How it works

Cable loss is the datasheet attenuation at your frequency times the length: dB = dB per 100 m × metres ÷ 100. Connector losses you enter are added on top. The power at the far end is P × 10^−dB/10, so 3 dB leaves half the power and 10 dB a tenth: 3 dB on 5 W leaves 2.51 W.

The figures come from each maker's own datasheet, as printed.2 3 4 5 6 7 8 9 10 11 12 13 Between two printed frequencies the box draws a straight line on log–log axes, the way loss curves run; outside the printed range it does not guess, and you can type the loss from your own cable's sheet instead. Belden prints dB per 100 ft, converted here at 3.28084 ft to the metre.

The result is for a matched line: a high SWR adds loss on top. On receive the cable takes the same number of dB from the incoming signal. “RG-58” is a family name: two RG-58 cables from different makers can differ by a few dB per 100 m, so the box names the exact product.

Antenna lengths for your frequency: dipole antenna calculator.

Sources

Show all 13 sources

Cable	Diameter	dB per 100 m	Loss over your length	Power out	Datasheet covers
Times LMR-600	14.99 mm	3.2	0.47 dB	4.48 W	30–8000 MHz
SSB Ecoflex 15	14.6 mm	3.4	0.51 dB	4.44 W	5–6000 MHz
SSB Ecoflex 10	10.2 mm	4.7	0.70 dB	4.25 W	5–6000 MHz
Messi & Paoloni Hyperflex 10	10.3 mm	4.7	0.71 dB	4.25 W	1.8–10000 MHz
Times LMR-400	10.29 mm	4.9	0.74 dB	4.22 W	30–8000 MHz
SSB Aircell 7	7.3 mm	7.3	1.09 dB	3.89 W	5–6000 MHz
RG-213 · Belden 8267	10.3 mm	7.6	1.13 dB	3.85 W	1–4000 MHz
Times LMR-240	6.1 mm	9.8	1.46 dB	3.57 W	30–8000 MHz
RG-8X · Belden 9258	6.15 mm	12.5	1.87 dB	3.25 W	1–1000 MHz
Times LMR-195	4.95 mm	14.4	2.16 dB	3.04 W	30–8000 MHz
RG-58 · Belden 8240	4.9 mm	15.4	2.31 dB	2.94 W	1–1000 MHz
RG-174 · Belden 8216	2.79 mm	34.2	5.14 dB	1.53 W	1–1000 MHz

Coax loss calculator

Every cable at 146 MHz over 15 m, 5 W in

How it works

Sources

Every cable at 146 MHz over 15 m, 5 W in

How it works

Sources

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