Generally they don't work very well as a counterpoise. A friend of mine
bought a new Lumina APV, plastic van, several years ago. He had owned it for
3 years and got his ham ticket. He rushed out to the local Ham Store and
bought a magnetic mount 2m antenna. Of course he was shocked when it just
fell over! He had no idea his van was made of plastic.
For HF, the larger the vehicle, the better the system radiates. The vehicle
is actually part of the antenna system. A car with a bumper mounted HF whip
acts like an L shapped radiator fed at some point along the L, the car being
the lower half of the L. The whip radiates at a low, vertical angle while
the car radiates mostly straight up resulting in rather high angle pattern.
Putting the whip in the center of the car results in less radiation from the
car and lower horizontal angles.
About all you can do is bond what metal parts of the car you can find with
some copper braid and hope tune the antenna as best you can.
Not being familiar with mobiling, how can you make a good
>antenna mount with the all fiberglas bodies and bumpers.
>Is it wise to use a trailer hitch as a mount if it is welded to the frame?
>I am getting ready to start mobiling.
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