Page:Electronics Technician - Volume 7 - Antennas and Wave Propagation - NAVEDTRA 14092.pdf/106

 1-11. At what frequencies does the combination of the earth's surface and. the D layer act as a waveguide?
 * Vlf
 * Lf
 * Mf
 * Hf

1-12. The D layer loses its 1-18 absorptive qualities at frequencies above what level?
 * 1) 30 MHZ
 * 2) 20 MHZ
 * 3) 10 MHZ
 * 4) 3 MHZ

1-13. What is the approximate range of the E layer above the earth's surface?
 * 1) 30-54 miles
 * 2) 55-90 miles
 * 3) 91-130 miles
 * 4) 131-160 miles

1-14. Frequencies above what level pass through the E layer unaffected?
 * 1) 50 MHZ
 * 2) 100 MHZ
 * 3) 150 MHZ
 * 4) 200 MHZ

1-15. During daylight hours, the F layer will divide into how many separate layers?
 * 1) Five
 * Two
 * 1) Three
 * 2) Four

1-16. Most high-frequency, long-range communications occur in what layer(s) of the ionosphere?
 * D
 * E
 * F
 * H

1-17. Which. of the following is NOT a factor for radio wave refraction?
 * 1) Ionization density of the layer
 * 2) Frequency of the radio wave
 * 3) Angle of incidence
 * 4) Transmitter power

1-18. For any given ionized layer, the critical frequency is just below the escape point.
 * 1) True
 * 2) False

1-19. The critical angle for radio wave propagation depends on what two factors?
 * 1) Angle of incidence and layer density only
 * 2) Layer density and wavelength only
 * 3) Angle of incidence and wavelength only
 * 4) Wavelength and antenna height only

1-20. What term best describes the area located between the transmitting antenna and the point where the sky wave first returns to the earth?
 * 1) Ground
 * 2) Skip zone
 * 3) Skip distance
 * 4) Ace area

1-21. Which of the following factors will affect the outer limits of the skip zone?
 * 1) Frequency
 * 2) Sunspot activity
 * 3) Angle of transmission
 * 4) All of the above

1-22. Radio waves reflecting from the earth's surface or the ionosphere, 180 degrees out of phase, have what effect, if any, at the receiving station?

2
 * 1) The signal will be weak or faded
 * 2) The signal will be stronger
 * 3) The signal will be garbled
 * 4) None