Abstract: A mobile antenna system for use at frequencies in and above the 800 MHz band having a collinear radiator mounted on one surface of a dielectric such as the window of a vehicle. A coupling system is affixed to a second surface of the dielectric. The coupling system includes a counterpoise for coupling RF energy between the radiator and a transmission line connected to a suitable transceiver. Decoupling members connected to the counterpoise minimize coupling of radio frequency energy to defogger wires on the window.