Basic Qualification · B-006 Feedlines and antenna systems · B-006-002-011
What kind of transmission line has two conductors maintained side by side, a constant distance apart, using insulated spreaders?
- A Twin-lead
- B Twisted pair
- C Open-wire line
- D Coaxial cable
Correct answer: C — Open-wire line. From the official ISED question bank, verified word for word.
Why
Open-wire line fits the description because it uses two separate wires held a fixed distance apart by insulating spacers, often called spreaders, which keep them from touching while allowing air to act as the main insulator. 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.