Motorola Corporation

John G Doggett, Jr

Monty W Bai

Hugh Robert Malone

Keith A Kingston

Ronald P Vidano

Earl R Yingling

The present invention provides two approaches for eliminating a keyhole problem associated with an azimuth-elevation gimbal antenna which is a problem that occurs when the antennae is tracking a satellite vehicle that is substantially directly overhead, i.e., the satellite vehicle is near the zenith position. At such a point, the azimuth motor of the gimbal antenna must turn very rapidly when the satellite passes through such near zenith position. A first approach involves tilting up one of the elevation axis joints when the antenna points at or near its zenith position such that the pointing angle may be altered by a predetermined angle, for example around 0.5&deg; to 1&deg;, from the zenith position. A second approach involves tilting the secondary reflector of the cassegrain antenna such that the pointing direction of the antenna may be altered by a predetermined angle.

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Chandler, AZ, United States of America

John G Doggett, Jr