Design of Circularly Polarized Filtering Array Antenna with Two Radiation Nulls

In this paper, a quasi-cascaded triplet (CT) cross-coupled second-order perturbation circularly polarized filtering array antenna (CPFAA) is proposed. A simple microstrip patch antenna is used as a radiated resonator, and quasi-third-order cross-coupling topology is utilized with a coupled band-rejected resonator, which introduces two radiating nulls with high frequency selectivity and realizes circular polarization with better integration performance. The reflection coefficient of the proposed antenna is less than -10dB from 3.24GHz to 3.62GHz. The effective bandwidth range of the circular polarization of the antenna is 3.43-3.57GHz.This antenna achieves high-efficiency left-handed circularly polarized radiation function within the effective bandwidth.