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1. In a radio receiver with simple AGCAns. An increase in signal strength produces more AGC

2. In a broadcast superheterodyne receiver, the ______Ans. Mixer input must ber tuned to the signal frequency

3. To prevent overloading of the last IF amplifier in a receiver, one should use ___Ans. Variable sensitivity

4. A superheterodyne receiver with an IF of 450 kHz is tuned to a signal at 120kHz. The image frequency is Ans. 2100 kHz

5. In a ratio detectorAns. The linearity is worse than in a phase discriminator

6. The typical squelch circuit is cuts offAns. An audio amplifier when the carrier is absent

7. The controlled oscillator synthesizer is sometimes preferred over the direct oe becauseAns. It is relatively free of spurious frequencies

8. The fequency generated by each decade in a direct frequeny synthesizer is much higher than the frequency shown; this is done to Ans. Reduce the spurious frequency problem

9. Indicate which of the following could not demodulate SSBAns. Phase discriminator

10. If an FET is used as the forst AF amplifier in a transistor receiver, this will have have the effect of

Ans. Reducing the effect of negative-peak clipping

11. The image frequency of a superheterodyne receiverAns. Is not rejected by the IF tuned circuits

12. One of the main functions of the RF amplifier in a superheterodyne receiver is toAns. Improve the rejection of the image frequency

13. A receiver has poor IF selectivity. It will therefore also have poorAns. Blocking

14. Three-point tracking is achived withAns. Padder capacitor

15. A low ratio of the ac to the dc load impedance of a diode detector results in Ans. Negative-peak clipping

16. One of the following cannot be used to demodulate SSB:Ans. Bipolar transistor balanced modulator

17. A ship-to-ship communocation system is plagued by fading. The best solution seems to be use ofAns. Frequency diversity

18. A range of microwave frequiencies more easily passed by the atmosphere than are the others is called a Ans. Window

19. Frequencies in the UHF range normally propagate by means ofAns. Space waves

20. Tropospheric scatter is used with frequencies in the following rangeAns. UHF

21. The ground wave eventually disapperas, as one moves away from the transmitter, because ofAns. Tilting

22. In electromagnetic waves, polarizationAns. Is due to transverse nature of the waves

23. As electromagnetic waves travel in free space, only one of the following can happen to them:Ans. Attenuation

24. The absorption of radio waves the atmosphere depends onAns. Their frequency

25. Electromagnetic waves are by theyAns. Pass into a medium of different dielectric constant

26. Diffraction of electromagnetic wavesAns. May occur around the edge of sharp obstacle

27. When microwave signals follow the curvature of the earth, this is known asAns. Ducting

28. Helical antennas are often used for satellite tracking at VHF because ofAns. Faraday Effect

29. An ungrounded antenna near the groundAns. Acts as an antenna array

30. One of the following consists of nonresonant antennasAns.the rhombic antenna

31. One of the following is very useful as a multiband HF receiving antenna. This is theAns. Log-periodic

32. Which of the following antennas is best excited from a waveguide?Ans. Horn

33. Indicate which of the following reasons for using a counterpoise with antennas is false:Ans. Protection of personnel working underneath

34. One of the following is not a reason for the use of an antenna coupler.Ans. To prevent radiation of the local oscillator

35. Indicate the antenna that is not widebandAns. Marconi

36. Antenna that is circularly polarized is theAns. Helical

37. Top loading is sometimes used with an antenna in order increase itsAns. Effective height

38. A helical antenna is used is for satellite tracking because of itsAns. Circular polarization

39. The wavelength of a wave in a waveguideAns. Greater than in free space

40. Cylindrical cavity resonators are not used with klystrons because they haveAns. Harmonically related resonant frequencies

41. A directional coupler with three or more holes is sometimes used in preference to the two-hole couplerAns. To increase the bandwidth of the system

42. A ferrite isAns. A nonconductor with magnetic properties

43. The maximum power that may be handled by ferrite component is limited by theAns. Curie temperature

44. A PIN diode isAns. Suitable for use as a microwave switch

45. A duplexer is usedAns. To allow the one antenna to be used for reception or transmission without mutual interference

46. For some applications, circular waveguides may be preferred to rectangular ones because ofAns. Lower attenuation

47. In order to reduce cross-sectional dimensions, the waveguide to use isAns. Ridged

48. A parametric amplifier must be cooledAns. To improve the noise performance

49. A ruby maser amplifier must be cooledAns. Because it cannot operate at room temperature

50. A disadvantage of microstrip compared with stripline is that microstripAns. Is more likely to radiate

51. The transmission system using two ground planes isAns. Stripline

52. Surface acoustic waves propagate inAns. Quartz crystal

53. SAW devices may be used asAns. Filters

54. For best low-level noise performance in the X-band, an amplifier should useAns. A step-recovery diode

55. The biggest advantage i the TRAPATT didoe over the IMPATT diode is itsAns. Higher effieciency

56. Indicate which of the following diodes will produce the highest pulsed power output:Ans. RIMPATT

57. Indicate which of the following diodes does not use negative resistance in its operationAns. Backward

58. One of the following is not used as a mircowave mixer or detectorAns. PIN diode

59. One of the following microwave diodes is suitable for very low-power oscillators only:Ans. Tunnel

60. The transferred-electon bulk effect occurs inAns. Gallium arsenide

61. The gain-bandwidth frequency of a microwave transistor, fT is the frequency at which theAns. Beta of the transistor falls to unity

62. For a microwave transistor to operate at the highest frequencies, the (indicate the false answer)Ans. Emitter area must be large

63. If high-order frequency multiplication is required from a diode multiplier,Ans. A step-recovery diode must be used

64. A parametric amplifier has an input and output frquency of 2.25 GHz, and is pumped at 4.5 GHz. It is aAns. Degenerate amplifier

65. Traveling-wave parametric amplifiers are used to

Ans. Provide greater bandwidth

66. A parametric amplifier sometimes uses a circulator toAns. Pervent noise feedback

67. The nondegenerate one-port parametric amplifier should gave a high ratio of pump to signal frequency because thisAns. Yields a low noise figure

68. The tunnel diodeAns. Uses a high doping level to provide a narrow junction

69. A tunnel didode loosely coupled to its cavity in order toAns. Increase the frequency stability

70. He negative resistance in a tunnel diodeAns. Is available between the peak and valley points

71. The biggest advantage of gallium antimonide over germanium for tunnel-diode use is that the former has aAns. Larger voltage swing

72. Negative resistance is obtained ith a Gunn doode because ofAns. Electron transfer o a less mobile energy level

73. For Gunn diodes, gallium arsenide is preferred to silicon because the formerAns. Has a suitable empty energy band, which silicon does not have

74. The biggest disadvantage of the IMPATT diode is itsAns. High noise

75. The magnetic field is used with a ruy maser toAns. Provide frequency adjustment

76. The ruby maser has been preferred to the ammonia maser for microwave amplification, because the former hasAns. A much greater bandwidth

77. Parametric amplifiers and masers are similar to each other in that both (indicate false statement)Ans. Must be cooled down to a few kelvins

78. A maser RF amplifier is not really suitable forAns. Radar

79. The ruby laser differs fromt he ruby maser in that the formerAns. Is an oscillator