A GNSS Antenna With a Polarization Selective Surface for the Mitigation of Low-Angle Multipath Interference

Abstract

This paper presents a nonresonant polarization selective surface (PSS) to address the problem of multipath distortion in global navigation satellite system (GNSS) antennas. The study of the radiated fields of a circular patch antenna reveals that surface wave (SW) radiation on the edges is not the major source of a high axial ratio (AR) at grazing angles, which opposes presently accepted theory. It is shown that the AR problem originates in the different θ dependence of the intrinsic field components E <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">θ</sub> and E <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">φ</sub> . The use of a three-layer-tapered FSS in close proximity to the patch modifies Eθ and results in an acceptable AR for angles close to 90°. An AR better than 2 dB is achieved at angles beyond the horizon (θ = 90°) and in all planes at the GPS L1 frequency band (f = 1.575 GHz). This solution outperforms the techniques in literature in terms of profile, diameter, performance, and simplicity.