Basic Qualification · B-006 Feedlines and antenna systems · B-006-009-006
What is the approximate gain of a half-wave dipole in free space relative to an isotropic radiator?
- A 1.0 dB
- B 2.1 dB
- C 1.5 dB
- D 3.0 dB
Correct answer: B — 2.1 dB. From the official ISED question bank, verified word for word.
Why
A half-wave dipole concentrates radio energy slightly better in its favoured directions than an imaginary isotropic radiator, which radiates equally in all directions. 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.