Ham Radio General Class Practice Test

What type of radio wave propagation allows a signal to be detected at a distance too far for ground wave propagation but too near for normal sky-wave propagation?

1. Faraday rotation

2. Scatter

3. Sporadic-E skip

4. Short-path skip

The correct answer is: Scatter

Scatter propagation refers to a phenomenon where radio waves are scattered off irregularities in the ionosphere or other sources, allowing signals to be detected over distances that are neither suitable for ground wave propagation nor conventional sky-wave propagation. This type of propagation can occur at relatively short distances by utilizing the scattered signals that reflect off atmospheric irregularities, making it possible for signals to reach beyond the typical range of ground waves which only travel a few hundred kilometers at most, while also avoiding the longer distances associated with sky-wave propagation, which often involves higher layer reflections. In the context of the other options, Faraday rotation involves changes in the polarization of radio waves as they pass through a magnetic field, which doesn't directly relate to distance propagation. Sporadic-E skip refers to short-lived, high-frequency propagation due to the presence of E-layer ionization that allows for long-distance communications, while short-path skip is a term more commonly used to describe direct sky-wave propagation between two points at a specific angle of incidence. Neither of these adequately describes the intermediate range of propagation that scatter can achieve.