Ham Radio General Class Test Radio Wave Propagation 4

Question 1

What is 'tropospheric scatter' (tropo scatter) propagation?

Accepted Answer

Scattering of VHF/UHF signals by turbulence and irregularities in the troposphere, enabling paths of 200-800+ km

Answer

Troposcatter uses the forward scatter of signals from irregularities in the troposphere to achieve beyond-line-of-sight paths at VHF/UHF, typically 200-800+ km.

Question 2

What is 'sporadic-E' (Es) propagation and what frequencies does it most affect?

Accepted Answer

Unpredictable clouds of ionization in the E layer that support propagation on 6 meters, 10 meters, and even 2 meters

Answer

Sporadic-E consists of intense, localized patches of ionization at E-layer heights that can support propagation on frequencies from HF into VHF, often unexpectedly.

Question 3

How does antenna take-off angle affect skip distance on HF?

Accepted Answer

Higher take-off angles produce shorter skip distances; lower angles produce longer skip distances

Answer

A high take-off angle returns a sky-wave closer to the transmitter (short skip), while a low take-off angle at the horizon returns a wave much farther away (long skip/DX).

Question 4

What is 'ionospheric tilt' and how can it affect communications?

Accepted Answer

An uneven or tilted ionospheric layer that can cause signals to be reflected in unexpected directions

Answer

Ionospheric tilt, often caused by solar terminator gradients or geomagnetic activity, can deflect signals off their expected path, enabling unusual contacts or causing propagation anomalies.

Question 5

What is the Lowest Usable Frequency (LUF) determined by?

Accepted Answer

The frequency below which D-layer absorption makes a path unusable despite adequate MUF

Answer

The LUF is the lowest frequency on which D-layer absorption is low enough to allow adequate signal strength over a given path — it rises during solar events.

Ham Radio General Class Test Practice Test

Ham Radio General Class Test Practice Test

Ham Radio General Class Test Radio Wave Propagation 4