Tri-band GPS antenna with low-multipath ground plane

A single feed circularly polarized antenna is proposed for the GPS application. It is composed of four substrates. The bottom layer of the antenna is a single-fed four-port hybrid ring in order to provide the required equal amplitudes and 90° phase shift signals for circular polarization. The other three substrates, each has a square patch to achieve the tri-band performance. The simulated results show that the antenna can cover all GPS bands (L1L2L5), which has a 24MHz bandwidth at each operating frequency. It has good impedance matching characteristics in the (1.17-1.6) GHz band. Because of the susceptibility to low-angle multipath, two kinds of ground plane are presented. We compare the performance of the two proposed antennas which have low-multipath ground plane. Our results show that both configurations, when properly optimized, are good candidates for modernized GPS antenna.