Coax comparison

What to compare

Almost all amateur coax is 50 Ω. What differs is size, flexibility, construction and, above all, loss: the power that turns into heat in the cable instead of reaching the antenna. Loss rises with frequency and with length, and falls as the cable gets thicker. Pick the cable for your band and run, not by name.

Common types

Cable	Size (approx.)	Dielectric	Loss	Typical use
RG-174, RG-316	about 0.1 in	solid or PTFE	highest	Very short jumpers, portable work
RG-58	about 0.2 in	solid polyethylene	high	Short runs, HF, HT patch cables
RG-8X	about 0.24 in	foam	medium	Mobile and short HF runs
RG-213 (and RG-8)	about 0.4 in	solid polyethylene	low	HF stations, long-time standard
LMR-400, 9913 class	about 0.4 in	foam or air-spaced	lower	VHF/UHF, long runs, and anywhere loss hurts
Hardline	rigid or semi-rigid tube	foam or air	lowest	Towers and permanent installations; stiff and harder to terminate
RG-59, RG-6	about 0.25 in	foam or solid	n/a (75 Ω)	TV and video; not matched to 50 Ω ham gear

"LMR" and "9913" are brand and type names: other makers sell cables of similar construction. Foam or air-spaced dielectric lowers both loss and weight, and gives a higher velocity factor (about 0.8 versus 0.66 for solid polyethylene). See Feed line loss and velocity factor.

How much power arrives

Approximate loss for common cables, using rounded typical figures (about 5, 3.7, 2 and 1 dB per 100 ft at 100 MHz for the four rows below, scaled by the square root of frequency). Treat the numbers as estimates and use your cable's datasheet for real planning.

Cable	7 MHz	28 MHz	146 MHz	446 MHz
RG-58	1.3 dB	2.6 dB	6.0 dB	10.6 dB
RG-8X	1.0 dB	2.0 dB	4.5 dB	7.8 dB
RG-213	0.5 dB	1.1 dB	2.4 dB	4.2 dB
LMR-400 class	0.3 dB	0.5 dB	1.2 dB	2.1 dB

Loss per 100 ft, matched line. A 3 dB loss halves your power: with 100 W in, about 50 W reaches the antenna and about 50 W warms the cable. 6 dB leaves a quarter.

Choosing

• HF, short run: almost anything works. The loss at 7 to 14 MHz is small, and RG-213 or RG-8X is a comfortable choice.
• VHF and UHF: loss is large even over short runs. Use the biggest, lowest-loss cable you can: at 146 MHz, 100 ft of RG-58 wastes three quarters of your power.
• Power handling is limited by heating (more loss means more heat) and by the cable's voltage rating. Thin cables and high frequencies come first. The limit falls further with high SWR, because reflections raise current and voltage on the cable. See SWR and reflections.
• Connectors and flexibility matter: cable that flexes with a rotator must stay flexible, and every connector must suit the cable.
• Weather: use UV-resistant jacket cable outdoors and seal connectors: water ruins a cable. See RF connectors.

Related

• Coaxial cableConstruction, types and choosing a coax.
• Feed line loss and velocity factorAttenuation by frequency and electrical length.
• Characteristic impedanceWhat Z0 means and why it must match.
• SWR and reflectionsStanding waves, reflection coefficient and return loss.
• Open-wire and ladder lineLow-loss balanced feed lines.
• RF connectorsPL-259, N, BNC, SMA and when to use each.
• DecibelsThe logarithmic scale for gain, loss and signal strength.