Antennas are the most important part of a CB radio and they require a flawless tuning procedure. A properly tuned antenna will promise interference free music, however a poorly tuned antenna will give a bad performance. Antenna tuning is the process where its length is adjusted so that it can match with the radio frequency. The efficiency of an antenna is measures through standing wave ratio, also known as SWR. Tuning with the help of a SWR requires you to achieve the lowest possible reading. You can have guaranteed radio efficiency if your antenna is tuned properly.
What is SWR?
Standard wave ratio is the measure of the power signals given out by the radio through the antenna into the atmosphere. This is why setting up the antenna is very important. There should be a thorough checking of the power being emitted by radio into the atmosphere by the SWR whenever new CB or antenna is installed. There will be less range of transmission by a poorly functional antenna and this might potentially cause damage to the internal parts of the radio. A short coax cable is used to join the antenna with the SWR meter.
A higher reading on SWR indicated poorly transmitted signals through the antenna. The higher the reading goes the poorer will the antenna work. Incase if higher readings, you might be using the wrong type of antenna or the length has not been properly adjusted. If you require the best advisable performance, you need to adjust the settings on the SWR as well. It should either be tuned to the lowest channel or to the highest channel. It is better to check the signal transmission with both. This will ensure optimum performance by the radio under all conditions. If the reading shows 1.0, this means that 100% of the radios power signals are being transmitted. In case of 2.0, it means that only a half of the power is being transmitted and for 3.0 it means that only third of the power is being given off.
The first step for tuning the CB antenna is to go to an open place. It is better to be in a place where there are no interferences or other vehicles etc. and make sure all the doors and windows are closed. Disconnect the antenna from the coax cable and turn the CB off. Take the antenna coax cable and connect it to the SWR meter (it will be labeled).then connect the short coax jumper cable from the transmitter position to the back of CB. Then turn the CB on and select channel 1. Set the SWR meter on the forward position and then make the SWR indicate set position by keying the microphone. Change the SWR meter to the reflect position and talk in the microphone. Take the reading shown on the SWR meter. Repeat the same steps with Chanel 40 and match the readings.
In case of a higher reading on Chanel 1 as compared to 40, the antenna is too short. Similarly, if the reading on channel 40 is higher than the one on Chanel 1, then your antenna is very long. You should shorten it.
After achieving an acceptable SWR reading, you can remove the meter and continue with the daily processions. This is one time process and it is worth your while. It ensures a flawless radio time, and promises no interferences. All the adjustments should be made with small changes and hopefully the radio will work like a champion! I hope you have a good car ride with the radio.