What vehicle do you have that you're worried about the ground plane? I have this same Comet antenna on my Ram 1500, and my wifes Wrangler, both with aluminum hoods. It's worked on my truck right out of the box. I can cover 2 meters, on up to our farm channels at 159 Mhz easily. Same with 70cm and GMRS. On the wife's Jeep it was a little more finicky. I trimed the botton section of the antenna to raise the resonant point on UHF to have coverage on 70cm, and GMRS. Doing this appeared to have no effect on VHF, or if it did, it didn't matter because it's so broadbanded, because I can still cover 144-159 and then some, easily.
N0GX changed their profile photo