Also known as: coax, coaxial cable, feedline

Coaxial cable (“coax”) carries RF between the antenna and receiver. A centre conductor runs inside a tubular shield, separated by a dielectric, which keeps the signal contained and the impedance constant (commonly 50 Ω).¹ Every metre and every connector adds loss — and the loss grows with frequency.

Coax carries RF on a centre conductor inside a shield; keep runs short and quality high to limit loss.

Overview

A long or low-grade cable can quietly undo a good antenna, so operators keep feedline short or mount a low-noise amplifier at the antenna. A poor match also raises SWR.

Sources

1. Coaxial cable — Wikipedia, on coax construction, characteristic impedance, and frequency-dependent loss. ↩

See also

• Attenuation
• Path loss
• Antenna
• Standing wave ratio (SWR)
• Low-noise amplifier (LNA)

Learn it step by step

• Antennas 101