Space-efficient vertical choke rings for geodetic-grade multipath mitigation in GNSS antennas

Abstract We present a novel design for a miniaturized choke ring structure, optimized for operation in the L5/E5a and L1/E1 frequency bands (1.176 and 1.575 GHz). The choke rings are vertically stacked and enable to achieve geodetic-grade multipath suppression while minimizing the planar footprint of the antenna. The measured performance of an antenna on the proposed choke rings (20 cm diameter) in the anechoic chamber has shown improved cross-polarization discrimination with front-to-back ratio > 22 dB. The developed structure is also compared to a canonical (horizontally stacked) choke ring structure and can achieve comparable or even better performance while having a significantly smaller footprint. This is also confirmed through GNSS field test results, where the residual multipath is obtained for the standalone antenna, the antenna on canonical choke rings and the antenna on the proposed choke rings, with clear improvements in terms of multipath suppression obtained with our proposed structure.