射频工程师常见面试题

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射频面试知识点总结

射频面试知识点总结
一、电磁波基础知识
1. 电磁波的基本特性
2. 电磁波的传播方式
3. 电磁波的频率和波长的关系
4. 电磁波在空间中的传播特性
5. 电磁波在不同介质中的传播特性
二、射频电路基础知识
1. 电感和电容的基本特性
2. 能量在电感和电容中的储存和释放方式
3. 电感和电容在射频电路中的应用
4. 射频电路中的谐振和频率选择
5. 射频电路中的阻抗匹配和功率传输
三、射频器件和元器件
1. 射频二极管的工作原理和特性
2. 射频放大器的工作原理和分类
3. 射频滤波器的原理和应用
4. 射频天线的构造和工作原理
5. 射频混频器的工作原理和应用
四、射频系统设计
1. 射频信号调制和解调技术
2. 射频系统中的噪声和干扰处理
3. 射频系统中的射频功率控制技术
4. 射频系统中的频率合成和频率转换技术
5. 射频系统中的信号检测和解调技术
五、射频测试技术
1. 射频信号的调制和解调
2. 射频信号的频率合成和频率转换
3. 射频信号的功率测量和功率控制
4. 射频信号的频谱分析和频谱测量
5. 射频信号的噪声和干扰测试
以上是射频技术面试中的一些基础知识点，希望能对您有所帮助。

射频工程师认证证书考试

射频工程师认证证书考试一、填空题（每空1分，共20分）自由空间的阻抗为______Ω。

答案：377射频工程师在设计系统时，需考虑接收机的噪声系数。

当在接收机输入端加入一个10 dB衰减器时，噪声系数______。

答案：不变（或详细解释：噪声系数不随输入衰减器的加入而改变）一个RF系统具有+10 dB的线性吞吐量增益和+30 dBm的输出三阶截断点（OIP3）。

其输入三阶截断点（IIP3）为______dBm。

答案：+20（根据增益公式计算得出）在给定的阶数（如N=5）下，具有最大选择性的滤波器类型是______。

答案：Chebychev（ripple=0.1 dB）在射频混合器中，一个5阶的杂散产物是______。

答案：6LO - 1RF（或其他正确选项，根据具体题目选项确定）一个2.8 GHz的振荡器相位锁定到一个10 MHz的参考振荡器，后者在1 kHz偏移处的单边相位噪声为-100 dBc。

则2.8 GHz振荡器在1 kHz偏移处的单边相位噪声为______dBc。

答案：需具体计算，但一般涉及频率转换和噪声增加的计算（如-51.1 dBc，视具体计算方法而定）介电常数为4.6的PCB板传输1.4 GHz信号时，该PCB板上信号的最接近波长可通过公式计算得出，结果需根据实际情况给出。

Smith圆图中，点位于下半部分代表______。

答案：电容性阻抗Smith圆图中心水平线最左端点的阻抗为______。

答案：无限大（开路）QPSK、8-PSK、16-PSK的误码率大小比较，通常随着调制阶数的增加，误码率______。

答案：增加（但具体数值需根据实际环境和系统参数确定）二、单项选择题（每题2分，共20分）在移动通信传播环境中，快衰落损耗遵从______。

A. 瑞利分布B. 高斯分布C. 均匀分布D. 泊松分布答案：A下列哪个参数常用于表示天线相对于全向天线的增益？A. dBdB. dBmC. dBcD. dBi答案：D一个理想的12位模数转换器（ADC）的动态范围是多少dB？（假设满量程为1Vpp）A. 60 dBB. 72 dBC. 84 dBD. 96 dB答案：B（计算方式为：20*log10(2^12/2) ≈72 dB）在天线方向图中，前后瓣最大电平之比称为前后比，其典型值为______dB。

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。

中兴通讯招聘面试试题及过程

中兴通讯招聘面试试题及过程算法工程师面试经历(南京) - 南京中兴通讯面试过程：面试一共分为两轮面试，一轮技术面，还有一轮终面。

技术面完毕后，等了10分钟左右就去终面了。

面试是在一个大房间进展的，里面是很多个面试小组，两个面试官和一个被面试人员。

最开场先是一个自我介绍，然后面试官会问你会哪一种编程语言，然后根据编程语言，问了我一些根底的问题。

后来问我通信原理中印象最深化的是哪一个局部的内容。

后来就是终面，聊了一下兴趣爱好，比拟随意，最后问我有没有问题要问他们。

面试官问的面试题：面试就是根据你会的内容来提问，还算是比拟根底的问题，问的再多了我也不会了。

这是我第一次面试，当时很不自信，自我介绍的时候都卡住了，后来略微好一点，虽然没通过，不过算是锻炼一下自己的面试才能吧。

软件开发工程师面试经历(西安) - 中兴通讯股份面试过程：一面是两个面试官，先自我介绍，然后问我专业知识技能，C语言C++，数据库，操作系统，计算机网络，数据构造，设计形式。

一面完毕后让我在外面等待，过了10分钟后进展二面，也是2个面试官，同样自我介绍，然后问一些非专业问题。

比方是否愿意加班出差，出国。

工作中遇到不会的问题怎么办，家庭背景。

意向城市等等。

面试官问的面试题：1.C语言和C++的区别2.继承，重载，多态。

3. 说一下快速排序原理和复杂度。

常用排序算法。

4. TCP和UDP的区别5. 网络七层模型6.数据库分组语句7. 操作系统进程有几种状态。

8. 功能测试9. 设计形式10. 数据构造二叉树最短途径11. 迪杰斯特拉算法。

电源研发岗面试经历(武汉) - 中兴通讯面试过程：面试的气氛很轻松，所以小伙伴们不要太紧张，保持自信的状态就行了。

首先进去让我很意外的是面试官没有让我进展自我介绍，在核实了学生证和四六级证书之后就直接进入问问题环节，首先问的是简历上的工程，本人研究生阶段做过3个工程，工程都问到了。

然后就开场问专业知识，软件硬件的都有，建议最好确定到底是要找电源软件编写和硬件设计的，不然他会两个都问，说实话有点吃不消。

射频面试基础知识

射频面试基础知识1. 介绍在射频领域的面试中，了解和掌握一些基础知识是非常重要的。

本文将为您介绍一些射频面试中常见的基础知识，帮助您更好地准备和应对射频面试。

2. 射频概述射频（Radio Frequency）是指在无线通信中使用的频率范围，通常指300 MHz 至300 GHz的电磁波频率范围。

射频技术在无线通信、雷达、卫星通信等领域广泛应用。

3. 射频信号特性射频信号具有以下特性：•频率：射频信号的频率通常是以Hz为单位进行表示。

常见的射频信号频率范围包括LF（低频）、HF（高频）、VHF（甚高频）、UHF（超高频）等。

•波长：射频信号的波长是指在空间中一周期的长度。

波长与频率之间有固定的关系，可以通过公式λ = c/f 计算，其中λ为波长，c为光速，f为频率。

•功率：射频信号的功率用dBm（分贝毫瓦）或者W（瓦）表示。

dBm是一种相对功率单位，常用于表示射频信号的强度。

•调制方式：射频信号可以通过调制方式来携带信息。

常见的调制方式包括调幅（AM）、调频（FM）、调相（PM）等。

4. 射频器件射频系统中常用的器件包括：•天线：天线是将电磁波转换为电信号或者将电信号转换为电磁波的装置。

天线的类型包括定向天线、全向天线、扁平天线等。

•滤波器：滤波器用于在射频信号中选择特定的频率范围，同时滤除其他频率的信号。

常用的滤波器包括带通滤波器、带阻滤波器等。

•放大器：放大器用于增加射频信号的功率。

常见的放大器包括功率放大器、低噪声放大器等。

•混频器：混频器用于将两个不同频率的信号进行混合，得到新的频率信号。

常见的混频器有单、双、三、四端口混频器等。

5. 射频传输线射频传输线用于在射频系统中传输信号。

常见的射频传输线包括同轴电缆、微带线、矩形波导等。

不同的传输线具有不同的特性阻抗和损耗。

•同轴电缆：同轴电缆由内导体、绝缘体和外导体组成。

它具有较低的传输损耗和较高的抗干扰能力，适用于高频信号的传输。

•微带线：微带线是一种将导线印刷在介质板上的传输线。

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。

射频面试基本知识

射频面试基本知识1. 介绍射频（Radio Frequency，简称RF）是指无线电波在无线通信中的传输媒介。

在现代无线通信系统中，射频技术扮演着至关重要的角色。

射频面试基本知识是面试时经常涉及的一个重要部分，掌握这些知识对于从事射频工程相关职位的求职者来说至关重要。

本文将介绍射频面试中常见的一些基本知识点，帮助读者更好地准备面试，提升自己在射频领域的竞争力。

2. 射频频段射频频段是指无线电波的频率范围。

在无线通信中，不同的应用会使用不同的频段。

以下是一些常见的射频频段：•低频（LF）：30 kHz - 300 kHz•中频（MF）：300 kHz - 3 MHz•高频（HF）：3 MHz - 30 MHz•甚高频（VHF）：30 MHz - 300 MHz•超高频（UHF）：300 MHz - 3 GHz•极高频（SHF）：3 GHz - 30 GHz•特高频（EHF）：30 GHz - 300 GHz在不同的频段中，射频信号的特性和传播方式也会有所不同。

在射频面试中，面试官可能会问到某个频段的特点及其在通信系统中的应用。

3. 射频器件射频器件是指在射频电路中起关键作用的元器件。

以下是一些常见的射频器件：•滤波器：用于在射频电路中滤除不需要的频率成分。

•放大器：用于放大射频信号的幅度。

•混频器：用于将射频信号与本地振荡器产生的信号进行混频，得到中频信号。

•变频器：用于将射频信号的频率转换到其他频段。

•发射器和接收器：用于无线通信系统中的信号发射和接收。

在射频面试中，可能会涉及到这些射频器件的工作原理、性能参数以及选型等方面的问题。

4. 射频传输线射频传输线是指在射频电路中用于传输射频信号的导线或导轨。

常见的射频传输线有以下几种：•同轴电缆：由内导体、绝缘层、外导体和外护套组成，适用于高频和宽带信号的传输。

•微带线：由金属线和绝缘基板组成，适用于高频和微波信号的传输。

•波导：由金属管道或金属壳体组成，适用于超高频和毫米波信号的传输。

射频工程师常见面试题

1. 你做过什么项目？画出原理图，讲述各个器件的意义，描述信号的传输等等。

（这个基本每家单位都会问）2. 画出二端口网络S 矩阵框图，并说明每个参数的意义。

3. dBi与dBd什么区别？dB与dBm什么关系，dBm与电压怎么换算的？4. 画出smith 圆图，指出开路点、短路点、匹配点，并说明阻抗原图与导纳圆图的关系。

5. 一个负载阻抗并联一个电感或电容，怎么在smith 圆图求出其输入阻抗？6. 微带线特性阻抗与哪些因素有关？与线长L 有关吗？7. 写出传输线输入阻抗的表达式，并说明同一传输线上不同两点反射系数的关系。

8•请画出3dB威尔金森功分器原理图。

9•请写出单级放大器噪声系数的表达式，多级放大器级联NF又如何？10. 放大器的增益有哪几种？有什么区别和联系？11. 放大器绝对稳定的条件是什么？请写出表达式。

12. 请问低噪声放大器输入端和输出端匹配原则是什么？阻抗匹配的目的是什么？13. 低噪声放大器中高频扼流圈的作用是什么？14. 低噪声放大器的主要性能指标有哪些？15. 功率放大器的1dB压缩点怎么定义的？IIP3又是指什么？有何意义？16. 功率放大器有哪几种工作状态？各有什么区别？17. 请画出一般接收机的系统框图，并说明各个模块的用处。

18. 天线的性能指标有哪些？19. 天线的极化方式有哪些？请画出半波对称阵子的方向图。

20. 你会使用的微波软件有哪些？测量仪器有哪些？熟练程度如何？小结：以上差不多就是我面试遇到所有有关射频微波方面的问题，其实总体看上去难度不大，但很注重基础，范围很广，问的也很细，所以要想全部回答上来，还需下一番功夫，认真得把基础打好，再学学软件多动动手，加深对概念和原理的认识。

从实践中学习，再回到书本好好理解和品味我认为是很重要的。

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！。

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。

研发中心第一研究室射频工程师岗位考评试题(部分答案)

研发中心第一研究室射频工程师岗位考评试题姓名：姓名：考试日期：成绩：一、填空题1.三极管放大电路的三种基本组态是共基、共射、共集。

2.在甲类、乙类和甲乙类功率放大电路中，效率最低的电路为甲类3. 波长λ、频率f和速度v的关系是λ=V/F ；4.表述天线增益单位有 dBi 和 dBd5.通信系统按信号复用方式分类，分为：时分复用、频分复用、码分复用大器后，信号噪声比变坏的程度9.目前移动通信应用的双工方式有 TDD 和 FDD16.移动通信系统中的多址方式有三种，分别是 TDMA ， FDMA 和 CDMA 。

GSM系统，品牌是 Prewell28.1W= 1000 mW= 30 dBm29. 0.0001 W= -10dBm； 0.001 W =0dBm； 0.01 W =10dBm；30.5W= 37 dBm； 10W = 40 dBm； 20W = 43 dBm；31.表述直放站输出功率单位有瓦和dBm ；表述直放站下行增益的单位有倍和36. 使用仪器仪表进行设备调试中，应采取全面防护手段，列举5项措施穿静电衣，静电鞋，带静电手环，加隔直器，隔离器，还有衰减器，接地线37. 3G的含义是38.一般使用的39.移动通信系统的特性阻抗为50 欧姆二、不定项选择题1.三极管工作于放大状态的条件是（ B ）A.发射结正偏，集电结反偏B.发射结正偏，集电结正偏C.发射结反偏，集电结正偏D.发射结反偏，集电结反偏2.甲乙类功放电路功放三极管的导通角θ为( B )。

A.θ=2πB.π﹤θ﹤2πC.θ=π3.电压驻波比的简写是（A ）A.VSWRB.VWSRC.VRSWD.WRVS4.下列不含有ALC功能的模块有（）A.功放B.低噪放C.移频器D.选带器5.二功分的实现方式包括（）A.3dB电桥B.微带二功分器C.电阻搭接6.在给模块拧螺丝的时候应遵循的原则是（ABC）A.交叉B.对称C.逐步7.测试互调指标必备的仪器有（BC）A.单音信号源1台B.双音信号源1台C.频谱仪1台8.测试功放输出驻波比必备的仪器及工具有（AC）A.网络分析仪B.频谱仪C.双定向耦合器D.隔离器9.测量功放的输出功率的仪器有（ABC）A.频谱仪B.功率计C.网络分析仪D.噪声仪10.ALC指标是控制模块的（B）A.增益B.输出功率C.输入功率三、简答题1.请解释几个电磁换算单位：dBm,dB,dBc2.关于smith图的相关知识。

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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