Most so-called No Ground Plane antennas use the coax shield and the radio as an accidental ground plane. I'd love to see someone sell a CB version of the ham-style end-fed half wave antenna with a step-up transformer and a ferrite-bead balun to keep RF off the radio.
The basic setup is to make the whip a half wavelength, rather than the usual quarter wavelength. Mostly it's done by winding twice as much wire onto a fiberglass core as for a quarter-wave whip. The feedpoint impedance at one end of a half wave radiator is really high, like 600 ohms or more. The NGP coax is cut to an exact length that makes it a step-up transformer. But it does this by NOT connecting the coax shield at the antenna end. This will keep the SWR under control, but makes the coax shield into an accidental radiating element. Try to run any real power and you'll be getting RF burns from the mike, or signal-rectification "squeal" problems.
Never have taken a Shakespeare marine CB antenna apart. Always figured that they use the same trick, just can't say first hand.
Still makes me wonder, if you took a ham step-up transformer meant for an end-fed half wave wire and used it at the feedpoint of a CB NGP whip would it really fix the "hot RF" problem on the radio and coax.
73
