Recently we were contacted by a farmer, based just outside of the city of Lincoln, Lincolnshire.
He had had a system supplied and installed by another company a few years ago, however performance had decreased over time.
The first task was to carry out an audit of the installed equipment. This included performance tests of the installed radios to verify that the correct power output was being achieved from each radio. We also checked on air speech quality, and receive audio.
Once we were satisfied that the equipment was working properly (there is no point fitting a new aerial to a vehicle with a bust radio), we checked the aerial systems for forward and reflected power. This is done with a SWR (standing wave ratio) meter.
A number of the aerials fitted to the tractors and combine harvesters were in a poor state. Some whips were missing / damaged, while others were simply the wrong length.
The length of the aerial will vary depending on the frequency that the radio operates on.
The farmer had bought a replacement magmount aerial from a high street supplier, however these come ‘un-trimmed’. Therefore some of the power was being reflected back into the radio, and not going out into the ether (as it should).
After trimming to the correct length, the output power increased. They also reduce the risk of radio equipment damage.