A Low-Multipath Wideband GPS Antenna With Cutoff or Non-Cutoff Corrugated Ground Plane

Abstract

We compare the performance of the classic global positioning system (GPS) choke ring ground plane with a new shallower design. Both the choke ring and the new ground plane are here designed to operate uniformly between 1.15 GHz and 1.60 GHz while maintaining the required low-multipath performance in the whole bandwidth. To achieve reception in this wide range of frequencies, the radiating element chosen is a droopy bowtie turnstile. A classic choke ring is composed of deep concentric rings on a flat circular metal ground plane. We have modeled the choke ring as a metal corrugated surface of depth d such that lambda/4lesdleslambda/2 , operating at cutoff: the multipath suppression (i.e., the proper RHCP/LHCP pattern shaping) is obtained by eliminating the surface wave on the ground plane in a certain frequency band. When shallower concentric rings of depth dleslambda/4 are used, the corrugated surface operates at non-cutoff: the required multipath rejection can be achieved by cancellation (destructive interference) rather than suppression of surface waves. The comparisons performed in this study include theory, numerical simulations, and hardware tests. Our results show that both configurations, when properly optimized, are good candidates for reception of modernized GPS, GLONASS, and GALILEO satellite signals from GPS permanent stations.