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