Antennas

From short to tall, Repco have a vast array of UHF radio antennas

Every ultra high frequency (UHF) radio needs an antenna. Even the handheld units have a stumpy UHF antenna so it can transmit and receive signals. The in-car units usually have one mounted to the outside of the vehicle. These come in different lengths and are rated in dBi (decibel relative to isotropic) or commonly called the gain of the antenna. The gain is the amount of power an antenna transmits in one direction compared to an isotropic radiator. Isotropic radiators broadcast signals in all directions at once.

UHF radio antennas that mount externally have mounts that make it easy to change from one antenna to another. The reason for this is UHF is a line of site communication medium. Some antennas work better in built up areas and hilly terrain, others work better on flat terrain. For instance, a 3dBi antenna is shorter and works better in built up and hilly terrain. A 6dBi antenna is a lot longer in length and being taller works well across open flat terrain. It has a greater range than a 3dBi antenna. To better explain there is a diagram below.

In the diagram Vehicle A & B have the shorter 3dBi antennas fitted and vehicles C & D have the taller 6dBi antennas fitted. Vehicles A & B can communicate as their antennas work best in a built-up environment. Same goes for vehicles C and D as it is open terrain and their bigger antennas have a greater range and there are very few obstacles. Vehicle communications between B & C may have been one sided. While B could transmit to C, C's transmissions will be blocked by the hills.

In the diagram Vehicle A & B have the shorter 3dBi antennas fitted and vehicles C & D have the taller 6dBi antennas fitted. Vehicles A & B can communicate as their antennas work best in a built-up environment. Same goes for vehicles C and D as it is open terrain and their bigger antennas have a greater range and there are very few obstacles. Vehicle communications between B & C may have been one sided. While B could transmit to C, C's transmissions will be blocked by the hills.

To effectively communicate C needed to have the right antenna. If they changed to a 3dBi then that would fix it. They could still talk to D provided D was within the shorter range of the 3dBi. This diagram helps explain where to use different UHF antennas though it is not always that cut and dried. Atmospherics where the signal can bounce off clouds, there may be gaps in built up areas or hills, how close you are to the people you are trying to contact can all make a difference.

Australia is a big place and if camping or driving in a group, UHF radios are a good way to communicate. Area's where mobile reception is poor is where a UHF device comes into its own. Repco stock a lot of good brands like GME and Uniden will have something to suit your budget. See our range of aerials and antenna's both online and in store. We have handheld or in-car UHF units to suit your application and if you are not sure our friendly store staff can assist you.