Microstrip Patch Antenna for GPS application

A low profile patch antenna for GPS application is here proposed and analyzed. The radiating structure consists on a square patch with 8 slits introduced on each side and on the corners to reduce the overall dimensions. The circular polarization is obtained by quadrature feeding the patch with two pins placed symmetrically on the two main axis. The 90° phase shift is obtained by a 90° microstrip hybrid junction integrated on the back side of the antenna ground plane. The proposed patch antenna is suitable for implementing low cost, high stable and well circular polarized GPS antenna, as demonstrated by numerical simulations and experimental results. 1 INTRODUCTION Nowadays patch antennas with high permittivity sintered material substrates are used for GPS automotive application. These very compact antennas are quite expensive and enough prone to circular polarization degradation due to the positioning of the antenna on the car body, as a rule near the scattering edge of the metallic roof. The aim of this paper is to realize a robust circular polarization antenna for GPS application using lowcost microstrip substrates where the low noise amplifier (LNA) may be easily integrated. Section 2 describes the GPS microstrip patch antenna design and simulation results, while section 3 presents the results of measurements performed on the antenna