G3B – Maximum Usable Frequency; Lowest Usable Frequency; short path and long path propagation; determining propagation conditions; ionospheric refraction

- [[G3B01]] (D)
What is a characteristic of skywave signals arriving at your location by both short-path and long-path propagation? #card
	- A. Periodic fading approximately every 10 seconds
	- B. Signal strength increased by 3 dB
	- C. The signal might be cancelled causing severe attenuation
	- D. A slightly delayed echo might be heard
- [[G3B02]] (D)
What factors affect the MUF? #card
	- A. Path distance and location
	- B. Time of day and season
	- C. Solar radiation and ionospheric disturbances
	- D. All these choices are correct
- [[G3B03]] (A)
Which frequency will have the least attenuation for long-distance skip propagation? #card
	- A. Just below the MUF
	- B. Just above the LUF
	- C. Just below the critical frequency
	- D. Just above the critical frequency
- [[G3B04]] (A)
Which of the following is a way to determine current propagation on a desired band from your station? #card
	- A. Use a network of automated receiving stations on the internet to see where your transmissions are being received
	- B. Check the A-index
	- C. Send a series of dots and listen for echoes
	- D. All these choices are correct
- [[G3B05]] (A)
How does the ionosphere affect radio waves with frequencies below the MUF and above the LUF? #card
	- A. They are refracted back to Earth
	- B. They pass through the ionosphere
	- C. They are amplified by interaction with the ionosphere
	- D. They are refracted and trapped in the ionosphere to circle Earth
- [[G3B06]] (C)
What usually happens to radio waves with frequencies below the LUF? #card
	- A. They are refracted back to Earth
	- B. They pass through the ionosphere
	- C. They are attenuated before reaching the destination
	- D. They are refracted and trapped in the ionosphere to circle Earth
- [[G3B07]] (A)
What does LUF stand for? #card
	- A. The Lowest Usable Frequency for communications between two specific points
	- B. Lowest Usable Frequency for communications to any point outside a 100-mile radius
	- C. The Lowest Usable Frequency during a 24-hour period
	- D. Lowest Usable Frequency during the past 60 minutes
- [[G3B08]] (B)
What does MUF stand for? #card
	- A. The Minimum Usable Frequency for communications between two points
	- B. The Maximum Usable Frequency for communications between two points
	- C. The Minimum Usable Frequency during a 24-hour period
	- D. The Maximum Usable Frequency during a 24-hour period
- [[G3B09]] (C)
What is the approximate maximum distance along the Earth’s surface normally covered in one hop using the F2 region? #card
	- A. 180 miles
	- B. 1,200 miles
	- C. 2,500 miles
	- D. 12,000 miles
- [[G3B10]] (B)
What is the approximate maximum distance along the Earth’s surface normally covered in one hop using the E region? #card
	- A. 180 miles
	- B. 1,200 miles
	- C. 2,500 miles
	- D. 12,000 miles
- [[G3B11]] (A)
What happens to HF propagation when the LUF exceeds the MUF? #card
	- A. Propagation via ordinary skywave communications is not possible over that path
	- B. HF communications over the path are enhanced
	- C. Double-hop propagation along the path is more common
	- D. Propagation over the path on all HF frequencies is enhanced
- [[G3B12]] (D)
Which of the following is typical of the lower HF frequencies during the summer? #card
	- A. Poor propagation at any time of day
	- B. World-wide propagation during daylight hours
	- C. Heavy distortion on signals due to photon absorption
	- D. High levels of atmospheric noise or static