I just bought a CB antenna from a local truck stop. The antenna is actually designed to go on an 18-wheeler I think, but I found a magnetic mount for it. I know that the antenna is supposed to be mounted onto the roof of a car because it uses the car as a ground-plane, but I had to mount mine on my bumper because it was just too high up on the roof of my car. How bad will this hurt my reception? Is there any way to make some soft of artificial ground-plane out of my bumper? It's not a metal bumper, but I guess I could put some type of sheet metal or something over it..?