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Flashcards in Propagation Modes - T3C Deck (11)
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1
Q

Why are “direct” (not via a repeater) UHF signals rarely heard from stations outside your local coverage area?

A

UHF signals are usually not reflected by the ionosphere

2
Q

Which of the following might be happening when VHF signals are being received from long distances?

A

Signals are being refracted from a sporadic E layer

3
Q

What is a characteristic of VHF signals received via auroral reflection?

A

The signals exhibit rapid fluctuations of strength and often sound distorted

4
Q

Which of the following propagation types is most commonly associated with occasional strong over-the-horizon signals on the 10, 6, and 2 meter bands?

A

Sporadic E

5
Q

What is meant by the term “knife-edge” propagation?

A

Signals are partially refracted around solid objects exhibiting sharp edges

6
Q

What mode is responsible for allowing over-the-horizon VHF and UHF communications to ranges of approximately 300 miles on a regular basis?

A

Tropospheric scatter

7
Q

What band is best suited to communicating via meteor scatter?

A

6 meters

8
Q

What causes “tropospheric ducting”?

A

Temperature inversions in the atmosphere

9
Q

What is generally the best time for long-distance 10 meter band propagation?

A

During daylight hours

10
Q

What is the radio horizon?

A

The distance at which radio signals between two points are effectively blocked by the curvature of the Earth

11
Q

Why do VHF and UHF radio signals usually travel somewhat farther than the visual line of sight distance between two stations?

A

The Earth seems less curved to radio waves than to light