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A Buyer’s Guide to Custom RF Cable Assemblies: RG316 vs. LMR400
A Buyer’s Guide to Custom RF Cable Assemblies: RG316 vs. LMR400
In any RF system, the antenna often gets all the glory. However, the connection between your radio module and that antenna—the RF cable assembly https://www.e-commtech.com/RF-Cable-Assembly.html—is just as critical. A poor-quality cable or the wrong choice of cable type can lead to significant signal loss, turning a high-performance system into a mediocre one.
At E-COMM Technology, we specialize in custom RF cable assemblies. Two of the most common cables requested by our clients are RG316 and LMR400. While both serve the same fundamental purpose, they are worlds apart in terms of performance and application.
This guide will help you understand which cable is right for your project.
1. The Basics: What is Signal Loss (Attenuation)?
Before diving into specific cables, it’s important to understand attenuation. As an RF signal travels through a copper cable, it loses energy due to resistance and dielectric losses. This is measured in decibels (dB) per foot or meter.The frequency of your signal also matters: the higher the frequency, the higher the loss. A cable that works well for a 433MHz LoRa sensor might be completely unusable for a 5.8GHz Wi-Fi 6 router.
2. RG316: The Flexible Internal Workhorse
RG316 is a high-temperature, flexible miniature coaxial cable. It features a silver-coated copper-clad steel inner conductor and a PTFE (Teflon) dielectric.* Best For: Internal wiring within devices, short pigtails, and applications where space is extremely limited.
* Pros:
* High Flexibility: Can be routed through tight corners inside a small IoT enclosure.
* Heat Resistance: PTFE dielectric allows it to withstand high soldering temperatures and harsh industrial environments.
* Size: Very thin (approx. 2.5mm diameter).
* Cons:
* High Loss: It has relatively high attenuation compared to thicker cables. It is generally not recommended for runs longer than 1–2 meters in high-frequency applications.
3. LMR400: The Low-Loss Outdoor Powerhouse
LMR400 is a significantly thicker, high-performance coaxial cable designed to replace older, high-loss cables like RG8. It features a solid copper-clad aluminum center conductor and a foam polyethylene dielectric.* Best For: Long outdoor runs, base station installations, and connecting outdoor antennas to indoor gateways.
* Pros:
* Ultra-Low Loss: Designed specifically to minimize signal attenuation over long distances.
* Durability: Features a robust PE jacket, making it suitable for outdoor UV exposure and direct burial.
* Performance: Maintains signal integrity even at high frequencies (up to 6GHz).
* Cons:
* Rigidity: It is thick (approx. 10mm diameter) and stiff, making it difficult to route inside small spaces.
* Weight: Much heavier than RG316.
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