A Wideband Circularly Polarized Patch Antenna Using λ/4 and λ/2 Resonators

摘要

A wideband circularly polarized (CP) patch antenna with enhanced axial ratio (AR) bandwidth via codesign of feeding network is proposed in this paper. One λ/4 resonator and one λ/2 resonator are introduced and coupled in proximity to two orthogonal points of a square patch radiator to excite two orthogonal modes. These two resonators not only function as impedance matching elements to achieve equal magnitude of two orthogonal modes in a wide frequency band, but also provide the required 90° phase difference. In this way, two minima in the AR response appear, resulting in extended AR bandwidth. Simulated results demonstrate that 2% 3-dB AR bandwidth is achieved on a low profile of 0.014 λ₀.