems? a) WLAN + GSMb) Bluetooth + WLANc) GSM + W-CDMAd) Bluetooth + AMPS9. An isolator is typically required at the output of the PA for which transmitter system a) EDGEb) Bluetoothc) GSMd) CDMA/W-CDMA10. What is the commonly claimed nominal operational range for Bluetooth? a) 10 mb) 32.8 ftc) 1.057x10^-15 lt-yrd) All the aboveRF Quiz #7: Radar Fundamentals1. What is a “radar mile?”a) 1 nautical mileb) 1 statute milec) 12.36 µs2. Which best describes a bi-static radar?a) Fixed transmitter and fixed receiver at different locations b) Uses static electricity for both transmitted and received signals c) Only detects fixed (non-moving) targets3. What is a radar cross-section (RCS)?a) An engineering isometric drawing showing a slice through the equipment rack(s)?b) A target’s reflection coefficient relative to a perfectly reflecting spherical surface of 1 m^2cross-sectionc) The plane through which a radar signal passes through a target 4. What are common units of radar cross-section (RCS)? a) dBsmb) dBrcsc) dBm5. Who is known as ”The Father of Radar?”a) Robert Watson-Wattb) Walter Eugene O'Reillyc) Albert Einstein6. Which flying (movement) condition will always result in a Doppler speed of 0 m/s?a) Perfectly constant speed into/out of the antenna boresight b) Perfect concentric circle around antenna at constant altitude c) Speeds at integer multiples of antenna rotation rate 7. What does “MTI” stand for?a) Multiple Target Indicationb) Mean Time Intervalc) Moving Target Indication8. Synthetic Aperture Radar (SAR) radar is mostly likely to be located on which platform?a) Police carb) Shipc) Airplane9. Which feature of a “stealth” aircraft is most responsible for its low observability?a) Radar absorbent paintb) Multi-faceted surfacesc) Minimal use of metals in airframe10. What kind of radar did the webmaster of RF Cafe work on while in the U.S.A.F?a) MPN-14b) RDR-12c) NEXRADRF Quiz #8: Hallmark Decades in Electronics1. In which decade was the transistor invented? a) 1940sb) 1950sc) 1960s2. In which decade was the telegraph invented? a) 1810sb) 1840sc) 1870s3. In which decade was the Internet first implemented? a) 1950sb) 1960sc) 1970s4. In which decade was the first solid state integrated circuit demonstrated?a) 1950sb) 1960sc) 1970s5. In which decade were the first successful diode and triode vacuum tubes invented?a) 1880sb) 1890sc) 1900s6. In which decade was the telephone invented? a) 1850sb) 1860sc) 1870s7. In which decade was the AEEE (now the IEEE) founded? a) 1880sb) 1910sc) 1940s8. In which decade with the first transatlantic radio broadcast occur?a) 1880sb) 1890sc) 1900s9. In which decade was the SPICE simulator introduced? a) 1960sb) 1970sc) 1980s10. In which decade was the ARRL founded?a) 1910sb) 1920sc) 1930sRF Quiz #9: A Smorgasbord of RF Topics1. Where did Bluetooth? get its name?a) Nobody really knowsb) In honor of Harald Blåtand, once king of Denmark c) In honor ofits developer, “Big Blue” (IBM)d) From a Muppets characters by the same name2. Where did ZigBee get its name?a) Nobody really knowsb) From the zigzag path of a beec) Named after the comic strip character, Ziggyd) From the German phrase “sie gabe,“ meaning, “it just works” 3. Who is credited with conceiving of spread spectrum radio communications?a) Dr. Andrew Viterbib) Qualcommc) Actress Hedy Lamarrd) Kinch, the radio operator of Hogan’s Heroes4. What is meant by the front-to-back ratio of a Yagi antenna? a)The physical size of the front half of the antenna vs. the back half b) The number of driven elements vs. number of director elements c) Powerradiated in the front main lobe vs. power in opposite direction d) The weight proportion of the front half of the antenna vs. the back half 5. In an FM modulator with a 10 kHz deviation and a 5 kHz maximum modulating frequency,what is the total occupied bandwidth?a) 10 kHzb) 15 kHzc) 20 kHzd) 30 kHz6. Which WLAN standard provides the highest data rate? a)IEEE802.11a (5.1 GHz RF)54Mbpsb) IEEE802.11b (2.4 GHz RF)11Mbpsc) IEEE802.11g (2.4 GHz RF)54Mbpsd) IEEE802.11n (2.4 GHz RF)100Mbps+7. Why might the mounting orientation of a surface mount capacitor affect frequency response? a) The plates in the body could be either parallel to or perpendicular to the PCB, affectingcouplingb) Adhesion is usually better in one orientationc) Conductive epoxy adhesion is usually better in one orientationd) Orientation makes no difference8. If you were handed an unprocessed wafer of gallium arsenide (GaAs), silicon (Si), silicon-germanium (SiGe), and gallium nitride(GaN), how would you know which is GaN? a) GaN is transparent and the others are notb) The GaN wafer will be noticeably lighter in weightc) The GaN wafer will be much thinner than the othersd) It would not be possible to tell the difference9. The Smith Chart plot of a 50 ohm cable (in a 50 ohm system) spirals inward as theimpedance is plotted through multiple cycles. What is thatindicative of? a) A lossy cableb) A capacitive cablec) An inductive cabled) The cable is coiled on a spool10. What are the three primary JEDEC models used for ESD testing? a) High (HHM), Medium (MHM), and Low (LHM) Humidity Modelb) High (HVM), Medium (MVM), and Low (LVM) Voltage Modelc) Human Body (HBM), Machine (MM), and Charged Device (CDM) Model d) Heidi Klum, Claudia Schiffer, and Gisele BündchenRF Quiz #10: A Sampling of RF Topics 1. What format would a near-filed communications (13 MHz variety) antenna most likely take? a) Inductive coilb) Capacitive platec) Yagid) Parabolic dish2. What does SOLT stand for?a) Short Overload Testb) Simple OperationaL Testc) Short, Open, Load, Throughd) Strategic Offensive Limitation Talks3. Which instrument would be best to use to locate a defective waveguide joint? a) Microscopeb) Micrometerc) Spectrum Analyzerd) Time Domain Reflectometer4. Which entity in the U.S. determines whether an RF energy-emitting device is allowed to be operated?a) The Federal Communications Commissionb) The Amateur Radio Relay Leaguec) The Honor Systemd) The Underwriter’s Laboratory5. What does 2G, 2.5G, 3G, etc., mean in reference to cellphones? a) The average cost of service, expressed in thousands of dollars ($ grand) per yearb) The “generation” of the technologyc) It is an arbitrary alpha-numeric reference coded) The frequency band of operation, in GHz6. Where would you be likely to find a free wireless Internet connection? a) Hotel Lobbyb) Airportc) Your backyardd) All the above7. Who hosts the MTT-S International Microwave Symposium? a) Microwave Journal Magazineb) Microwaves & RF Magazinec) RF Design Magazined) The Institute of Electrical & Electronics Engineers8. What is the “rule of thumb” for estimating RF signal propagation distance vs. time in freespace?a) 1 millimeter per millisecondb) 1 meter per microsecondc) 1 foot per nanosecondd) 1 inch per picosecond9. What is the “rule of thumb” for estimating RF frequency vs. wavelength in free space?a) 300 MHz = 1 meterb) 100 MHz = 1 meterc) 300 MHz = 3 feet (1 yard)d) 100 MHz = 1 foot10. What is the most unique feature of a Helmholtz coil? a) The high voltage makes for cool Jacob’s Laddersb) Magnetic field lines are extremely uniform within the coil c) It is self-poweredd) It uses a rare earth element core1. Which "hand rule" applies for determining the direction of the magnetic field around acurrent-carrying wire? Assume conventional current flow from positive to negative, andmagnetic field leaving the north pole and entering the south pole.a) Right-hand ruleb) Left-hand rulec) Whole-hand rule2. What is the name given to the displaypattern when independent signals are fedinto the x-axis and y-axis ports of anoscilloscope?a) X-Y waveformb) Lissajous waveformc) Complex3. How is the word "Fresnel" pronounced (as in Fresnel zone or Fresnel grating)?a) frēs-n?l'b) frā-n?l'c) fr?s-n?l'4. What type of filter is shown to the right?a) Lowpassb) Highpassc) Bandpass5. What is the order of the filter shown to the right?a) 2b) 4c) 66. What type of transmission line is shown to the right?a) Coaxialb) Striplinec) Microstrip7. What type of waveguide bend is shown to the right?a) 90? Maxwell bendb) 90? H-Plane bendc) 90? E-Plane bend8. What is the value of the resistor shown on to the right?a) 6.2 kΩ, ?5%b) 62 kΩ, ?5%c) 62 kΩ, ?10%9. What serious problem is commonly caused with lead-free, tin-alloy soldersa) Tin whiskersb) Cold flowingc) Spontaneous combustionRF Quiz141. Who from this list is usually credited with being the first to experiment with high frequencyoscillator circuits?a) Benjamin Franklinb) Nikola Teslac) Edwin Armstrongd) Albert Einstein2. In the four basic oscillator circuits shown below, what is the primaryfunction of the transistor?a) Frequency controlb) Amplitude controlc) Compensation for tank circuit lossesd) Isolation3. Which type of oscillator circuit is shown to the right?a) Colpitts oscillatorb) Clapp oscillatorc) Hartley oscillatord) Pierce oscillator4. Which type of oscillator circuit is shown to the right?a) Colpitts oscillatorb) Clapp oscillatorc) Hartley oscillatord) Pierce oscillator5. Which type of oscillator circuit is shown to the right?a) Colpitts oscillatorb) Clapp oscillatorc) Hartley oscillatord) Pierce oscillator6. Which type of oscillator circuit is shown to the right?a) Colpitts oscillatorb) Clapp oscillatorc) Hartley oscillatord) Pierce oscillator7. Which factor is most important in maintaining spectral purity in an oscillator circuit?a) Overall circuit Q (quality factor)b) Component sizesc) Q of individual componentsd) Transistor gain8. What does the term "frequency pulling" refer to?a) Change in frequency due to power supply variationsb) Change in frequency due to load variationsc) Change in frequency due to thermal variationd) All the above9. In a phase-locked loop (PLL) oscillator circuit, what does the phase detector do?a) Detects phaseb) Compares relative phase between the reference input andoscillator output and introducesa shift as necessary to maintain phase coherencec) Injects random phase shifts at the input to stabilize the output frequency d) Phase detectors are not used in PLL circuits10. Complete the following adage used in the days before computer simulators. "If you want anoscillator, design an amplifier. If you want an amplifier, design a(n) ____."a) Amplifierb) Filterc) Oscillatord) RadioRF Quiz15231. To which constant is 6.022*10/ mol assigned?a) universal constantb) Avogadro's constantc) electric fieldd) gravitational constant2. To which constant is 2.718 assigned?a) base of natural logarithmsb) base of unnatural logarithmsc) ratio of major and semi-major axis of an ellipse d) dielectric constant of ceramic3. To which constant is 9,192,631,770 assigned?a) astronomical unitb) oscillations of a cesium atom in exactly one second c) picoangstroms in a meterd) hours in a lightyear-354. To which constant is 1.616*10 m assigned?a) Planck lengthb) thickness of a human hairc) wavelength of yellow lightd) tolerance of the standard meter-285. To which constant is 9.11*10 g assigned?a) neutron rest massb) proton accelerationc) electron rest massd) photon acceleration6. To which constant is 9.81 m/s? assigned?a) speed of light in a vacuumb) dielectric constant of a vacuumc) acceleration of gravity near Earth's surface d) magnetic constant-127. To which constant is 8.854*10 F/m assigned?a) rate of change of temperature in silicon b) speed of light in a vacuumc) permittivity of free spaced) permeability of free space88. To which constant is 2.998*10 km/s assigned to?a) orbital velocityb) electron speedc) acceleration of gravityd) speed of light in a vacuum-239. To which constant is 1.3807*10 J/K assigned?a) universal gas constantb) carbon band energyc) uranium band energyd) Boltzmann's constant-610. To which constant is 1.257*10 H/m assigned?a) Bohr radiusb) speed of light in a vacuumc) permittivity of free spaced) permeability of free spaceRF Quiz161. What does dBi, the most often used unit for antenna gain (or directivity), stand for?a) Decibels of isolationb) Isometric radiation in decibelsc) Decibels of gain relative to an isotropic radiator d) Intrinsic gain in decibels2. For which region of space does antenna gain normally apply?a) Near fieldb) Far fieldc) At the feed pointd) EverywhereElevation Pattern Azimuth Pattern3.For which type of antenna does the pattern to the right describe?a) Parabolicb) Yagic) 1/2-wave dipoled) 1/4-wave vertical whip4. What is the free space impedance that an antenna "sees?"a) 50 Ωb) 75 Ωc) 16p Ω (?50 Ω)d) 120p Ω (?377 Ω)5. What is the name given to the point where the RF input signal interfaces to the antenna?a) ICP (input connection point)b) Feed-pointc) BNC connectord) N connector6. Where is the approximate transition point between near field and far field?a) λ / (2p)b) λc) 5λd) 10λ7. What is an isotropic radiator?a) An antenna that radiates equally in all directions b) An antenna with equal dimensionsc) An antenna designed to broadcast in the troposphere d) None of the above8. Which type of antenna would typically have the highest directivity?a) 1/4-wave whipb) Folded dipolec) Yagid) Parabolic9. On a center-fed 1/2-wave dipole, where is the voltage potential the highest?a) In the centerb) At the tipsc) Equal everywhered) Nowhere - dipoles operate on current10. Yagi antennas are constructed of which three types of elements?a) Transmitter, receiver, and transceiverb) Underdriven, driven, and overdrivenc) Reflector, driven, and directord) Aluminum, iron, and magnesiumRF Quiz171. Who is credited with inventing the computer mouse?a) Bill Gatesb) Steve Jobsc) Bill Nye (the science guy)d) Douglas Engelbart2. Who is credited with discovering the transistor?a) John Bardeenb) William Shockleyc) Walter Brattaind) All the above3. Who invented the Viterbi programming algorithm?a) Andrew Viterbib) Robert Peasec) Albert Einsteind) Robert Lucky4. Who is credited with inventing the triode amplifier vacuum tube (Audion)?a) Sir Jonathan Audionb) James Wattc) Brian Koenigsmarkd) Lee De Forest5. Who invented the tunnel diode?a) Scott Adamsb) Leo Esakic) Patrick Fitzgeraldd) Igor Stravinsky6. Who is credited with inventing spread spectrum communications?a) Akio Moritab) Thomas Steenlandc) Hedy Lamarrd) Albert Gore7. Who is credited with inventing frequency modulation (FM)?a) Edwin Armstrongb) Heike Onnesc) Robert Jarvikd) Charlie Eppes8. Who is credited with inventing television?a) Yataro Iwasakib) Lothar Rohdec) Hermann Schwarzd) Philo Farnsworth9. Who is credited with inventing radar?a) Gordon Gouldb) Elmer Sperryc) Sir Robert Watson-Wattd) Augustus Raytheon10. Who is credited with inventing the first integrated circuit?a) Garrett Morganb) Jack Kilbyc) James (Jim) Wilsond) Grace HopperRF Quiz18. Gutta perchaa) 16th century Indian physicist b) Latin for "cat gut," used for stringed instrumentsc) Cable insulationd) Explosive compound2. Condensera) Capacitorb) Air pumpc) Mass compactord) Electrical probe3. Luminiferous aethera) Flame created by laboratory heatersb) Medium that supports the transmission oflight particlesc) The "light of the moon" d) Glowing gas4. Thermionic valvea) Vacuum tube diodeb) Heat flow switchc) Systolic pumpd) Lock5. Dephlogisticated aira) Dry (dehumidified) air b) Perfect vacuumc) Supersaturated aird) Molecular oxygen6. Corpusclea) Low-ranking enlisted man's bicepb) Free radicalc) Electrond) Light particle7. Audiona) Music aficionadob) Sound generatorc) Vacuum tube trioded) Sound level meter8. Calorica) A stomach settling medical remedyb) Unit of workc) Unit of electrical resistance d) Fluid responsible for heat flow9. Leyden jar。

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