Self-Test
& Supply the missing word(s) in each statement.
Choose the letter that best answers each question.
1. The two basic types of transmission line are _____.
2. If one wire of a transmission line is connected to ground, the line is said to be _____.
3. The distance that a signal travels during one cycle is called the _____.
4. One wavelength that a frequency of 450 MHz is m _____.
5. A line 4 in. long represents one-half wavelength at a frequency of _____ GHz.
6. The physical dimensions of a transmission line determine its _____.
7. To a generator, a transmission line looks like a(n) _____ made up of distributed _____ and _____.
8. A coax line has a shield braid with an inside diameter of 0.2 in. and a center conductor with a diameter of 0.057 in. The characteristic impedance is _____V.
9. The attenuation of 250 ft of RG-11U coax at 100 MHz is _____ dB. (SeeFig.9-7) (page 211-Frenzel)
10. For optimum transfer of power from a generator to a load of 52 V, the transmission line impedance should be _____V.
11. The current and voltage along a properly matched line are _____.
12. If a transmission line is not terminated in its characteristic impedance, _____ will develop along the line
13. If a load and line have mismatched impedances, power not absorbed by the load will be _____.
14. Patterns of voltage and current variations along, a transmission line with a mismatched load are known as _____.
15. A 52-V coax bas a 36-V antenna load. The SWR is _____.
16. If the load and line impedances are matched, the SWR will be _____.
17. All incident power on a line will be reflected if the line is _____ or _____ at its end.
18. The ratio of the reflected voltage to the incident voltage on a transmission line is called the _____.
19. The maximum voltage along a transmission line is 150V, and the minimum voltage is 90V. The SWR is _____.The reflection coefficient is _____.
20. The reflection coefficient of a transmission line is 0.75. The SWR is _____.
21. An open or shorted transmission line will have a reflection coefficient of _____ and an SWR of _____.
22. Transmission lines, one-quarter or one haIf wavelength can be used as _____.
23. A transmission line bas an SWR of 1.75. The power applied to the line, is 90 W. The amount of reflected power is _____ W.
24. A shorted quarter-wave line looks like a(n) _____ impedance to the generator.
25. The following lines look like a series resonant circuit: a _____ l/4 line; a _____ l/2 line.
26. Transmission lines less than l/4 or between l/4 and l/2 act like _____ or _____.
27. An open transmission line 6 in. long acts as a _____ resonant circuit at a frequency of 492 MHz.
28. A coax bas a velocity factor of 0.68. One half wavelength of this coax at 120 MHz is _____ ft long.
29. Radio waves are made up of _____ and _____ fields.
30. The polarization of a radio wave depends upon the position of its _____ with respect to the earth's surface.
31. The antenna is connected to the transmitter or receiver by a(n) _____.
32. A radio wave has its magnetic field horizontal to the earth. It is, therefore, _____ polarized.
33. One of the most widely used and simplest antennas is the half-wave _____.
34. The length of a doublet antenna at 150 MHz is _____ ft.
35. The feed impedance of a dipole antenna is approximately, _____ V.
36. The horizontal radiation pattern of a dipole looks like a(n) _____.
37. The measure of an antenna's directivity is _____.
38. An antenna that radiates equally well in all horizontal directions is said to be _____.
39. A quarter-wave vertical antenna is commonly known as a(n) _____ antenna.
40. The length of a quarter-wave vertical antenna at 890 MHz is _____ in.
41. For proper operation of a vertical antenna, the shield of the feed coax must make a good connection to _____ or a set of quarter-wave wires called _____.
42. The horizontal radiation pattern of a quarter-wave vertical is a(n) _____.
43. The feed impedance of a quarter-wave vertical is approximately _____V.
44. An antenna that transmits or receives equally well in two opposite directions is said to be _____.
45. A unidirectional antenna transmits best in _____ direction(s).
46. A directional antenna that focuses the energy into a narrow beam has _____ since it effectively amplifies the signal.
47. To have gain and directivity, an antenna must have two or more _____.
48. List two basic types of antenna arrays.
49. The three basic elements in a Yagi antenna are _____.
50. The two parasitic elements in a beam antenna are the _____.
51. A Yagi may have one or more _____ elements.
52. The beam width of a Yagi is usually in the range of _____ to _____ degrees.
53. The length of the driven element in a Yagi at 222 MHz is _____ ft.
54. List three kinds of driven arrays.
55. True or false. Yagis and driven arrays may be operated either horizontally or vertically.
56. A popular wideband driven array is the _____ array.
57. An impedance-matching circuit used to make the antenna, transmission line, and transmitter impedances match is the _____.
58. A transformer used for impedance matching is the _____.
59. A quarter-wavelength section of transmission line used for impedance matching is called a(n) _____.
60. A coax balun has an impedance-matching ratio of _____.
61. A quarter-wavelength of coax with a velocity factor of 0.7 at 220 MHz is _____ in.
62. List the three paths that a radio signal may take through space.
63. A radio wave that propagates near the surface of the earth is called a(n) _____ or _____ wave.
64. The radio wave that is refracted by the ionosphere is known as a(n) _____ wave.
65. A radio wave that propagates only over line-of-sight distances is called a(n) _____ or _____ wave.
66. The surface wave is effective only at frequencies below about _____ MHz.
67. The upper part of the earth's atmosphere ionized by the sun that affects radio waves is called the _____.
68. The _____ layer has the greatest effect on a radio signal.
69. The ionized atmosphere causes radio waves at some frequencies to be _____.
70. True or false. Radio waves are easily reflected by large objects.
71. True or false. The ionosphere reflects radio waves.
72. Only signals in the _____ to _____ MHz range are significantly affected by the ionosphere.
73. Worldwide radio communications is possible thanks to _____ transmission.
74. The VHF, UHF, and microwave signals travel in a(n) _____.
75. To increase transmission distances at VHF and above, special stations called are _____ used.
A microwave relay station contains a(n) _____ and a(n) _____ operating on different frequencies.
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