Antenna Cable

Choosing the best Coaxial cable for your Wireless system

If you have ever set up an a wireless microphone or in ear system you have probably run into a frustrating truth: your wireless system is only as good as the cable connecting it. You can buy the most expensive high-gain antenna on the market, but if you run the wrong coaxial cable, your signal will vanish your transceiver.

The most common cable that ships with your wireless system would be RG58. This is a 50ohm coaxial cable that is very flexible and at short distances has minimal loss perfect for distances under 25’ its easy to deploy and budget friendly but what if you need something longer what should you be using.

There are several low loss cables on the markets today. In the mid-20th century as a U.S. military standard, RG-213/U is a robust 50-ohm coaxial cable. It was specifically designed to standardize and replace earlier World War II-era cables like the RG-8/U, shifting the impedance to an exact 50.0 ohms to support advanced, precise RF (Radio Frequency) communication systems. Belden developed the 9913 low-loss 50-ohm coaxial cable in the early to mid-1980s. It was originally engineered as an indoor cable that was more flexible than the RG-213 and GR-8. Then in 1993 Times Microwave Systems developed the LMR 400

These are all great options for permeant installations but what If you are a touring engineer and need to deploy your antennas every day, dealing with a stiff soled core cable may be difficult. Times Microwave Systems developed the LMR-400 UltraFlex (UF) they added a stranded core and a rubber thermoplastic Elastomer jacket (TPE) to make it the as flexible as possible for the size of cable.

The Belden 9913 is a great option but In the RF world, LMR-400uf is widely considered the gold standard for long-distance, high-frequency antenna connections. But is it always the right choice for your specific project? Let’s look into that.

If RG-58 is the what most every system is shipped with and LMR400 is the Gold Standard what is the middle option. That would be RG8x or the Times Microwave Systems version of it LMR240. These cables are almost identical, the LMR240 has a little better specs but the RG8x is more flexible and user friendly for deploying it every day.

Now that we know a little about the cables what is the best for my application.

Lets look at the 3 most popular cables.                    

Altho LMR-400uf is the most flexible low loss cable but out of Theas 3 options it will be the stiffest largest cable. RG-8x will be easier to deal with and RG58 will be the lightest essayist to wrap up and deploy every day

As a rule of thumb in wireless design, when your total cable loss approaches or exceeds  6db you need to consider active system changes (like applying gain) to recover the signal. Ideally, you want to maintain unity gain(offsetting loss perfectly without over-amplifying noise).

As cable diameter increases, signal loss decreases. However, thicker cables are heavier, more expensive, and harder to coil. Look at how the average loss accumulates over distance at a standard operating frequency (e.g., 400mhz to 600mhz)

Signal Loss by Cable Length

Cable Type	25 Feet	30 Feet	50 Feet	100 Feet
LMR-400uf	0.9 db	1.0 db	2.75 db	3.6 db
RG-8X	2.0 db	2.5 db	4.75 db	8.5 db
RG-58	3.0 db	3.5 db	6.8 db	10.0 db

You’ll notice at the sorter lengths you only have 1-2db of loss but as the length increases you see greater losses in the RG-58 and the RG-8x

How to Choose the Right Cable for Your Setup

In a receiving system like your wireless microphones if you are under 25’ RG-58 and RG-8x are Bothe great options but if your going to go over 25’ the RG-8x becomes a much better option to maintain your RF gain without adding amplifiers. When you get to around 50’ the LMR400 is really your best option.  When looking at an RF receiver and the loss of signal over distance you are often making that up by getting the antennas closer to the source so you often don’t seed the effect of the cable.

When it comes to In Ear systems that loss can be very detrimental because you have less signal at the receiver.  It’s important to have as little loss as possible when transmitting so the belt-pack receiver your being worn on stage has be best clean signal. Because of this we always recommend the LMR400. If your cable length is under 30’ the RG8x is the next best choice. You will have a little loss but it is easier to set up and deal with the cable. Your system will work with RG58 but we do not recommend going over 25’.

We hope this helps you make our decision on what cable to use. OCD-Labs stocks several sizes of LMR-400 and RG-8x but can build custom sizes and looms as needed. Please contact us at INFO@OCD-Labs.com