Published on 10/13/2026
A designer connects a 20 W transmitter to a 10 cm RG316 jumper at 2.4 GHz and the PTFE jacket smells hot after an hour. Meanwhile a ham pushes 100 W through RG58 at 14 MHz for years without a problem. Cable power handling is not a single number. It depends on frequency, temperature and mismatch.
Short answer: RG58 handles roughly 200 W at 100 MHz and about 55 W at 1 GHz, RG316 about half of those, and LMR-400 class cable several hundred watts at 1 GHz. All values are typical average-power ratings at 25 C and a matched load, and they fall quickly as frequency and temperature rise.
This guide explains why, shows typical figures and gives a quick method to derate for your own conditions.
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Average power is limited by heating. The cable loses power as heat along its length, and the dielectric and jacket have a maximum temperature. Figures below are approximate, from typical manufacturer data at 25 C ambient, matched load, still air. Check the exact datasheet for your cable.
| Cable | 100 MHz | 400 MHz | 1 GHz | 2.4 GHz |
|---|---|---|---|---|
| RG58 (PE dielectric) | 200 W | 90 W | 55 W | 30 W |
| RG316 (PTFE) | 150 W | 70 W | 40 W | 25 W |
| RG213 (PE) | 700 W | 330 W | 200 W | 110 W |
| LMR-400 class | 1,300 W | 700 W | 400 W | 250 W |
Key idea: Power rating falls roughly with the square root of frequency, because loss rises that way and heat is what sets the limit.
Limit 01
Conductor and dielectric heating
Loss turns RF into heat. Small cable has little surface to shed it.
Limit 02
Dielectric temperature
PE softens near 80 C. PTFE tolerates 200 C, which is why RG316 beats RG58 in hot spots despite its size.
Limit 03
Peak voltage breakdown
Pulsed or high-VSWR signals can arc. Peak power limit is much higher than average, but it depends on pulse width.
Limit 04
Connector limits
SMA and BNC connectors limit before the cable at high power. N type handles far more.
Let us size the assembly
Send frequency, average power, VSWR and ambient temperature. We will recommend cable and connectors, and sweep the finished assembly on a VNA.
Talk to an Engineer| Condition | Derating guide |
|---|---|
| Ambient 50 C instead of 25 C | Cut rating by about 30 to 40 percent (PE cable) |
| VSWR 2:1 on the line | Cut rating by about 20 to 30 percent |
| Cable bundled with others or in conduit | Cut by another 20 to 40 percent |
| Altitude above 3,000 m | Cut peak power; heat shedding is worse |
| Sunlight and outdoor heat | Cut by 20 percent or more |
As a quick guide: for under 10 W up to 6 GHz, RG316 is fine. For up to 50 W at VHF and UHF, RG58 or RG400 work. Above 100 W, use RG213, LMR-400 class or larger cable, and N or 7/16 DIN connectors. Our cable selection guide has the full tree.
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What is the power handling of RG58?
About 200 W at 100 MHz, 90 W at 400 MHz and 55 W at 1 GHz, at 25 C and matched load.
How much power can RG316 handle?
Roughly 150 W at 100 MHz, 70 W at 400 MHz and 40 W at 1 GHz. PTFE gives it better temperature tolerance than RG58.
What is the power rating of LMR-400?
Typical average power ratings are about 1.3 kW at 100 MHz and around 400 W at 1 GHz.
Does VSWR reduce power handling?
Yes. High VSWR creates hot spots in the cable and cuts safe power by 20 to 30 percent at 2:1.
Why does power rating drop with frequency?
Loss rises with frequency, so more power turns into heat in the same length of cable.
Is average or peak power more important?
Average power for heating and peak power for breakdown. Check both for pulsed systems.
Treat cable power ratings as frequency-dependent and derate for heat and mismatch. When in doubt, pick one cable size up.
SigmaRF builds RG58, RG316, RG213 and low-loss assemblies in India (Vadodara) and the USA (Cleveland area), swept on a VNA before shipment, with lead times as short as 2 days.
Need an assembly for higher power?
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