Basic Qualification · B-006 Feedlines and antenna systems · B-006-010-006
What is an advantage of downward sloping radials on a ground plane antenna?
- A It brings the feed point impedance closer to 300 ohms
- B It lowers the radiation angle
- C It brings the feed point impedance closer in to 50 ohms
- D It increases the radiation angle
Correct answer: C — It brings the feed point impedance closer in to 50 ohms. From the official ISED question bank, verified word for word.
Why
Lowering the radials on a ground plane antenna changes how the antenna interacts with the transmitter, moving the electrical resistance at the connection point from a high value toward the standard 50 ohms used by most Canadian amateur radio equipment. 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.