half wave antennas don't need a ground element/plane/vehicle body to work . 5/8 aka .64's have been used without them also but the work better with some sort of counterpoise . 1/4 wave antennas shorter need some sort of counterpoise unless they are designed to use the coax as a ground element . the rod of god was a half wave antenna with tapped coil for tuning . very similar to the old ringo antennas that used a tapped loop for tuning . beams antennas FWIU work best with a reflector and one or more directors and the reflector and director(s) have to EACH be a certain lenmgth and distance apart according to the band it's used on . the performance difference with a full length 1/4 wave (9ft on CB) would be similar to a antron 99 over the 1/4 wave .