Basic Qualification · B-006 Feedlines and antenna systems · B-006-012-004
What is the impedance at the feed point of a half-wave dipole in free space?
- A52 ohms
- B300 ohms
- C450 ohms
- D73 ohms
Correct answer: D — 73 ohms. From the official ISED question bank, verified word for word.
Why
A half-wave dipole in free space naturally presents a resistance of about 73 ohms at its feed point, which is the specific value your exam expects. 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