High-Gain Dual Circularly Polarized Antenna for Air-to-Ground Wireless Link

This paper presents an E-band reflector antenna fed by dual circularly polarized feed system. Axial displaced ellipse reflector is adopted for high gain and low blockage mechanisms. The feed system mainly composed of orthomode transducer, iris polarizer and horn antenna, and possesses dual circular polarization. The orthomode transducer offers high isolation performance in broadband by double symmetry and the iris polarizer achieves phase shift by introducing discontinuities. In addition, the ridge and iris in the feed are optimized to be wide enough to fabricate and maintain good mechanical properties in higher frequency band. The entire antenna is simulated and fabricated. The measured gain of 45 +/- 1.2 dBi corresponds to about 52% efficiency. The measured results of reflection coefficients less than -18 dB, isolation over 27 dB, axial-ratio value less than 2.3 dB are achieved from 71 to 86 GHz.