Larsen Electronics, Inc.

L James Larsen

David M Phemister

The present invention is a moisture-insensitive system adapted to couple radio frequency energy at a low impedance from a matched two conductor transmission line, through a vehicle windshield and to an antenna in a manner which minimizes stray radio frequency radiation within the passenger compartment of the vehicle. The system includes two pair of conducting plates, one pair mounted on each side of the windshield, each pair opposite the other pair. A coaxial feed line is coupled to the inside pair of plates and a matching circuit is connected across the outside pair of plates. A full-size, unloaded antenna element is connected to the output of the matching circuit. A decoupling device, such as a decoupling sleeve or a RF choke, can be used to minimize RF current flow on the shield conductor of the coaxial feed line. The coaxial cable is coupled directly through the windshield, without an intervening matching network, so that RF energy at a low impedance is coupled to the outside pair of plates. This low impedance minimizes parasitic coupling of the feed system to moisture on the windshield, windshield wipers and other foreign bodies. The elements of the invention cooperate to minimize the level of stray radiation within the passenger compartment of the vehicle and provide, in the illustrated embodiment, a 2.0:1 VSWR bandwidth that extends from 830 to 880 megahertz.

Mobile antenna and through-the-glass impedance matched feed system

An antenna mount for a vehicle includes an insulated base with an internally threaded sleeve defining a central opening in the base. A blind-type clamping assembly threads into the sleeve for anchoring the base to a body panel of a vehicle. The clamping assembly includes a clamp member with a threaded stud and integral oblong clamping flange at the lower end of the stud. A stud nut threaded internally and externally threads onto the stud and into the sleeve for joining the clamping assembly to the base. The stud joins the flange at a position offset from the geometric center of the flange toward one of its ends to subdivide the flange into two flange portions of unequal length so as to facilitate entry of the flange through a smaller than usual installation hole in the vehicle body panel and subsequent clamping of the flange against the underside of the panel through progressive threading of the stud nut into the base. Lead-in conductor cable passages are provided through the clamping assembly and base, and the stud nut and stud provide an anchor for the cable within the base.

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Vancouver, WA, United States of America

L James Larsen