Basic Qualification · B-006 Feedlines and antenna systems · B-006-013-009
Quelle est la longueur approximative du fil pour une boucle horizontale syntonisée à 7,15 MHz?
- A41,96 mètres
- B10,49 mètres
- C20,00 mètres
- D42,80 mètres
Correct answer: D — 42,80 mètres. Question tirée de la banque officielle d'ISDE.
Why
A full-wave horizontal loop at 7.15 MHz needs a wire length calculated by dividing the speed of light by the frequency, then multiplying by a factor of about 0.95 to account for how radio waves travel slower in wire than in empty space. 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