Self-Test
& Supply the missing word(s) in each statement.
Choose the letter that best answers each question.
1. Microwaves are frequencies above _____ GHz,
2. The main advantage of microwaves is that more of the _____ is available for signals.
3. List seven reasons why microwaves are more difficult to work with than lower frequency signals.
4. The applications most commonly found in the microwave region are _____ and _____.
5. List four popular uses for microwaves.
6. The government agency that regulates radio communications in the United States is the _____.
7. Name four techniques that have helped squeeze more signals into the given spectrum.
8. Two reasons why conventional transistors won't work at microwave frequencies are _____ and _____.
9. At microwave frequencies, conventional components like resistors, capacitors, and inductors act like _____ circuits.
10. The TV channels 2 to 13 occupy a total bandwidth of about 72 MHz. At a frequency of 200 MHz, this represents a bandwidth of _____ percent of the spectrum space. At 2 GHz, it represents _____ percent.
11. True or false. Twin lead is not used at microwave frequencies.
12. The main disadvantage of using coax for microwave signals is its high _____.
13. Coax is not used beyond frequencies of about _____ GHz.
14. A hollow metal pipe used to carry microwaves is called a(n) _____.
15. Two types of transmission line made of PCB material used to produce tuned circuits and filters are _____.
16. The two ways to couple or extract energy from a waveguide are by using a _____ or a _____.
17. A waveguide acts as a(n) _____ filter.
18. A rectangular waveguide has a width of 1.2 in. and a height of 0.7 in. The waveguide will pass all signals above _____ GHz.
19. A waveguide has a cutoff frequency of 5 GHz.
a. True or false. It will pass a signal of 8 GHz.
b. True or false. It will pass a signal of 3 GHz.
20. The magnetic and electric fields in a waveguide are designated by the letters _____ and _____, respectively.
21. The basic operating mode of most waveguides is designated _____.
22. If the H field in the waveguide is perpendicular to the direction of signal travel, the mode is said to be _____.
23. A one-half wavelength section of waveguide shorted at both ends creates a(n) _____.
24. A cavity resonator acts as a(n) _____ circuit.
25. Resonant cavities are used as _____.
26. Mechanically varying the cavity's dimensions allows its _____.
27. List three reasons why conventional diodes and transistors do not work in the microwave region.
28. A point-contact diode has a(n) _____ anode and a(n) _____ cathode.
29. A microwave diode with an N-type silicon cathode and a metal anode forming a junction is called a(n) _____ diode.
30. The most common application of microwave signal diodes is in _____ circuits.
31. A diode that acts like a VVC is a(n) _____ diode.
32. Two types of diodes widely used as frequency multipliers are the _____ and _____ diodes.
33. A diode with no junction that is widely used with a cavity resonator to form an oscillator is the_____ diode.
34. The _____, _____, and _____ diodes are also used as oscillators.
35. Microwave diodes that cause a current decrease for a voltage increase have what is known as a(n) _____ characteristic.
36. An IMPATT diode operates with _____ (forward, reverse) bias.
37. A tunnel diode operates with _____ (forward, reverse) bias.
38. True or false. Klystrons can be used as amplifiers or oscillators.
39. True or false. A magnetron operates as an amplifier.
40. A TWT is an _____ (amplifier, oscillator).
41. The operating frequency of klystrons and magnetrons is determined by _____.
42. The cavities in a klystron produce _____ modulation of the electron beam.
43. In a klystron amplifier, the input is applied to the _____ cavity and the output taken from the _____ cavity.
44. A one-cavity klystron that oscillates is known as a(n) _____ klystron.
45. Low-power klystrons are being replaced by _____, and high-power klystrons are being replaced by _____.
46. A(n) _____ causes the electrons in a magnetron to travel in circular paths.
47. Two major applications of magnetrons are in _____.
48. The TWT is a microwave _____.
49. Density modulation of the electron beam in a TWT is produced by a(n) _____.
50. The major benefit of a TWT is its wide _____.
51. The most commonly used microwave antenna is the _____ antenna.
52. Increasing the length of a horn antenna causes its gain to _____ and its beam width to _____.
53. A horn antenna is six wavelengths long at 8 GHz. That length is _____ in.
54. The beam width of a horn antenna is usually in the _____ to degree _____ range. ,
55. The width of a horn antenna is 8 cm. The height is 6 cm. The operating frequency is 8 GHz. The beam angle is _____ degrees. The gain is _____ dB. Assume k = 0.5.
56. Horn antennas have _____ (narrow, wide) bandwidth.
57. The geometric shape of a microwave reflector is a(n) _____.
58. In order for a dish, reflector to work, the antenna must be located at the _____ of the dish.
59. The antenna used with a dish reflector is usually a(n) _____.
60. A parabolic reflector antenna has a diameter of 9 m. The frequency of operation is 8 GHz. The gain is _____ dB. The beam width is _____ °.
61. The effect of a parabolic reflector on an antenna is to _____ gain and _____ beam width.
62. A dish with a horn at its center and a small reflector at the focal point is said to use _____ feed.
63. The benefits of a helical antenna are its _____ and _____.
64. The gain of a helical antenna is typically in the _____ to _____ –dB range.
65. The beam width of a helical antenna is in the _____ to _____ degree range.
66. The helical antenna radiates a(n) _____ polarized wave.
67. The acronym RHCP means _____.
68. A popular omni directional microwave antenna is the _____.
69. True or false. A helical antenna will receive either vertical or horizontally polarized signals.
True or false. An RHCP antenna can receive a signal from an LHCP antenna.
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