A Wideband Crossed Dipole Filtering Antenna With Circular Polarization

This letter presents a broadband circularly polarized filtering antenna with a parasitic square loop and four U-shaped elements. The antenna incorporates slotted branches on the dipole arms to enhance impedance matching and improve the axial ratio bandwidth for circular polarization (CP). The parasitic square loop creates a radiation null in the low-frequency range, whereas the use of four U-shaped parasitic branches improves high-frequency filtering characteristics. Simulation results reveal the antenna achieves a −10 dB impedance bandwidth of 46.1% (1.67 ~ 2.67 GHz) and a 3 dB axial ratio(AR) bandwidth of 82% (1.32 ~ 3.12 GHz). The antenna also demonstrates significant out-of-band suppression, exceeding 16 dB at the lower band and 24.7 dB at the upper band, with a peak gain of 7.88 dBi within the band. The antenna exhibits excellent circular polarization and filtering performance, making it ideally suited for satellite communication applications.