The Basic lessons · Radio wave propagation · B-007-008

Scatter Propagation: Filling the Skip Zone

Learn how radio signals can reach the 'dead zone' between ground wave and normal sky wave by bouncing off atmospheric irregularities. This lesson explains why these signals are weak and distorted, and which bands rely on this unique mode.

This lesson is part of SignalPrep Pro. The subsection's 11 exam questions are free to practise: practise B-007-008.

What this subsection asks

• What kind of unusual HF propagation allows weak signals from the skip zone to be heard?
• If you receive a weak, distorted signal close to the maximum usable frequency, what type of propagation is probably occurring?
• What type of VHF/UHF propagation depends upon small variations in density and water-vapour content?
• What makes HF scatter signals often sound distorted?
• Why are HF scatter signals usually weak?
• 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?
• On the HF bands, when is scatter propagation most likely involved?
• Tropospheric scatter frequently explains VHF/UHF communications well beyond the radio horizon. What makes this propagation mode possible?
• Meteor scatter is most effective on what band?
• What is the effect of scattering on a radio wave?
• In which frequency range is meteor scatter most effective for extended-range communication?