The other day I needed some reliable communication at an event I was helping with. I decided to use some MURS radios that I had in my storage. We took four of them and they worked very well. I had them stored away and had kind of forgot how useful they were.
MURS stands for Multi User Radio Service. The FCC formally defines MURS as “a private, two-way, short distance voice or data communications service for personal or business activities of the general public”. MURS radios do not require a license to operate.
No MURS radio unit, may exceed 2 Watts transmitter power output. This is not the handicap it may seem, because unlike FRS (Family Radio Service), there are no antenna restrictions. Since MURS radio range is basically limited to line of sight, this lets you increase your range.
With MURS radios, you are allowed to use an elevated antenna with “gain” to increase your useful range. At VHF frequencies antenna height is more important than transmitter power. For two hand-held units on flat terrain, standing in the open without any obstructions, with both transceivers held at face level, the theoretical range is 5 miles (your line of sight). This is the best you can hope for without improved antennas.
If the transmitting station is at ground level, but the receiving antenna is elevated 25 feet above ground, theoretical your range approximately doubles to 11 miles. If the receiving station were standing on top of a 250-foot hill, the range would be about 20 miles. The highest point of any MURS antenna is not allowed to be more than 60 feet above the ground or 20 feet above the highest point of the structure on which it is mounted. Using a 6dB gain vertical antenna, at maximum legal height, fed with low loss coax such as LMR400 on your home base, and having a 3dB gain 5/8 wave mobile antenna whip mounted up high on the roof of your vehicle, with a good ground plane, you can work mobile-to-base simplex from 10-20 miles, depending upon terrain.
The five frequencies available in MURS radios:
- 151.820 MHz 11.25 KHz
- 151.880 MHz 11.25 KHz
- 151.940 MHz 11.25 KHz
- 154.570 MHz 20.0 KHz
- 154.600 MHz 20.0 KHz
An additional benefit of MURS radio frequencies are the PL codes (Private Line codes) which are sub-audible tones that allow users to operate on the same channel without hearing chatter directed to other users.
There are 38 PL codes available to each of the five MURS frequencies, which makes a combination of 190 different MURS channels. While this keeps you from hearing the transmissions of others, anyone operating without a PL can listen to you.
A comparison of MURS Radios versus FRS
- MURS permits four times more power (2 Watts instead the 0.500 Watts limit for FRS).
- MURS radio signals bend over hills better, but FRS signals are better at bouncing off surfaces and penetrating into buildings.
- MURS radio can be connected to an external antenna. FRS radios must employ a non-detachable antenna. For vehicle-to-vehicle operation with external roof-mount antennas, MURS can provide three to ten times the range of FRS radios.
The one problem with MURS radios for use in populated areas is that it is used by businesses like Walmart, who operate on channels 4 and 5 during business hours. In areas that are more rural, I have noticed very little use. In an emergency situation, most of the business radios would not be in use so MURS could provide you with good communications for short distances, up to several miles.