Published on 7/21/2026 • Updated on 7/22/2026
Whether you're extending the antenna on a home Wi-Fi router, installing an outdoor access point, or building a long-range wireless bridge, choosing the right coaxial cable is just as important as selecting the antenna itself.
Many people invest in high-gain antennas expecting better wireless performance, only to discover that their signal strength barely improves. The culprit is often the coaxial cable. Every meter of cable introduces signal loss, and at Wi-Fi frequencies 2.4 GHz, 5 GHz, and now 6 GHz even a poor cable choice can negate the benefits of an expensive antenna.
This guide explores the different types of coaxial cables commonly used for Wi-Fi applications, compares their performance, explains why specific RG-series cables are preferred, and provides recommendations based on cable length, installation environment, and frequency.
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A coaxial cable carries high-frequency RF signals between the Wi-Fi router and its antenna. Unlike low-frequency electrical wiring, RF cables behave as transmission lines, meaning their electrical properties directly affect signal quality.
At Wi-Fi frequencies, signal attenuation becomes a significant factor. Every additional meter of cable reduces signal power before it reaches the antenna, and the amount of loss depends on:
Signal loss in coaxial cable is measured in decibels (dB). Every cable specification lists attenuation, usually expressed as dB per 100 feet or dB per 100 meters.
| Cable Loss | Power Reduction |
|---|---|
| 1 dB | Approximately 20% power reduction |
| 3 dB | Approximately 50% power reduction |
| 6 dB | Approximately 75% power reduction |
| 10 dB | Approximately 90% power reduction |
This illustrates why cable selection matters. If a router is connected to a high-gain antenna through a cable with excessive attenuation, much of the transmitted and received signal is lost before reaching the antenna.
Wi-Fi equipment including routers, access points, antennas, amplifiers, and connectors is designed around a 50-ohm impedance standard.
Using a 75-ohm cable, such as those intended for television or satellite systems, creates an impedance mismatch. This mismatch can cause:
RG174 is a thin, lightweight coaxial cable often found inside wireless devices and compact RF assemblies.
Characteristics
Typical Uses
Because of its high signal loss, RG174 should generally be limited to cable lengths of less than one meter in Wi-Fi applications.
RG316 is a premium alternative to RG174, featuring a silver-plated conductor and a PTFE dielectric.
Advantages:
Although RG316 offers improved performance, it still experiences relatively high attenuation at Wi-Fi frequencies, making it best suited for short jumper cables.
RG58 has been one of the most widely used RF cables for decades.
| Specification | Value |
|---|---|
| Impedance | 50-ohm |
| Diameter | ~5 mm |
| Construction | Flexible, affordable, widely available |
| Attenuation @ 2.4 GHz | ~30 dB per 100 m |
| Attenuation @ 5 GHz | Significantly higher |
Historically, RG58 was popular for amateur radio, two-way radio, test equipment, and early Wi-Fi installations. While acceptable for short indoor runs of one to three meters, it is no longer recommended for longer Wi-Fi installations.
RG142 is similar in size to RG58 but incorporates silver-plated conductors and PTFE insulation. Its advantages include better shielding, higher temperature tolerance, lower loss, and increased durability.
RG142 is often used in aerospace, defense, and RF testing, but its higher cost limits its use in consumer Wi-Fi installations.
RG400 is regarded as a professional-grade replacement for RG58. Features include:
It is commonly used in aviation, military systems, industrial wireless equipment, and laboratory testing. Although more expensive than RG58, RG400 offers noticeably lower attenuation and superior long-term reliability.
As cable lengths increase, low-loss coaxial cables become essential.
LMR195 is often selected for compact wireless equipment where flexibility is important.
Benefits
Typical Applications
Cable lengths up to 5–8 meters can generally be accommodated with acceptable losses.
LMR240 strikes an excellent balance between flexibility and low attenuation. It is widely used for outdoor Wi-Fi antennas, commercial wireless systems, enterprise access points, and industrial networking.
Advantages include:
Among professionals, LMR400 is often considered the benchmark for medium- and long-distance Wi-Fi antenna installations.
✓ What LMR400 Offers
Typical applications include:
LMR400's larger diameter (approximately 10 mm) makes it less flexible than smaller cables, but the reduction in signal loss is substantial.
When cable runs exceed 30–40 meters, LMR600 becomes an attractive option.
Advantages:
Because of its size and cost, it is generally reserved for commercial and industrial deployments.
Need a Wi-Fi Antenna Cable Assembly?
SigmaRF builds precision-tested coaxial cable assemblies in RG174, RG178, RG316, RG400, LMR195, LMR240, LMR400, and LMR600 — terminated with RP-SMA, SMA, N-Type, or TNC connectors to your exact length.
Get a Custom Assembly →The following table provides approximate attenuation values for common 50-ohm cables used in Wi-Fi installations. Actual figures vary by manufacturer.
| Cable Type | Diameter | Loss @ 2.4 GHz (dB/100 m) |
Relative Performance |
|---|---|---|---|
| RG174 | 2.8 mm | ~95 | Very Poor |
| RG316 | 2.5 mm | ~80 | Poor |
| RG58 | 5 mm | ~30 | Fair |
| RG400 | 5 mm | ~23 | Good |
| LMR195 | 4.9 mm | ~26 | Good |
| LMR240 | 6.1 mm | ~18 | Very Good |
| LMR400 | 10.3 mm | ~11 | Excellent |
| LMR600 | 14.9 mm | ~7 | Outstanding |
LMR400 has become the preferred choice for many Wi-Fi professionals because it balances performance, cost, and ease of installation. Its advantages include:
In many installations, upgrading from RG58 to LMR400 results in measurable improvements in received signal strength and overall link reliability.
The ideal cable depends on the distance between the router and antenna.
| Cable Length | Recommended Cables |
|---|---|
| Less than 1 meter | RG316, RG400, LMR195 |
| 1–5 meters | LMR195, LMR240, RG400 |
| 5–15 meters | LMR240, LMR400 |
| More than 15 meters | LMR400, LMR600 |
For indoor installations, flexibility and ease of routing are often the primary considerations. Cables such as RG400 or LMR240 are generally sufficient.
Outdoor installations require additional protection against:
Use cables with UV-resistant jackets and weatherproof all outdoor connectors using self-amalgamating tape or approved sealing methods to prevent water intrusion.
The performance of a coaxial cable depends not only on the cable itself but also on the quality of its connectors. Common Wi-Fi connector types include:
RP-SMA SMA N-Type TNC RP-TNC
Each connector should:
Using TV Coaxial Cable
Television coaxial cables such as RG6 or RG59 are designed for 75-ohm systems. Although adapters are available, they are not ideal for Wi-Fi equipment due to impedance mismatch.
Choosing the Cheapest Cable
Low-cost cables often use aluminum conductors, inferior shielding, or poor-quality dielectric materials, leading to higher losses and reduced durability.
Ignoring Frequency Ratings
A cable that performs adequately at 900 MHz may exhibit excessive attenuation at 5 GHz or 6 GHz. Always verify the manufacturer's specifications for your operating frequency.
Excessive Cable Length
Relocating the router or access point closer to the antenna is often more effective than adding several extra meters of coaxial cable. Shorter cable runs generally provide better performance than compensating with a higher-gain antenna.
The best cable depends on the application:
| Application | Recommended Cable |
|---|---|
| Internal router antenna | RG316 |
| Home Wi-Fi antenna (short run) | LMR195 |
| Outdoor home antenna | LMR240 |
| Enterprise Wi-Fi | LMR400 |
| Industrial wireless | LMR400 |
| Long-range point-to-point links | LMR400 or LMR600 |
| Temporary test setups | RG400 |
For most home and small business installations with cable runs longer than a few meters, LMR240 offers an excellent balance of flexibility and performance. For professional outdoor installations, LMR400 is widely regarded as the optimal choice because it minimizes signal loss while remaining practical to install.
Selecting the right coaxial cable is one of the most overlooked aspects of building a reliable Wi-Fi system. Even the highest-gain antenna cannot compensate for excessive losses introduced by an unsuitable cable.
For short connections inside equipment, cables such as RG316 or RG400 are appropriate due to their flexibility and compact size. As cable lengths increase, however, low-loss cables become essential. LMR240 is an excellent option for medium-length runs, while LMR400 has earned its reputation as the industry standard for professional Wi-Fi installations thanks to its low attenuation, superior shielding, weather resistance, and long-term reliability. For very long cable runs, LMR600 provides even lower losses, making it ideal for demanding commercial and industrial deployments.
Wi-Fi Cable Assemblies from SigmaRF
Precision-tested coaxial cable assemblies in RG316, RG400, LMR195, LMR240, LMR400, and LMR600 terminated with RP-SMA, SMA, N-Type, TNC, and RP-TNC connectors for Wi-Fi, IoT, and industrial wireless installations.
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