BasicB-007-008-007
On the HF bands, when is scatter propagation most likely involved?
B
Answer
Interference and suppression
Type
A
When the F1 and F2 regions are combined
B
When you receive weak and distorted signals near the maximum usable frequency (MUF)
C
At night when propagation is poor
D
When the sunspot cycle is at a minimum and D-region absorption is high
Answer Notes
Scatter signals are characterized by a weak, fluttery, and distorted sound because the radio waves arrive at the receiving antenna from multiple randomized reflection points, resulting in multipath phase delays.
This effect is most noticeable when operating near the Maximum Usable Frequency (MUF). In this situation, the primary sky-wave skips completely over the receiver, leaving only the weak scattered energy to be heard in the skip zone. The distractors describe unrelated ionospheric conditions rather than the specific, observable indicators of scatter propagation.
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What type of propagation may allow a weak high frequency (HF) signal to be heard at a distance too far for ground-wave propagation but too near for normal sky-wave propagation?
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Tropospheric scatter frequently explains VHF/UHF communications well beyond the radio horizon. What makes this propagation mode possible?