Abstract: A UHF mobile radio communications antenna that may be mounted on a vehicle window without drilling into or damaging the surface of the vehicle. An exterior part includes an antenna element and a resonant coupling circuit, and may be removably mounted to the exterior of the vehicle window. An interior part includes a resonant coupling circuit and a ground counterpoise, and may be removably mounted to the interior of the same window and positioned in alignment with the exterior part. The exterior and interior parts are in radio frequency communication by electromagnetic coupling therebetween. The interior part functions additionally as a radio frequency ground counterpoise independent of any vehicle metal. The interior part is adapted for connection to a mobile radio transceiver by coaxial cable. No post installation tuning of the invention is required and, thus, the invention may be easily installed without special skills.