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Text File | 1992-01-26 | 8KB | 327 lines

FCC GENERAL Exam Question Pool. Subelement 3BC. Radio Wave Propagation. ? Questions. --------------------------------------------------- 3BC 1.6 C What is the maximum distance along the earth's surface that can normally be covered in one hop using the F2 layer? A. Approximately 180 miles B. Approximately 1200 miles C. Approximately 2500 miles D. No distance. This layer does not support radio communication 3BC 1.7 B What is the maximum distance along the earth's surface that can be covered in one hop using the E layer? A. Approximately 180 miles B. Approximately 1200 miles C. Approximately 2500 miles D. No distance. This layer does not support radio communication 3BC 1.9 B What is the average height of maximum ionization of the E layer? A. 45 miles B. 70 miles C. 200 miles D. 1200 miles 3BC 1.10 A During what part of the day, and in what season of the year can the F2 layer be expected to reach its maximum height? A. At noon during the summer B. At midnight during the summer C. At dusk in the spring and fall D. At noon during the winter 3BC 1.13 D What is the critical angle, as used in radio wave propagation? A. The lowest take off angle that will return a radio wave to earth under specific ionospheric conditions B. The compass direction of the desired DX station from your location C. The 180-degree-inverted compass direction of the desired DX station from your location D. The highest take off angle that will return a radio wave to earth during specific ionospheric conditions 3BC 2.3 C What is the main reason that the 160-, 80-, and 40-meter wavelength amateur bands tend to be useful for only short- distance communications during daylight hours? A. Because of a lack of activity B. Because of auroral propagation C. Because of D-layer absorption D. Because of magnetic flux 3BC 2.4 C What is the principal reason the 160-meter through 40-meter wavelength bands are useful for only short- distance radio communications during daylight hours? A. F-layer bending B. Gamma radiation C. D-layer absorption D. Tropospheric ducting 3BC 3.3 B If the maximum usable frequency on the path from Minnesota to Africa is 22-MHz, which band should offer the best chance for a successful QSO? A. 10 meters B. 15 meters C. 20 meters D. 40 meters 3BC 3.4 C If the maximum usable frequency on the path from Ohio to West Germany is 17-MHz, which band should offer the best chance for a successful QSO? A. 80 meters B. 40 meters C. 20 meters D. 2 meters 3BC 5.1 B Over what periods of time do sudden ionospheric disturbances normally last? A. The entire day B. A few minutes to a few hours C. A few hours to a few days D. Approximately one week 3BC 5.2 A What can be done at an amateur station to continue radio communications during a sudden ionospheric disturbance? A. Try a higher frequency B. Try the other sideband C. Try a different antenna polarization D. Try a different frequency shift 3BC 5.3 B What effect does a sudden ionospheric disturbance have on the daylight ionospheric propagation of HF radio waves? A. Disrupts higher-latitude paths more than lower-latitude paths B. Disrupts transmissions on lower frequencies more than those on higher frequencies C. Disrupts communications via satellite more than direct communications D. None. Only dark (as in nighttime) areas of the globe are affected 3BC 5.4 C How long does it take a solar disturbance that increases the sun's ultraviolet radiation to cause ionospheric disturbances on earth? A. Instantaneously B. 1.5 seconds C. 8 minutes D. 20 to 40 hours 3BC 5.5 A Sudden ionospheric disturbances cause increased radio wave absorption in which layer of the ionosphere? A. D layer B. E layer C. F1 layer D. F2 layer 3BC 6.2 B What is a characteristic of backscatter signals? A. High intelligibility B. A wavering sound C. Reversed modulation D. Reversed sidebands 3BC 6.4 D What makes backscatter signals often sound distorted? A. Auroral activity and changes in the earth's magnetic field B. The propagation through ground waves that absorb much of the signal's clarity C. The earth's E-layer at the point of radio wave refraction D. The small part of the signal's energy scattered back to the transmitter skip zone through several radio-wave paths 3BC 6.5 B What is the radio wave propagation phenomenon that allows a signal to be detected at a distance too far for ground wave propagation but too near for normal sky wave propagation? A. Ground wave B. Scatter C. Sporadic-E skip D. Short path skip 3BC 6.6 D When does ionospheric scatter propagation on the HF bands most often occur? A. When the sunspot cycle is at a minimum B. At night C. When the F1 and F2 layers are combined D. At frequencies above the maximum usable frequency 3BC 7.1 B What is solar flux? A. The density of the sun's magnetic field B. The radio energy emitted by the sun C. The number of sunspots on the side of the sun facing the earth D. A measure of the tilt of the earth's ionosphere on the side toward the sun 3BC 7.2 D What is the solar-flux index? A. A measure of past measurements of solar activity B. A measurement of solar activity that compares daily readings with results from the last six months C. Another name for the American sunspot number D. A measure of solar activity that is taken daily 3BC 7.3 A What is a timely indicator of solar activity? A. The 2800-MHz solar flux index B. The mean Canadian sunspot number C. A clock set to Coordinated Universal Time D. Van Allen radiation measurements taken at Boulder, Colorado 3BC 7.4 D What type of propagation conditions on the 15-meter wavelength band are indicated by a solar-flux index value of 60 to 70? A. Unpredictable ionospheric propagation B. No ionospheric propagation is possible C. Excellent ionospheric propagation D. Poor ionospheric propagation 3BC 7.5 D A solar flux index in the range of 90 to 110 indicates what type of propagation conditions on the 15-meter wavelength band? A. Poor ionospheric propagation B. No ionospheric propagation is possible C. Unpredictable ionospheric propagation D. Good ionospheric propagation 3BC 7.6 A A solar flux index of greater than 120 would indicate what type of propagation conditions on the 10-meter wavelength band? A. Good ionospheric propagation B. Poor ionospheric propagation C. No ionospheric propagation is possible D. Unpredictable ionospheric propagation 3BC 7.7 D For widespread long distance openings on the 6-meter wavelength band, what solar-flux index values would be required? A. Less than 50 B. Approximately 75 C. Greater than 100 D. Greater than 250 3BC 7.8 C If the MUF is high and HF radio communications are generally good for several days, a similar condition can usually be expected how many days later? A. 7 days B. 14 days C. 28 days D. 90 days 3BC 10.1 D What is a geomagnetic disturbance? A. A sudden drop in the solar-flux index B. A shifting of the earth's magnetic pole C. Ripples in the ionosphere D. A dramatic change in the earth's magnetic field over a short period of time 3BC 10.2 A Which latitude paths are more susceptible to geomagnetic disturbances? A. Those greater than 45 degrees latitude B. Those less than 45 degrees latitude C. Equatorial paths D. All paths are affected equally 3BC 10.3 B What can be the effect of a major geomagnetic storm on radio communications? A. Improved high-latitude HF communications B. Degraded high-latitude HF communications C. Improved ground-wave propagation D. Improved chances of ducting at UHF 3BC 10.4 D How long does it take a solar disturbance that increases the sun's radiation of charged particles to affect radio wave propagation on earth? A. The effect is instantaneous B. 1.5 seconds C. 8 minutes D. 20 to 40 hours -------------------------------------------------- End of Subelement 3BC.