Basic Qualification · B-006 Feedlines and antenna systems · B-006-012-009
Si vous deviez régler une antenne dipôle demi-onde pour qu'elle résonne à 3,75 MHz, quelle en serait la longueur approximative?
- A40,00 mètres
- B62,40 mètres
- C80,00 mètres
- D38,13 mètres
Correct answer: D — 38,13 mètres. Question tirée de la banque officielle d'ISDE.
Why
A half-wave dipole for 3.75 MHz is roughly 38.13 metres because radio waves travel slightly slower in wire than in free space, shortening the required length from the theoretical 40 metres. 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