Ham Radio General Class Test Radio Wave Propagation 2

Question 1

What is the primary cause of sky-wave propagation on HF bands?

Accepted Answer

Refraction by the ionosphere

Answer

Sky-wave propagation occurs when HF signals are refracted (bent) back to Earth by the ionized layers of the ionosphere.

Question 2

Which ionospheric layer is primarily responsible for long-distance HF propagation during daylight hours?

Accepted Answer

F2 layer

Answer

The F2 layer, located at roughly 200-400 km altitude, provides the longest skip distances and is the primary layer for HF DX propagation.

Question 3

What is 'gray line' propagation?

Accepted Answer

Enhanced propagation along the terminator between daylight and darkness

Answer

The gray line (terminator) is the boundary between day and night where the D layer is absent but F layer ionization remains, enabling enhanced propagation.

Question 4

What effect does a sudden ionospheric disturbance (SID) have on HF communications?

Accepted Answer

It absorbs HF signals on the sunlit side of Earth, causing a radio blackout

Answer

A SID is caused by a solar X-ray flare that dramatically increases D-layer ionization, absorbing HF signals on the Earth's sunlit side.

Question 5

What is 'transequatorial propagation' (TEP)?

Accepted Answer

Propagation via F layer ionization across the magnetic equator, often reaching 50 MHz or above

Answer

TEP is a mode where signals propagate via enhanced F layer ionization on both sides of the magnetic equator and can extend into VHF frequencies.

Ham Radio General Class Test Practice Test

Ham Radio General Class Test Practice Test

Ham Radio General Class Test Radio Wave Propagation 2