Design of a Compact BeiDou Navigation Filtering Antenna Based on Parasitic Branches

This paper presents a compact filtering patch antenna that achieves filtering characteristics by loading parasitic branches on the antenna feeding probe. It is able to achieve a radiation null at both low and high frequencies, with the two radiation nulls independently controllable and adjustable in position. Additionally, unequal-sized circular loops loaded on the radiating patch enable right-hand circular polarization radiation characteristics, while ensuring that the antenna’s circular polarization characteristics remain independent of its filtering response. This innovative filtering antenna has potential applications in satellite navigation systems for reducing interference between different frequency bands, thereby enabling anti-interference communication for navigation antennas.