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?
- 30 MHZ
- 20 MHZ
- 10 MHZ
- 3 MHZ
1-13. What is the approximate range of the E layer above the earth's surface?
- 30-54 miles
- 55-90 miles
- 91-130 miles
- 131-160 miles
1-14. Frequencies above what level pass through the E layer unaffected?
- 50 MHZ
- 100 MHZ
- 150 MHZ
- 200 MHZ
1-15. During daylight hours, the F layer will divide into how many separate layers?
- Five
- Two
- Three
- 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?
- Ionization density of the layer
- Frequency of the radio wave
- Angle of incidence
- Transmitter power
1-18. For any given ionized layer, the critical frequency is just below the escape point.
- True
- False
1-19. The critical angle for radio wave propagation depends on what two factors?
- Angle of incidence and layer density only
- Layer density and wavelength only
- Angle of incidence and wavelength only
- 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?
- Ground
- Skip zone
- Skip distance
- Ace area
1-21. Which of the following factors will affect the outer limits of the skip zone?
- Frequency
- Sunspot activity
- Angle of transmission
- 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?
- The signal will be weak or faded
- The signal will be stronger
- The signal will be garbled
- None
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