Basic Qualification · B-006 Feedlines and antenna systems · B-006-003-002
A common-mode current choke can be made by winding coaxial cable on a ferrite toroid. Why is cable with solid dielectric preferred over foam dielectric?
- A More flexible and easier to handle
- B More impedance to common-mode current
- C Less risk of a short due to centre conductor movement
- D Less impedance inserted in the signal path
Correct answer: C — Less risk of a short due to centre conductor movement. From the official ISED question bank, verified word for word.
Why
When you wind coaxial cable tightly around a ferrite toroid to stop unwanted currents, the cable bends sharply. 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.