Basic Qualification · B-006 Feedlines and antenna systems · B-006-011-003
What is the approximate length of the director element of a Yagi antenna for 21.1 MHz?
- A 3.38 metres
- B 3.55 metres
- C 6.44 metres
- D 7.11 metres
Correct answer: C — 6.44 metres. From the official ISED question bank, verified word for word.
Why
A Yagi antenna's director element is slightly shorter than a half-wave dipole, but the official answer key for this specific question bank lists 6.44 metres as the correct length for 21.1 MHz. The full explanation — and one for every question — is in Pro.
Practise this section
Getting the signal out: antennas, feedlines, SWR, baluns, matching, and why antenna length depends on frequency.