Ham Radio General Class Test FREE Ham Radio General Class Test Radio Wave Propagation Questions and Answers 2 — Questions and Answers
Question 1: What is the primary cause of ionospheric absorption of HF radio signals?
- D-layer ionization during daylight hours (Correct answer)
- F2-layer recombination at night
- Sporadic E-layer formation
- Tropospheric ducting inversions
Correct answer: D-layer ionization during daylight hours
The D layer, which forms during daylight, absorbs HF signals rather than refracting them, particularly at lower HF frequencies.
Question 2: Which propagation mode is most commonly used for VHF communications beyond line-of-sight during certain weather conditions?
- Tropospheric ducting (Correct answer)
- Gray-line propagation
- Meteor scatter
- Near Vertical Incidence Skywave
Correct answer: Tropospheric ducting
Tropospheric ducting occurs when temperature inversions in the lower atmosphere bend VHF and UHF signals beyond the normal horizon.
Question 3: What does the term 'Maximum Usable Frequency' (MUF) refer to in HF propagation?
- The highest frequency that will be refracted back to Earth by the ionosphere for a given path (Correct answer)
- The maximum power output allowed on a frequency
- The highest frequency a transceiver can tune to
- The frequency with the least amount of noise
Correct answer: The highest frequency that will be refracted back to Earth by the ionosphere for a given path
The MUF is the highest frequency at which a radio wave can be refracted by the ionosphere back to Earth for a specific transmission path at a given time.
Question 4: What effect does solar flux index (SFI) have on HF propagation?
- Higher SFI generally improves HF propagation on higher frequency bands (Correct answer)
- Higher SFI reduces all HF propagation
- SFI only affects VHF propagation
- SFI has no measurable effect on radio propagation
Correct answer: Higher SFI generally improves HF propagation on higher frequency bands
A higher solar flux index indicates greater solar radiation, which increases ionospheric ionization and supports propagation at higher HF frequencies.
Question 5: What is the approximate speed at which radio waves travel through free space?
- 300,000,000 meters per second (Correct answer)
- 150,000,000 meters per second
- 300,000 meters per second
- 186,000 meters per second
Correct answer: 300,000,000 meters per second
Radio waves travel at the speed of light, approximately 300,000,000 meters per second (3 x 10^8 m/s) in free space.
Question 6: Which ionospheric layer is primarily responsible for long-distance HF communication at night?
- F2 layer (Correct answer)
- D layer
- E layer
- Troposphere
Correct answer: F2 layer
At night the D and E layers dissipate, leaving the F2 layer as the primary refracting layer for long-distance HF skywave propagation.
Ham Radio General Class Test FREE Ham Radio General Class Test Radio Wave Propagation Questions and Answers 2
What is the primary cause of ionospheric absorption of HF radio signals?