A W-band Antenna with Dual Circular Polarization for mmWave Wireless Communications

This paper presents our study on a dual circular polarization feed horn for reflector antennas operating in W-Band. It mainly consists of a stepped septum polarizer, a circular horn and dual ports for LHCP and RHCP feeding respectively. Apart from the high gain that can be achieved when it is used together with parabolic reflector as a primary feed, it has the capability of transmitting and receiving two orthogonal circular polarized signal to achieve Polarization-Division Multiplexing (PDM) or a Full-Duplex in mmWave wireless communication systems. The simulation results show that the proposed feed horn can achieve 21% relative bandwidth from 85 GHz to 105 GHz with AR < 2 dB and reflection coefficient $\mathrm{S}_{11} <-15$ and isolation > 15 dB for both LHCP and RHCP. Radiation pattern with good rotational symmetry over the whole working bandwidth is also obtained in order to achieve high aperture efficiency when the feed horn works with a parabolic reflector.