How to Choose a Wi-Fi Antenna Cable: A Complete Guide with Charts and Tests

Choosing the right cable for your Wi-Fi antenna is a task that directly affects the stability and speed of your wireless network. Even the most powerful antenna TP-Link Omada or Ubiquiti LiteBeam will show poor results if connected to the router via a low-quality or unsuitable cable. Signal loss in cheap cables can reach 30-50% on meters of length, nullifying all efforts to strengthen the coating.

In this article we will examine not only the technical characteristics (wave impedance, attenuation, shielding), but also practical tests of real cables in urban and suburban settings. You'll find out why. RG-58 only suitable for short connections, and LMR-400 It's capable of transmitting a signal over 30+ meters with virtually no loss. We'll also cover common installation errors that kill the signal more than any cheap cable.

1. Wi-Fi Antenna Cable Types: Comparison of RG, LMR, and AIRCOM

All coaxial cables for Wi-Fi are divided into three main groups, differing in design and areas of application. The choice between them depends on length of the route, frequency range (2.4 or 5 GHz) and operating conditions (outdoor/indoor).

• 🔹 RG series (RG-58, RG-213):Budget options with high attenuation. Suitable for indoor connections up to 5-7 meters. RG-58 loses up to 0.6 dB/m at 2.4 GHz, which is critical for powerful antennas.
• 🔹 LMR series (LMR-195, LMR-400, LMR-600):Professional low-attenuation cables. LMR-400 loses everything 0.22 dB/m at 2.4 GHz and is suitable for outdoor conditions.
• 🔹 AIRCOM+ (H-155, H-400):Ultra-low losses (up to 0.1 dB/m), but high price. They are used in commercial networks and for ultra-long-distance connections (50+ meters).

🔎 Which one to choose? For a home network with an antenna on the balcony (up to 10 m) it will be enough LMR-195For an outdoor antenna on a mast (15-30 m) - only LMR-400 or AIRCOM H-155. Cheap RG-58 It's only suitable for temporarily connecting a test antenna.

2. Wave impedance: 50 Ohm vs. 75 Ohm

One of the key parameters is wave resistance, measured in ohms (Ω). For Wi-Fi equipment, the de facto standard is 50 Ohm. 75 Ohm cables (for example, TV cables) RG-6) are absolutely not suitable: they cause impedance mismatch, which leads to:

• ⚡ Reflection of the signal back to the transmitter (degrades power)
• 📉 Connection speed drops by 30-70%
• 🔥 Overheating of amplifiers in high-power antennas (risk of failure)

⚠️ Attention: Some Chinese sellers are positioning RG-6 as "universal" for Wi-Fi. This is a marketing scam! This cable can only be used with special adapters 75→50 Ohm, which eat up to 10% of the signal.

3. Signal Attenuation: How to Calculate Losses

Attenuation (signal loss) is measured in decibels per meter (dB/m) and depends on:

1. Cable type (see table above)
2. Operating frequency (2.4 or 5 GHz)
3. Lengths of the route
4. Ambient temperatures (outdoor losses are higher in winter)

📊 Calculation formula:

Total loss (dB) = Attenuation (dB/m) x Length (m) x Frequency Factor

Example: For LMR-400 20 m long at 5 GHz frequency:

0.35 dB/m x 20 m x 1.3 (coefficient for 5 GHz) = 9.1 dB loss

⚠️ Attention: Losses over 10 dB make the connection unstable. If the calculation shows a value close to this, reduce the cable length or select a model with lower attenuation (e.g., AIRCOM H-400 instead of LMR-400).

Why does Wi-Fi work worse in winter?

At subzero temperatures, the copper in the cable contracts, increasing resistance. Condensation in the connectors also creates micro-shorts. Losses can increase by 15-20%!

4. Connectors and ports: which ones to choose for Wi-Fi

An equally important element is - connectors, which connect the cable to the antenna and router. A bad connector can add up to 3 dB loss (equivalent to 3 meters LMR-400!). For Wi-Fi equipment the following are used:

• 🔌 N-type (N-connector): The most reliable for outdoor antennas. Withstands high power and frequencies up to 11 GHz. Used in Ubiquiti, MikroTik.
• 🔌 SMA (RP-SMA): Compact connector for internal antennas. Note: RP-SMA (with a pin inside) and SMA (with hole) are not compatible!
• 🔌 TNC: Improved version of BNC, used in professional equipment.

🔧 Critical errors during crimping:

1. Insufficient screen cleaning → short circuit.
2. Pinched central conductor → signal break.
3. Lack of sealant on outdoor connectors → corrosion in 2-3 months.

The central core does not touch the screen|

The screen is tightly compressed with a metal sleeve|

The connector is fixed without any play|

Silicone sealant has been applied to the outdoor joints.

5. Shielding: How to protect yourself from interference

The quality of the shielding determines how resistant the cable is to external interference from other devices (microwaves, LTE towers, electrical wiring). The shielding level is indicated by letters:

• 🛡️ S (Single): One layer of foil. Suitable for short indoor runs only.
• 🛡️🛡️ SF (Single Foil + Braid): Foil + braid. Standard for LMR-400.
• 🛡️🛡️🛡️ SFF (Double Foil + Braid): Maximum protection for the outdoors.

📡 Practice test: In an apartment building, the cable is shielded SF showed a 20% more stable signal compared to S-version when working near an LTE tower. The difference is especially noticeable at the frequency 5 GHz, where the interference is stronger.

⚠️ Attention: Cheap cables often have "fake" shielding—the braid covers less than 60% of the cable's surface. You can check this by bending the cable: if the shield cracks, it's a counterfeit.

6. Outdoor installation: protection from weather and rodents

If the cable is laid outdoors (on a mast, along the facade of a house), it must withstand:

• 🌧️ Precipitation and UV radiation (shell made of PE or PVC)
• ❄️ Temperatures from -40°C to +80°C (standard for LMR-400)
• 🐭 Rodents (additional fiberglass armor)

🛠️ Installation tips:

1. Use cable ties in 50 cm increments to avoid sagging.
2. Install signs at the entrance to the building. oil seals for tightness.
3. To protect against lightning, ground metal masts and cable shields.

📌 Real case: After the winter of 2023, 30% of calls to service centers regarding “broken” Wi-Fi antennas were related to water ingress into connectors due to lack of sealingThe average repair cost 3-5 thousand rubles.

7. Common mistakes during selection and installation

Even experienced network administrators make mistakes that can ruin all their signal-boosting efforts. Here are the top 5:

1. 🔄 Using a TV cable (RG-6) for Wi-Fi. Losses at 5 GHz reach 1.2 dB/m - 5 times worse than LMR-400.
2. 📏 Cable laying under tensionThis leads to microcracks in the central core, increasing attenuation by 10-15%.
3. 🔌 Saving on connectorsCheap Chinese SMA connector for 50 rubles can add 2 dB loss.
4. 🌡️ Ignoring temperature conditionsCables without a frost-resistant sheath harden at -10°C, which leads to breaks.
5. 📡 Power mismatch. Powerful antennas (for example, Ubiquiti Rocket M5) require cables with a current reserve (not less than 1 A).

🔍 How to check the quality of installation? Use Wi-Fi analyzer (For example, NetSpot or inSSIDer) to measure the signal level to And after Replace the cable. A difference of 5-10 dBm will confirm the correctness of the choice.

FAQ: Answers to frequently asked questions

Can I use TV cable (RG-6) for a Wi-Fi antenna?

No, it is absolutely not recommended. RG-6 has a wave resistance 75 Ohm, while Wi-Fi equipment is designed for 50 OhmThis results in signal reflection and power losses of up to 50%. The exception is the use of special 75→50 Ohm adapters, but these also introduce additional losses (~1 dB).

What is the maximum length of a Wi-Fi antenna cable?

Depends on cable type and frequency:

• RG-58: up to 5 m (at 5 GHz - up to 3 m)
• LMR-195: up to 15 m
• LMR-400: up to 30 m
• AIRCOM H-155: up to 50 m

Above these values, losses exceed 10 dB, which makes the connection unstable.

Should the Wi-Fi antenna cable be grounded?

Yes, if the antenna is mounted outdoors on a metal mast. Grounding serves two functions:

1. 🌩️ Lightning protection (even if the antenna is not the highest point).
2. 📶 Reduces static electricity interference.

For grounding, use a copper wire with a cross-section of at least 2.5 mm², connected to the general grounding circuit of the building.

What is the difference between N-type and SMA connectors?

N-type:

• Large, reliable connector for outdoor antennas.
• Withstands power up to 500 W.
• Used in professional equipment (Ubiquiti, MikroTik).

SMA (RP-SMA):

• Compact connector for internal antennas.
• Maximum power: 50W.
• Attention: RP-SMA (with pin) and SMA (with hole) are not compatible!

How to check a cable for a break without special equipment?

Diagnostic methods:

1. 🔍 Visual inspection: Bends, cracks in the shell, oxidation of connectors.
2. 📱 Signal test: Connect the antenna directly to the router (without a cable) and measure the signal strength. Then connect the cable and repeat the measurement. A difference of more than 3 dBm indicates a problem.
3. 🔧 Testing with a multimeter: Set the tester to resistance test mode and measure the resistance between the center conductor and the shield at both ends. The value should be infinity (an open circuit or short circuit indicates a malfunction).