Troubleshooting SWR Aerial Problems
What is SWR? - Standing Wave Ratio is matching an aerial to a radio.
If the SWR, measured on the highest channel, is worse than the SWR measured on the lowest channel, the aerial is too long. If the opposite is the case, the aerial is too short.
So, the procedure is as follows:-
If this figure is much too high at the extremes and OK on the middle channels, the aerial is too tightly tuned for your frequency range - try a different type of aerial.
If the SWR is too high on ALL channels, the possible causes are:-
On half wave and 5/8 wave aerials it is vital that the mounting pole does not protrude at all above the mounting bracket.
3" of the pole above the top of the bracket can produce a SWR of 2.5:1 which refuses to be affected by any amount of aerial adjustment.
Correctly carried out this operation is worth every minute of the time it takes, the benefits are less interference, greater range and longer life for your transmitter.