Basic Qualification · B-006 Feedlines and antenna systems · B-006-008-001
A wire dipole has a resonant frequency of 3900 kHz. How can you change its resonant frequency to 3600 kHz?
- A Make it longer
- B Make it shorter
- C Install it as a sloper
- D Use smaller diameter wire
Correct answer: A — Make it longer. From the official ISED question bank, verified word for word.
Why
Lowering a dipole's resonant frequency requires increasing its physical length because a longer wire naturally vibrates at a slower rate, much like a longer guitar string produces a deeper note. 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.