Advanced Qualification · A-007 Feedlines and matching · A-007-007-009
L'impédance au centre d'un dipôle situé à plus de 3 longueurs d'onde au-dessus du sol est voisine de :
- A75 ohms
- B25 ohms
- C300 ohms
- D600 ohms
Correct answer: A — 75 ohms. Question tirée de la banque officielle d'ISDE.
Why
When a dipole antenna sits high above the ground, specifically more than three wavelengths up, the earth no longer influences its electrical behaviour. 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