Total posts : 45366
Mobile radio install, regardless of frequency..
Coax shield comes loose at the radio. No or poor range. RF is thrown everywhere inside the vehicle. Light bar goes off, siren goes nuts, lights in the dash flash, all kinds of crazy stuff. Retighten the connector at the radio, problems go away..
No earth ground involved. There is a d.c. path to the radio and antenna but that doesn’t matter. We’re dealing with RF..
A magnet mount antenna. No physical connection to ground at the antenna end but is coupled to body ground through capacitance. Same issues if the shield was removed at the source..
The coax is a circuit of its own and needs proper impedance at both ends to contain the RF inside of the shield. If this is achieved, the coax is just a pipe to send RF power to a radiator. The more that it is unbalanced, the more RF it emits from the shield.. (V.S.W.R.)