Design of a Wide-Band IBFD Circularly Polarized Antenna

A wideband in-band full-duplex dual circularly polarized antenna is designed for millimeter wave wireless communication. The proposed antenna combines two mirror-symmetric wideband circularly polarized antenna elements. The proposed antenna element comprises a round-cut square patch etched with an L-shaped slot and a round-cut square parasitic patch. The parasitic patches are used to broaden the operating bandwidth, and the L-shaped slot can improve the circular polarization performance of the proposed antenna. The simulated results show that the proposed antenna can operate between 24.6 and 28.8GHz (15.5%). The isolation of the proposed antenna is higher than 20 dB in the operating band, and the maximum isolation is 33.8 dB. The proposed antenna radiates a right-hand circularly polarized wave and a left-hand circularly polarized wave when exciting port 1 and port 2, respectively. The axial ratio bandwidth is 26.5-28.8GHz at the excitation of port 1, and 26.6-28.7GHz at the excitation of port 2. The maximum gain of port 1 and port 2 are 7 dB and 8.1dB, respectively.