Basic Qualification · B-006 Feedlines and antenna systems · B-006-012-003
What is the three-dimensional radiation pattern of a half-wavelength dipole in free space?
- A Major lobes at 45-degree angles to the antenna
- B A torus (donut shape) around the antenna
- C A major lobe off each end of the antenna
- D Spherical (equal radiation in all directions)
Correct answer: B — A torus (donut shape) around the antenna. From the official ISED question bank, verified word for word.
Why
A half-wavelength dipole radiates strongest in a circle around its middle, with almost no signal coming off the ends, creating a shape like a donut or torus in three dimensions. 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.