Basic Qualification · B-006 Feedlines and antenna systems · B-006-008-003
Quelle est la longueur d'onde en espace libre ("free space") d'un signal de 25 MHz?
- A12 mètres
- B19 mètres
- C39 mètres
- D6 mètres
Correct answer: A — 12 mètres. Question tirée de la banque officielle d'ISDE.
Why
A 25 MHz signal has a wavelength of 12 metres because radio waves travel at the speed of light, which is roughly 300 million metres per second. The full explanation — and one for every question — is in Pro.
Practise this section
Feedlines and antenna systems is section B-006 of the Basic exam: Getting the signal out: antennas, feedlines, SWR, baluns, matching, and why antenna length depends on frequency.
Drill B-006 — free, no account