射频工程师笔试题

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射频工程师笔试题

射频工程师笔试题一、选择题1、下列哪一种电磁波的频率最高？A.无线电波B.红外线C.紫外线D. X射线答案：D. X射线。

X射线的频率最高，其波长在0.01-10纳米之间，具有很强的穿透能力和很高的能量。

无线电波、红外线和紫外线的频率都比X射线低。

2、下列哪一种设备可以用来产生射频信号？A.示波器B.信号发生器C.频谱分析仪D.功率放大器答案：B.信号发生器。

信号发生器可以产生各种频率的信号，包括射频信号。

示波器用于显示波形；频谱分析仪用于分析信号的频率成分；功率放大器用于放大信号的功率。

3、在射频电路中，下列哪一种元件通常用来实现信号的放大？A.电阻B.电容C.三极管D.二极管答案：C.三极管。

三极管是一种常用的射频放大器，它可以通过控制基极电流来控制集电极电流，从而实现信号的放大。

电阻、电容和二极管通常不是用来实现信号放大的元件。

二、简答题4、简述射频工程师的工作内容是什么？答案：射频工程师的主要工作内容包括设计、开发和测试射频电路和系统。

他们需要具备对射频信号和系统的深入理解，包括信号的发射、接收、传播和干扰等方面的知识。

射频工程师还需要了解各种射频元件的工作原理和特性，以及掌握相关的测试和调试技术。

在实际工作中，射频工程师还需要与其他工程师密切合作，以确保整个系统的性能和稳定性。

41、简述射频工程师需要具备哪些技能和知识？答案：射频工程师需要具备以下技能和知识：（1）掌握射频电路和系统的基础理论和设计方法；（2）熟悉各种射频元件的工作原理和特性，包括放大器、滤波器、天线、调制器等；（3）掌握射频测试和调试技术，包括频谱分析、网络分析、噪声测试等；（4）了解相关的行业标准和规范，如ISO、ETSI等；（5）具备较好的电子电路设计和调试能力；（6）熟悉常用的电子测量仪器和工具，如示波器、频谱分析仪、矢量网络分析仪等。

体系工程师笔试题目一、选择题1、下列哪一项不是体系工程师的职责？A.制定质量管理体系标准B.审核质量管理体系文件C.管理质量管理体系的运作D.招募体系工程师2、在质量管理体系中，下列哪一项描述错误？A.所有的过程都需要被分析和控制B.客户满意度是评估质量管理体系的一个重要指标C.所有的产品都需要进行特性值检测D.持续改进是质量管理体系的一个重要原则3、如果一个公司在产品开发阶段就发现了问题，下列哪一项措施最合适？A.重新设计产品B.对问题进行根本原因分析，并采取措施进行纠正和预防C.对产品进行更加严格的检测D.对员工进行再培训，以避免问题再次发生4、下列哪一项措施可以帮助提高一个公司的质量管理水平？A.增加员工数量B.提高员工素质和技能水平C.扩大公司的生产规模D.提高公司的资金实力二、简答题1、请简述体系工程师在质量管理体系中的作用。

射频工程师笔试题目

微博人才网1.一个威尔金森功分器，从2和3端口分别输入两个频率分别为f1,f2的信号，且幅度均为0dBm,请问1端口输出为什么信号，幅度多大？（我写的答案是输出为二者的和，通过和差化积公式，变成一个调幅波，不知道对不对？？2.6dB派型电阻衰减器，请写出R1,R2,R3三个电阻的详细计算过程，精确到个位。

（没找到哪本书上有讲如何推导的啊，有没有推荐的教材，我要研究一下，网上有现成的计算公式，这哪记得住啊）3.某型号频谱仪低噪为-165dBm/Hz，当RBW设为100KHz时，能否区分出幅度为-120dBm左右的单音信号？如希望准确测量此单音信号的幅度，同时希望尽量节约测试时间，RBW应如何设置？（什么是RBW都不知道，囧）4.请解释什么是AB类放大器，为什么CDMA末级功放采用这种类型的？（我就说导通角介于360-180之间，线性工作，但效率又比A类的高，综合考量线性度和效率，选用AB 类，不知道是不是答非所问啊）5.如图所示，请问图示两个电路各实现什么功能问题1：要看2个输入信号的相位。

问题2：这个，我只能说出大概思路，要我现场手算，搞不好要1个小时，只知道3个电阻分别是150欧姆，150欧姆，36欧姆。

问题3：测不出，如果需要测量，将rbw打成10k问题4：你回答的基本正确问题5：第一个用作可调衰减器，第二个用作移相器关于RBW和VBW的解释，网上可以找到一些，但是总感觉解释的不是很清楚。

我所说的只能算是一个参考吧，个人的理解。

希望能以此抛砖引玉，得到更满意的解释。

RBW称为分析带宽，就是频谱仪当中下变频以后的中频带宽。

它决定了FFT变换的二进制长度。

RBW与采样点数成反比。

一般来说，比较小的RBW有更好的分辨率，就是能正确的分辨处两个信号。

一般来说我们都有这样的经验。

当输入两个频率很近的信号，如果SPAN打的比较大的话，两个信号就会混迭在一起。

这是因为如果不是专门的设定RBW。

一般RBW会随SPAN自动调节。

射频和数字电路笔试题目

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?2. NF 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。

3. IP3 IP3 的定义。

级联IP3 公式。

IP3 测试设备连接框图和测试方法。

IP3 和IM3 的关系公式。

4. P1dB P1dB 的定义。

P1dB 的测试方法。

5. 电阻PI（衰减器）给出不同衰减值对应的电阻值。

已知衰减值（AdB）和源&负载阻抗（50 Ohm），请给出电阻值计算方法。

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。

7. 电容类型、值系列、使用时哪些指标需要降额使用、等效电路。

8. 电感类型、值系列、使用时主要考虑哪些指标、等效电路。

贴片电感的主要供应商。

SRF 的含义，不同电感值的SRF 频率。

9. 射频器件：射频放大器、Mixer、滤波器、衰减器、3dB 桥、隔离器、耦合器、合/分路器、PLL Module、VCO。

主要供应商，每类器件的主要指标，使用过的品牌和型号和指标。

射频放大器的原理图（包括外围电路），外围电路如何取值。

10. 射频接收通路系统指标：接收机灵敏度、接收机动态范围等、抗干扰性能。

接收机灵敏度、接收机动态范围等、抗干扰性能的定义。

你所熟悉的系统的接收机灵敏度公式、接收机灵敏度的值。

你所熟悉的系统的抗干扰性能如何实现。

11. 射频发射通道系统指标：发射功率、杂散要求、信号质量要求。

12. 你所熟悉的系统的发射功率、杂散要求、信号质量要求。

13. 原理图经验工具软件，网络数，如何检查原理图的正确性，原理图库是否自己做的。

14. PCB 设计经验PCB 外形尺寸、PCB 厚度、线特征阻抗、线特征阻抗是否和频率相关，使用什么工具计算特征阻抗。

15. 高速数字信号完整性源端/负载端匹配的原理和PCB 上的实现。

降低串扰的要求。

射频工程师笔试试题

1 请简述锁相环的基本构成与工作原理，各主要部件的作用。

答：相环由以下三个基本部件组成：鉴相器（PD）、环路滤波器（LPF）和压控振荡器（VCO）。

锁相环的工作原理： 1. 压控振荡器的输出经过采集并分频； 2. 和基准信号同时输入鉴相器； 3. 鉴相器通过比较上述两个信号的频率差，然后输出一个直流脉冲电压； 4. 控制VCO，使它的频率改变； 5. 这样经过一个很短的时间，VCO 的输出就会稳定于某一期望值。

锁相环可用来实现输出和输入两个信号之间的相位同步。

当没有基准（参考）输入信号时，环路滤波器的输出为零（或为某一固定值）。

这时，压控振荡器按其固有频率fv进行自由振荡。

当有频率为fr的参考信号输入时，Ur 和Uv同时加到鉴相器进行鉴相。

如果fr和fv 相差不大，鉴相器对Ur 和Uv进行鉴相的结果，输出一个与Ur 和Uv的相位差成正比的误差电压Ud，再经过环路滤波器滤去Ud中的高频成分，输出一个控制电压Uc，Uc将使压控振荡器的频率fv（和相位）发生变化，朝着参考输入信号的频率靠拢，最后使fv= fr，环路锁定。

环路一旦进入锁定状态后，压控振荡器的输出信号与环路的输入信号（参考信号）之间只有一个固定的稳态相位差，而没有频差存在。

这时我们就称环路已被锁定。

⑴鉴相环(或相位比较器,记为PD或PC)：是完成相位比较的单元，用来比较输入信号和基准信号的之间的相位。

它的输出电压正比于两个输入信号之相位差。

⑵低通滤波器(LPF)：是个线性电路，其作用是滤除鉴相器输出电压中的高频分量，起平滑滤波的作用。

通常由电阻、电容或电感等组成，有时也包含运算放大器。

⑶压控振荡器（VCO）：振荡频率受控制电压控制的振荡器，而振荡频率与控制电压之间成线性关系。

在PLL（锁相环）中，压控振荡器实际上是把控制电压转换为相位。

2 请说出产生线性调频信号的几种方法。

2答：LFM的产生方法很多, 如采用SAW器件的无源法，采用VCO器件的有源法等等。

射频工程师招聘笔试题与参考答案(某大型央企)2024年

2024年招聘射频工程师笔试题与参考答案(某大型央企)(答案在后面)一、单项选择题（本大题有10小题，每小题2分，共20分）1、射频工程师在进行天线设计时，以下哪种因素对天线的增益影响最大？A、天线尺寸B、天线材料C、天线形状D、天线谐振频率2、在射频电路中，用于实现信号放大功能的器件是？A、二极管B、三极管C、晶振D、电阻3、射频工程师在进行天线设计时，以下哪个参数是决定天线方向图形状的关键因素？（）A. 天线增益B. 天线带宽C. 天线极化方式D. 天线口径4、在射频电路设计中，以下哪种元件在实现阻抗匹配中最为常用？（）A. 变容二极管B. 变阻二极管C. 谐振腔D. 微带线5、射频工程师在调试一个2.4GHz的无线通信系统时，需要检测信号强度。

以下哪个工具最适合用于测量2.4GHz频段的信号强度？A. 示波器B. 网络分析仪C. 频谱分析仪D. 数字万用表6、在射频设计中，以下哪个概念与信号在传输过程中的衰减有关？A. 增益B. 反射C. 折射D. 衰减7、射频工程师在调试天线系统时，以下哪一项不是衡量天线性能的主要参数？A. 频率范围B. 增益C. 噪声系数D. 频率响应8、在射频系统中，以下哪一项不是导致信号失真的原因？A. 天线阻抗不匹配B. 射频电缆损耗C. 模拟信号滤波器设计不当D. 数字信号处理算法错误9、射频工程师在进行无线通信系统设计时，以下哪个参数对系统的带宽影响最大？A. 信号频率B. 信号功率C. 信号调制方式D. 信号带宽 10、在射频电路设计中，以下哪种技术可以有效地抑制电路中的噪声干扰？A. 加密技术B. 数字滤波技术C. 增加电路元件的精度D. 降低电路的工作电压二、多项选择题（本大题有10小题，每小题4分，共40分）1、射频工程师在进行天线设计时，以下哪些因素会影响天线的增益？（）A、天线尺寸B、天线形状C、天线材料D、工作频率E、馈电方式2、在射频电路设计中，以下哪些元件或技术可以实现信号的匹配？（）A、匹配网络B、可调电阻C、滤波器D、衰减器E、共模扼流圈3、射频工程师在设计和优化无线通信系统时，以下哪些因素会影响系统的性能？（）A、发射功率B、天线增益C、频率带宽D、信道编码方式E、调制方式4、在以下哪些情况下，射频工程师需要进行天线阵列设计？（）A、需要提高信号的定向性B、需要扩大信号覆盖范围C、需要降低信号的干扰D、需要提高信号的抗干扰能力E、需要实现信号的波束赋形5、射频工程师在进行天线设计时，以下哪些因素会影响天线的增益？（）A. 天线的尺寸B. 天线的形状C. 天线的材料D. 天线的辐射方向图E. 天线的表面处理6、在射频系统设计中，以下哪些技术可以用来提高系统的抗干扰能力？（）A. 使用滤波器B. 增加发射功率C. 采用频率跳变D. 使用差分信号传输E. 提高系统带宽7、射频工程师在进行天线设计时，以下哪些因素会影响天线的增益？（）A. 天线的形状B. 天线的尺寸C. 天线的材料D. 天线的工作频率E. 天线的阻抗匹配8、在射频电路设计中，以下哪些技术可以用于减少信号干扰？（）A. 使用低噪声放大器B. 采用差分信号传输C. 使用屏蔽电缆D. 采用滤波器E. 提高电路的电源质量9、射频工程师在设计和调试无线通信系统时，以下哪些因素会影响系统的性能？A. 天线增益B. 发射功率C. 信道带宽D. 信号调制方式E. 信号传播损耗 10、在射频电路设计中，以下哪些方法可以用于降低噪声干扰？（）A. 使用低噪声放大器（LNA）B. 选择合适的滤波器C. 采用差分信号传输D. 使用屏蔽材料E. 优化PCB布局三、判断题（本大题有10小题，每小题2分，共20分）1、射频工程师在进行电路设计时，必须保证所有的射频元件都工作在它们的标称频率范围内。

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。

射频工程师笔试题——附答案

一、填空题（每题5分，10题，共50分）1.功率1W = 30dBm。

2.贴片电阻上的103代表10K欧姆阻值。

3.三极管在工作时，发射结和集电结均处于正向偏置，该晶体管工作在饱和状态。

4.假设A传输线的特征阻抗是70欧姆，B传输线的特征阻抗是30欧姆，A传输线与B传输线相连，那么它们之间的反射系数是0.4 。

（-0.4也可以是正确答案）5.Smith阻抗圆图的最左侧点对应的是短路，阻抗圆图的最右侧点对应的是开路。

6.负载阻抗串联一个电感，则输入阻抗在Smith圆图上如何变化？以负载阻抗点为起点，围绕等阻抗圆顺时针旋转。

7.负载阻抗为Z L，经过阻抗为Z0，长度为λ/4的传输线，则阻抗变为Z02/Z L。

8.请写出级联网络的噪声系数计算公式NF TOTAL = NF1+ (NF2-1)/G1+ (NF3-1)/G2 + …+(NF n-1)/G n-1 。

10.请写出接收机的灵敏度计算公式P IN MIN = -174dBm/Hz + 10log(B) + NF + SNR OUT MIN ，使用B表示符号速率，NF表示噪声系数，SNR OUT MIN表示解调门限。

随着输入功率的继续增加，放大器进入非线性区，其输出功率不再随输入功率的增加而线性增加，也就是说，其输出功率低于小信号增益所预计的值。

通常把增益下降到比线性增益低1dB时的输出功率值定义为输出功率的1dB 压缩点，用P1dB表示。

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）。

射频基础考试题（答案）

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。

射频基础二级工程师考试题及答案

射频基础二级工程师考试题及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．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33 dBm，基站输出功率46dBm为40W;4．GSM规范中，最大时间提前量TA=63bit，推算小区覆盖半径为35Km;5．G网设计中选用BCCH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f1和f2，其三阶互调产物公式为2f1-f2和2f2-f1。

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小。

12、GSM规范中，工程上同频干扰保护比C/I≥（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 ）KHZ。

14、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 ）。

17、TD-SCDMA系统是一个（TDD ）双工系统。

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

19、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）。

20、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）。

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。

射频工程师招聘笔试题及解答(某世界500强集团)

招聘射频工程师笔试题及解答(某世界500强集团)(答案在后面)一、单项选择题（本大题有10小题，每小题2分，共20分）1、射频工程师在进行信号传输设计时，以下哪个参数是衡量信号功率大小的？A、频率B、带宽C、增益D、信噪比2、在射频电路设计中，以下哪个元件主要用于实现信号的滤波功能？A、电感器B、电容器C、电阻器D、晶体管3、射频工程师在设计无线通信系统时，以下哪个参数通常用于衡量信号的带宽？A. 频率B. 相位C. 调制指数D. 带宽4、在射频系统中，以下哪个因素最有可能导致接收信号的信噪比（SNR）下降？A. 天线增益降低B. 增益均衡不良C. 接收机内部噪声增加D. 发射信号功率降低5、射频工程师在设计和调试无线通信系统时，以下哪个参数对于保证系统性能至关重要？A、发射功率B、接收灵敏度C、带宽D、数据速率6、在无线通信系统中，以下哪个因素不是导致多径效应的主要原因？A、建筑物反射B、地形起伏C、天线设计D、无线电波传播7、射频工程师在进行电路调试时，以下哪个指标是衡量信号强度的重要参数？A. 噪声系数（Noise Figure）B. 增益（Gain）C. 谐波失真（Harmonic Distortion）D. 谐波抑制比（Harmonic Suppression Ratio）8、在射频设计中，以下哪种技术用于减少电路中的噪声干扰？A. 交流耦合（AC Coupling）B. 直流耦合（DC Coupling）C. 噪声抑制滤波器（Noise Suppression Filter）D. 地平面设计（Ground Plane Design）9、射频工程师笔试题及解答试卷一、单项选择题9、在无线通信系统中，以下哪个参数表示信号从发射端到接收端传输过程中，信号强度下降的最大允许值？A. 频率带宽B. 覆盖范围C. 信号衰落D. 信号干扰二、多项选择题（本大题有10小题，每小题4分，共40分）1、以下哪些是射频工程师在设计和调试射频电路时常用的测量仪器？（）A. 示波器B. 网络分析仪C. 频谱分析仪D. 数字万用表E. 信号发生器2、以下哪些技术或方法可以用来提高射频电路的增益？（）A. 使用低噪声放大器B. 增加电路的反馈环路C. 提高电路的电源质量D. 选择合适的元器件E. 使用功率放大器3、射频工程师在进行电路设计时，以下哪些因素是影响射频电路性能的关键因素？（）A. 器件特性B. 电路布局C. 电源质量D. 材料选择E. 环境温度4、在射频信号处理中，以下哪些技术可用于提高信号质量？（）A. 前端放大B. 数字滤波C. 调制解调D. 数字信号处理E. 模拟信号处理5、射频工程师在进行电路设计时，以下哪些因素会影响电路的性能？（）A. 电路的工作频率B. 电路的带宽C. 电路的阻抗匹配D. 电路的散热设计E. 电路的制造工艺6、以下关于射频信号调制技术的说法，正确的是哪些？（）A. AM（调幅）调制是一种线性调制方式B. FM（调频）调制可以提高信号的带宽C. PM（调相）调制相对于AM调制具有更好的抗干扰能力D. PSK（相移键控）调制可以用来实现数字通信E. FSK（频移键控）调制与PSK调制相比，具有更高的频带利用率7、射频工程师在进行射频电路设计时，以下哪些因素会影响射频电路的性能？（）A. 信号频率B. 器件特性C. 印制电路板（PCB）设计D. 电源稳定性E. 环境温度8、以下关于射频功率放大器（PA）的描述，正确的是？（）A. 功率放大器的线性度越好，其输出信号质量越高B. 功率放大器的效率越高，其功耗越低C. 功率放大器的增益越高，其输出功率越大D. 功率放大器的温度系数越小，其稳定性越好E. 功率放大器的线性度越高，其线性失真越小9、射频工程师在设计和调试无线通信系统时，以下哪些因素会影响系统的性能？（）A. 天线增益B. 无线信道特性C. 发射功率D. 接收灵敏度E. 噪声水平三、判断题（本大题有10小题，每小题2分，共20分）1、射频工程师在设计和测试无线通信系统时，不需要考虑信号的多径效应。

射频笔试题

第一部分:1、理想空间,微波得波长λ与其频率f 得关系就就是什么？２、在介质中传输得微波波长λ1 与在空气中传输得微波波长λ2关系就就是什么？3、色散波（TE 波与TM 波)得相速就就是大于光速得,这就就是不就就是违背了相对论得观点?为什么?１、答:λ=c/ ｆ书本2、答:λ2＝（介质常数得２次方根)×λ１书本3、答:不知道第二部分:1、说两端口网络散射参数即S 参数得物理意义。

书本2、什么就就是反射系数？驻波系数与反射系数有何关系？书本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？4、在阻抗圆图上，从d减少源向负载方向移动逆时针与ｄ增加从负载向源方向移动顺时针,该如何转源图?5、在阻抗圆图中,圆图旋转一周,代表多少波长？6、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,则应在源与负载之间插一段特性阻抗为多少得四分之一波长得传输线？1、答:S11在2端口匹配得情况下1端口反射系数,Ｓ12在2端口匹配得情况下２端口到1端口得传输射系数S22在1端口匹配得情况下2端口反射系数S21在1端口匹配得情况下1端口到2端口传输射系数书本2、答:反射系数T就就是反射功率与入射功率之比,vsｗr=(1+T）/（1-T)3、答：Vswr=ＺL/ Z0 书本4、答:从源向负载方向移动逆时针从负载向源方向移动顺时针书本５、答:0、5个波长书本６、答:20欧书本第三部分：１、天线增益dBd与ｄBｉ各代表何含义,她们之间有何关系?2、天线就就是无源器件为何有增益?天线得增益与放大器得增益有何不同？３、在天线工程中，常把线极化天线分为水平极化与垂直极化,何为水平极化与垂直极化?1、答:ｄBi与ｄBd就就是考征增益得值（功率增益),两者都就就是一个相对值, 但参考基准不一样。

dＢi得参考基准为全方向性天线，dＢｄ得参考基准为偶极子，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。

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。

2021华为射频机考题目

华为射频技术方向笔试题目一、单项选择1.频综因电源波纹太大，近端有杂散，恶化积分相噪，从而恶化接收机灵敏度指标，下面措施有改善的是（）A.提高鉴相频率B.增大环路增益C.提升VCO相噪D.增大VCO输出功率2.驻波检测电路是通过测量正反向功率的差值的大小来确定驻波的大小。

正确错误3.输入信号带宽1MHz，功率谱密度为-60dBm/Hz,信噪比为20dB，通过一个增益为20dB、噪声系数为3dB的放大器，其输出信噪比为（）A.12dBB.17dBC.15dBD.20Db4.对于理想磁导体表面，下列描述正确的是（）A.磁场切向分量为零B.磁场、电场切向分量都为零C.电场切向分量为零 C.磁场、电场切向分量都不为零5.外差式接收机混频器前面往往会有一个镜频干扰滤波器，其主要作用是（）A.改善接收机噪声B.增加稳定性C.提高增益D.提高动态范围6.对于一个有源器件来说，以下哪些场景会导致噪声系数减小（）A.输入部分损耗减小B.增益减小C.环境温度增高D.线性提升7.一个放大器在1dB压缩点的输入功率为1dBm，输出功率为20dBm，该放大器的线性增益为（）A.19B.21C.20D.228.一个理想定向耦合器，耦合度为30dB,方向性为20dB，假如输入信号功率为1W,那么耦合端和隔离端输出信号功率各为多少？（）A.1 mW、100 mWB.1 mW、0.01 mWC.10 mW、1 mWD.0.1 mW、10 mW9.一段微带传输线的输入功率为30dBm，输出功率为29.7dBm，那么这段传输线的插入损耗是多少（）A.0.3 dBmB.0.5 dBmC.0.3dBD.0.5dB10.关于理想的T型结，下列说法正确的是（）A.输入端口匹配B.两输出端口隔离C.两输出端口匹配D.有耗11.两个发射通功率均为14，分别馈给两个间距为半波长的Patch天线，Patch单元天线的增益为5dBi。

则该简易1*2阵列的ERIP是多少dBm？（）A.25B.19C.22D.2812.下列传输线，工作带宽最窄的是（）A.同轴线B.带状线C.波导D.微带线13.天线增益与天线方向性系数的关系是（）A.天线增益=天线方向性系数*天线效率B.天线方向性系数=天线增益C.天线方向性系数=天线增益*天线效率D.天线方向性系数和天线增益没有关系14.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。

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