Ground plane effects on quadrifilar helix antenna phase center and radiation characteristics for GPS applications

Resonant quadrifilar helixes (QHs) have found applications in Global Positioning System (GPS) receiving antennas. Results of an investigation of QH antennas with shaped ground planes and their effects on the radiation pattern, input impedance, and phase center stability are presented. It is necessary to know the location of the phase center of the field radiated to a great precision in an application like GPS. The phase center has been determined by two methods: the tangent sphere technique and an optimization technique that minimizes the mean square error.<
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