Why is SWR Important?
Following on from the series of posts I have been doing about getting set up on CB Radio I have talked a lot about SWR and why it is important to tune your aerial to your CB Radio in order to get the best from the radio and to prevent possible damage to either yourself or your equipment.
Now in no way should I be considered an expert and I am only relaying what I have learnt in the most basic of terms and would direct you to someone with a much better understanding of radio should you require more than the most rudimental knowledge of SWR.
SWR Stands for 'Standing Wave Ratio' and is to do with the wave form when you put power into an aerial which is obviously what happens when you transmit a signal on a radio.
The basics of it is that there is current running down the coaxial from your CB or HAM Radio. This runs along the length of the cable and IS emitted from the length of the aerial.so that the radio waves come out of the aerial.
A big part of a successful radio transmission is to keep as much of the power which is being transmitted by the radio is delivered out of the aerial during a transmission. Part of that and this is where the theory around standing wave ratio comes in to it is when it reaches the end of the aerial it is reflected back on itself so there is a kind of return wave back from the aerial.to the CB Radio at least if the SWR on the aerial is high.
What that is doing then is passing power back to the CB Radio which can be dangerous. It can burn out the internal components of your CB Radio and will also result in very poor performance in terms of transmitted range since the reflected power isn't being properly emitted from the aerial. What needs to happen with SWR is that the amount of power returned to the radio is minimised.
The quality and design of the coaxial cable which connects the CB Radio to the aerial is also important. Obviously the job of the coaxial cable is to deliver the power to the aerial as efficiently as possible and it is designed in such a way to deliver all of the power possible without loss of leakage from the cable itself.
Any poor connections or shorts on the cable connections can effect the SWR of a set up enormously and could create dangerous conditions if used to transmit with such a problem. Problems can also occur if you run higher wattage through the use of an amplifier as this would push higher amounts of power to the aerial and with a high swr would reflect back higher amounts of power back to the radio possibly causing devastating effects.
So this is why we do take the time to set up an aerial properly not just for performance but for the protection of the equipment and no less ourselves. If you are thinking about 'running a burner' and you have high swr it could really damage your equipment.
A standard legal CB Radio transmits at 4Watts but if you are running say a 100 Watt burner and if perhaps 10% of that power is reflected back into the CB Radio I'm pretty sure that could do some damage to the cb radio itself.
Its important then to get your SWR as low as possible before adding any sort of amplifier and you really should consider if you really need to be pushing extra watts especially at the risk of interference to others and ultimately the enjoyment of other radio users.
Any poor connections or shorts on the cable connections can effect the SWR of a set up enormously and could create dangerous conditions if used to transmit with such a problem. Problems can also occur if you run higher wattage through the use of an amplifier as this would push higher amounts of power to the aerial and with a high swr would reflect back higher amounts of power back to the radio possibly causing devastating effects.
So this is why we do take the time to set up an aerial properly not just for performance but for the protection of the equipment and no less ourselves. If you are thinking about 'running a burner' and you have high swr it could really damage your equipment.
A standard legal CB Radio transmits at 4Watts but if you are running say a 100 Watt burner and if perhaps 10% of that power is reflected back into the CB Radio I'm pretty sure that could do some damage to the cb radio itself.
Its important then to get your SWR as low as possible before adding any sort of amplifier and you really should consider if you really need to be pushing extra watts especially at the risk of interference to others and ultimately the enjoyment of other radio users.
YouTube Video
Why is SWR Important?
Other Posts
Setting the SWR on the CB in the carCB Car Set up
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