Back in the days of OMEGA, some of us would bring along portable GPS receivers just for fun, or to cross check OMEGA accuracy. We would attach the antenna with a suction cup on the rear side window which had no electric heating elements and therefore wouldn't interfere with reception. It worked great, and without affecting other navigation or radio equipment. For "external" power (to save batteries) we'd plug into a 28 VDC light bulb socket. Needless to say, we couldn't and wouldn't use our personal GPS units for primary navigation, although they were more accurate than the OMEGA units.
