A low loss coaxial cable is often used when an RF signal needs to travel through a longer cable run or work at a higher frequency without losing too much strength along the way. But choosing the right cable is not only about picking a thicker model or choosing a well known cable series. You still need to check the system impedance, operating frequency, cable length, connector type, shielding structure, and installation environment.
What Is a Low Loss Coaxial Cable?
A low loss coaxial cable is an RF coaxial cable designed to reduce signal attenuation during transmission. It keeps more signal strength over the cable run than a standard coaxial cable, especially when the system uses a longer feeder line or works at higher frequencies. In a coaxial structure, the centre conductor carries the signal, the dielectric controls electrical behaviour, the shield helps reduce external interference, and the jacket protects the cable from mechanical and environmental stress.
The word “low loss” should not be judged by cable name alone. A low attenuation coaxial cable is affected by conductor size, dielectric material, shielding structure, impedance, operating frequency, cable length, and installation environment. For example, one common 50 ohm low loss cable uses a foam polyethylene dielectric, aluminium tape, tinned copper braid, and a 10.29 mm jacket diameter, with shielding effectiveness above 90 dB.
Low loss coaxial cable is mainly selected when the RF path cannot tolerate excessive attenuation. Typical examples include antenna feeder lines, wireless communication equipment, GPS receivers, WLAN devices, telecom equipment, RF modules, and test systems. In these uses, the cable length, operating frequency, shielding quality, and connector interface should be checked together, because each part of the transmission path can affect the final signal level.
Match the Impedance First
Before comparing cable diameter, jacket material, or price, check the coaxial cable impedance. The cable, connector, and equipment port should use the same impedance so the RF signal can pass through the full path with less reflection.
A 50 ohm coaxial cable is normally selected for RF communication, wireless systems, radio equipment, GPS devices, test equipment, and antenna systems. A 75 ohm coaxial cable is normally selected for TV antenna, cable television, video distribution, broadcast equipment, and high bandwidth video systems. Some connector families are available in both 50 ohm and 75 ohm versions, so the connector body shape alone is not enough to confirm impedance.
Mixing 50 ohm and 75 ohm parts may not stop the system immediately, but it can create impedance mismatch. The result may include higher VSWR, extra insertion loss, reflected signal, or unstable performance at higher frequencies. For a low loss coaxial cable, this should be checked early because a cable with good attenuation data can still perform poorly if the impedance does not match the rest of the RF path.
Check Loss at Your Frequency
Do not judge a low loss RF cable only by the words “low loss” in the product name. The first number to check is attenuation. It is usually shown as dB per 100 ft or dB per 100 m, and it must be read at the same frequency your system will use. Cable loss at 150 MHz and cable loss at 2.4 GHz are not the same value, even when the cable model is the same.
A simple example makes this clearer. One common 50 ohm low loss coaxial cable has about 1.5 dB loss per 100 ft at 150 MHz, about 3.9 dB per 100 ft at 900 MHz, about 6.0 dB per 100 ft at 2,000 MHz, and about 10.8 dB per 100 ft at 5,800 MHz. The cable has not changed, but the frequency has. That is why the attenuation chart matters more than a general product label.
Cable length then decides the total insertion loss. If the attenuation is 6.0 dB per 100 ft at the required frequency, a 50 ft run is about 3.0 dB before connector loss, while a 200 ft run is about 12.0 dB before connector loss. For antenna feeders, telecom jumper cable, RF cable assemblies, and test setups, this number should be checked before choosing the cable size or connector type.
Choose the Cable Size for the Run
Cable diameter should match the cable run length and the space available for routing. A thinner flexible coaxial cable is easier to install in short indoor jumpers, compact devices, cabinets, and test connections. RG58, LMR 200, and LMR 240 type cables are often considered when the run is short and the routing space is limited. For example, one LMR 240 class cable has a jacket diameter of 0.240 in, which is about 6.10 mm, and an installation bend radius of 0.75 in, which is about 19.1 mm.
For a longer antenna feeder, wireless equipment link, or telecom jumper cable, a larger low loss coaxial cable may be a better fit. LMR 400 and RG213 type cables are common choices for medium cable run length where lower coaxial cable loss is needed. One LMR 400 class cable has a jacket diameter of 0.405 in, which is about 10.29 mm, and an installation bend radius of 1.00 in, which is about 25.4 mm. It gives lower loss than smaller cable types, but it also needs more space around corners, panels, and connector entry points.
For long run coaxial cable, do not choose the largest cable only by its loss value. A bigger cable can reduce attenuation, but it can also make routing harder and may require larger connectors, stronger strain relief, wider cable trays, and a larger bend radius.
Cable Types and Typical Uses
| Cable Type | Better Fit | Selection Notes |
|---|---|---|
| RG58 | Short RF links, cabinet wiring, test leads, compact equipment | A flexible 50 ohm coaxial cable with a smaller diameter. It is easy to route, but coaxial cable loss is higher than larger low loss RF cable types. |
| RG213 | Medium length RF connections, radio systems, antenna feeder sections | A 50 ohm coaxial cable with a larger diameter than RG58. It is more suitable when the cable run needs lower loss than thin flexible cable can provide. |
| LMR 200 and LMR 240 | Short to medium antenna jumpers, GPS, WLAN, mobile antennas, small wireless equipment | These cable types offer a balance between flexibility and lower attenuation. LMR 240 is often considered when routing space is limited but RG58 loss is too high. |
| LMR 400 | Antenna feeders, wireless systems, base station jumpers, coaxial jumper cable | A common low loss coaxial cable for 50 ohm RF signal transmission, especially when the run is longer than a short equipment jumper. |
| LMR 600 or larger | Long run coaxial cable, tower feeders, lower attenuation RF paths | Larger cable can reduce loss over distance, but it needs more routing space, a larger bend radius, and compatible connectors. |
| RG6 and RG11 | TV antenna, cable television, satellite, video distribution, long 75 ohm runs | These are usually 75 ohm coaxial cable types. They should not be used as direct replacements for 50 ohm RF cable assemblies unless the whole system is designed for 75 ohm impedance. |
RG58 and LMR 400 are often compared because they represent two different selection directions. RG58 is easier to handle in short and compact connections, while LMR 400 is more suitable when the cable run is longer and lower attenuation is required. RG6 and RG11 follow a similar size logic in 75 ohm systems, with RG11 usually selected for longer runs where lower signal loss is needed.
Check Shielding and Jacket
A low loss coaxial cable still needs the right shielding and jacket. The shield controls RF interference and EMI, while the jacket decides how well the cable fits the installation environment. A cable used inside a cabinet does not face the same conditions as an outdoor coaxial cable on a rooftop, tower, or exposed antenna route.
For shielding, common structures include braided shield, foil shield, or a combined shield structure. A simple braid can keep the cable flexible, while foil plus braid usually gives better coverage against outside interference when the cable is routed near power cables, wireless modules, switching equipment, or other RF signal paths.
For the jacket, the choice usually comes down to where the cable will be installed. PVC jacket is common for indoor RF cable assemblies and short equipment jumpers. PE jacket is more suitable for outdoor coaxial cable because it handles moisture, sunlight, and weather exposure better. For buried or wet routes, the cable may also need water resistant construction and sealed connector ends.
FAQ
Conclusion
Choosing a low loss coaxial cable should come down to the whole signal path, not just the cable name. Impedance, attenuation at the working frequency, cable length, diameter, shielding, jacket material, and connector match all need to be checked together before placing an order. For antenna feeders, wireless equipment, telecom jumpers, GPS systems, or RF cable assemblies, a small mismatch in cable type or connector selection can affect the final signal level.