Basic Qualification · B-006 Feedlines and antenna systems · B-006-012-001
Si vous construisez une antenne dipôle demi-onde syntonisée à 28,150 MHz, quelle en sera la longueur approximative?
- A2,53 mètres
- B5,08 mètres
- C5,33 mètres
- D10,66 mètres
Correct answer: B — 5,08 mètres. Question tirée de la banque officielle d'ISDE.
Why
At 28.150 MHz, a half-wavelength dipole is roughly 5.08 metres long because radio waves travel at the speed of light, and dividing that speed by the frequency gives the full wavelength, which is then halved for this antenna type. 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