Published on 10/13/2026 • Updated on 10/13/2026
A ham installs a 10 m RG58 run to a VHF antenna and wonders why the SWR meter looks fine but the signal is weak. Another engineer runs the same cable from a 2.4 GHz radio to a roof antenna and loses most of the power before it reaches the antenna. Same cable, same length, very different outcomes. Frequency decides almost everything.
Short answer: 10 meters of RG58 loses about 1.6 dB at 100 MHz, 3.7 dB at 400 MHz, 7 dB at 1 GHz and around 12 dB at 2.4 GHz. That last figure means only about 6 percent of your power arrives.
The table below gives dB per meter and total loss for 10 m so you can read your answer directly. The math and the common mistakes follow.
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Typical attenuation for solid-center RG58C/U with a polyethylene dielectric. Values are approximate and vary 10 to 20 percent between makers, with the cheapest tinned-braid cable at the high end.
| Frequency | dB per meter (approx.) | Loss over 10 m | Power remaining |
|---|---|---|---|
| 10 MHz | 0.05 | 0.5 dB | 89 % |
| 50 MHz | 0.11 | 1.1 dB | 78 % |
| 100 MHz | 0.16 | 1.6 dB | 69 % |
| 200 MHz | 0.24 | 2.4 dB | 58 % |
| 400 MHz | 0.37 | 3.7 dB | 43 % |
| 1 GHz | 0.72 | 7.2 dB | 19 % |
| 2.4 GHz | 1.2 | 12 dB | 6 % |
Key idea: Loss in dB adds linearly with length. If 10 m costs 3.7 dB at 400 MHz, 5 m costs 1.85 dB and 20 m costs 7.4 dB. Percent power does not add, dB does.
Take the dB per meter at your frequency, multiply by length in meters, then add connector loss. A BNC or N connector adds about 0.05 to 0.2 dB, and every extra adapter adds a little more.
For the full loss estimator, see our coax loss calculator guide and the attenuation chart in this series.
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Tell us the frequency and length. We will recommend a cable and build it, with every assembly swept on a VNA for VSWR and insertion loss.
Talk to an Engineer| Factor | Effect on 10 m loss |
|---|---|
| Frequency | Loss grows roughly with the square root of frequency |
| Cheap tinned or CCA braid | Adds 10 to 30 percent loss at VHF and above |
| Temperature | Loss rises about 0.1 percent per degree C over 20 C |
| Water in the cable | Can add several dB; replace damaged cable |
| Sharp bends below 5 x OD | Raises loss and VSWR |
| Stranded vs solid center | Stranded flexes better; loss is slightly higher |
RG58 is a 4.95 mm OD, 50 ohm cable with a velocity factor near 0.66. It is a good choice below 400 MHz and a poor choice at 2.4 GHz or above.
| Cable | Loss over 10 m at 1 GHz (approx.) | Tradeoff |
|---|---|---|
| RG58 | 7.2 dB | Highest loss of the group |
| RG213 | 4.5 dB | Thicker, 10.3 mm OD, harder to route |
| LMR-240 class | 3.9 dB | Good balance of size and loss |
| LMR-400 class | 2.2 dB | Best loss; 10.3 mm OD |
If you need flexibility and low loss at once, a custom assembly with the right cable family often beats using RG58 plus a preamp. The RF cable selection guide on this blog compares these.
Avoid these
How much signal loss does 10 meters of RG58 have?
About 1.6 dB at 100 MHz, 3.7 dB at 400 MHz, 7 dB at 1 GHz and 12 dB at 2.4 GHz. These are typical values for RG58C/U.
What is the loss of RG58 per meter?
Typical values are 0.16 dB/m at 100 MHz, 0.37 dB/m at 400 MHz and 0.72 dB/m at 1 GHz.
Is RG58 good enough for 2.4 GHz Wi-Fi?
Only for short runs under 1 m. At 10 m you lose about 12 dB, which is unacceptable for most links.
How many dB is half the power?
About 3 dB. 10 m of RG58 at 400 MHz is 3.7 dB, so you lose more than half the power.
RG58 or RG213 for a long run?
RG213 has about 40 percent less loss at the same frequency, but it is larger and stiffer.
Does RG58 loss change with temperature?
Slightly. Loss rises a little as the cable heats, and moisture ingress is a bigger threat than temperature.
Ten meters of RG58 is fine for HF and VHF, marginal at UHF and a poor choice above 1 GHz. Calculate in dB, include connectors, and move to a lower-loss cable when the number eats your link budget.
SigmaRF builds RG58, RG316, RG174 and low-loss assemblies from facilities in India (Vadodara) and the USA (Cleveland area), with every assembly VNA-swept before shipment and lead times as short as 2 days.
Need a cable made to length?
Send the frequency, length and connectors and we will quote the right cable.
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