High-Performance GNSS Antennas with Phase-Reversal Quadrature Feeding Network and Parasitic Circular Array

摘要

The antenna is the first component in a positioning system, which processes the GNSS and correction signals received from multiple satellites. The precision of a position is strongly related to the performance of the GNSS antenna used. In this paper, several key antenna parameters are discussed with regard to high-precision applications. Two new technologies are proposed to solve the challenges encountered by the GNSS antenna design: ultra-wideband low-loss rotational sequential feed network using phase-reversal, and parasitic circular array loading technology. Based on these technologies, a new generation of high-performance GNSS antennas for ground based applications are proposed and validated by anechoic chamber measurement and live GNSS signal testing. Attributed to the outstanding wideband amplitude and phase balance performance of the antenna feed network, the proposed antenna covers the entire GNSS frequency spectrum with excellent gain and CNo. The antenna features very low axial-ratio and very small phase center variation from zenith to horizon. There is no phase center offset between high band and low band and the radiation patterns are highly symmetrical for which no antenna alignment is required with respect to its mounting direction. In addition, using the parasitic circular array loading (patent pending) technology along the peripheral of the radiation elements, the diffraction of surface waves at the edge of the antenna ground-plane is suppressed or re-radiated which results in further improved axial ratio especially at low-elevation angles. The gain roll-off at these angles is able to be optimized for a balanced lowelevation angle tracking and multipath rejection. Compared to conventional patch antennas, the proposed antenna uses a single PCB to achieve wide dual GNSS bands, maintains the planar and low-profile structure while allows for optimized gain roll-off and multipath performance.