Advanced Qualification · A-007 Feedlines and matching · A-007-005-004
On VHF/UHF frequencies, Doppler shift becomes of consequence on which type of communication?
- AContact via satellite
- BContact through a hilltop repeater
- CSimplex line-of-sight contact between hand-held transceivers
- DContact with terrestrial mobile stations
Correct answer: A — Contact via satellite. From the official ISED question bank, verified word for word.
Why
Satellites orbit Earth at high speeds, creating a rapid change in distance that shifts the radio frequency you hear, much like the pitch of a passing siren. The full explanation — and one for every question — is in Pro.
Practise this section
Feedlines and matching is section A-007 of the Advanced exam: Feedlines and matching at the advanced level: transmission line theory, impedance transformation, stubs and matching networks.
Drill A-007 — free, no account