to get a correct swr reading your antenna must be grounded.
but sad way to much plastic and that hurts.
also where on your truck/car/rig/etc matters. as the body does influence how you can transmit and receive.
the duel trucker deal has a reason. must be 8-9 feet apart. and gives you a bis toward the front and rear of your rig.
place in the center of your car roof and you get a almost perfect circle.
in a perfect world your mobil antenna should be grounded at its base.
and your radio should be grounded..not just the power ground.
both + and - feed lines should be direct from your battery. and both fused.
way too much line interference from computers (in your car/truck/etc) to just gain your power from a quick source.
http://www.amazon.com/The-ARRL-Antenna-Book-Transmission/dp/0872599876
http://store.cq-amateur-radio.com/Detail.bok?no=183
here is a start.
sorry this site will not allow me to post links. only as text.
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