Shaping the axial-ratio footprint of crossed-dipole antennas

Abstract

Abstract-A method is proposed to adaptively change the axial-ratio beam of simple circularly-polarized antennas. It is shown, that by varying the phase shift between two orthogonal elements the axial-ratio beam shape can be dynamically adjusted. This allows control of the direction of minimum axial-ratio and the ability to increase or decrease the beamwidth in one of two planes. The method is intended for satellite navigation systems: it can improve the rejection of reflected signals in varying propagation conditions (e.g. urban canyons), while using simple and low-cost circularly-polarized antennas.

Reconfigurable Axial Ratio in Compact GNSS Antennas

“…This is however true only for boresight radiation and was not deeply studied in the literature. The only exception is [15] where some early theoretical studies (without experimental validation) are presented for two idealized dipoles. By using the proposed method, one can synthesize an adaptive AR pattern, which can provide an AR ≤ 1 dB within a 83° beamwidth.…”