A microstrip circular patch antenna with two shorting pins is proposed as an antenna with reduced surface wave and lateral wave excitation. Theoretical analysis of the cavity modes of the patch lead to a design procedure for the antenna. Simulation results using the IE3D-Zeland software support the theory and verify the reduced surface wave capability. By using four shorting pins instead of two, we demonstrate the possibility of achieving circular polarization with high polarization purity in

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... dition to the reduced surface wave. It is demonstrated that a discrimination against the lateral wave of 30 dB or more is achievable. Applications include design of large patch arrays with reduced coupling and GPS receiving antennas that reduce low angle interfering signals.