Practice
Propagation — Practice
How signals actually travel — ground wave, sky wave and everything the ionosphere does to them. Untimed topic practice with a full explanation after every question, so a wrong answer becomes a study note rather than a dead end.
Questions
8
Time limit
Untimed
Pass mark
60%
Before you start
- Untimed. The explanation appears as soon as you answer, because the point here is to learn rather than to score.
- Mark an answer as a guess and it enters your review queue even if it happened to be right.
- Every answer moves your ability estimate for that topic and updates your readiness score.
- Retake as often as you like.
Sample questions
Which type of propagation follows the curvature of the Earth and works best at lower frequencies?
- Sky wave
- Ground wave
- Line-of-sight
- Tropospheric ducting
Why Ground wave is right: Ground wave travels along the Earth's surface and is strongest at LF and MF. Absorption increases sharply with frequency, so ground wave range shrinks as you move up the spectrum.
VHF and UHF communication is normally described as which kind of propagation?
- Skip
- Ground wave over hundreds of kilometres
- Line-of-sight, slightly beyond the visual horizon
- Ionospheric refraction
Why Line-of-sight, slightly beyond the visua… is right: At VHF and above, signals travel essentially in straight lines. Atmospheric refraction bends them slightly downward, so the radio horizon is about 15% further than the visual horizon.
Raising a VHF antenna higher above ground primarily improves communication because it:
- increases the transmitter power
- extends the radio horizon
- lowers the SWR
- changes the polarisation
Why extends the radio horizon is right: At VHF the limiting factor is the horizon, which depends on antenna height. Height is usually a bigger win than extra transmit power.