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Dual Band 144/440 Mhz J-Pole
It has been suggested that the performance of 70cm on the Dual Band J-Pole can be enhanced by creating a 6” coil of 6 wraps just below the antenna. We noticed no change in the performance of the antenna by doing so but if you have the slack cable it certainly wont hurt anything.
The following SWR was as tested. If you find your not getting satisfactory results the first place to check is your cable. You will need a dummy load to do this properly. Also you should make sure that you followed the Assembly directions carefuly. If there are any many metal structures near by, make sure that they are as far from the antenna as possible, including your mounting post. It needs to be no higher than the mounting bracket.