Sub-THz Circularly Polarized Horn Antenna Using Wire Electrical Discharge Machining for 6G Wireless Communications

Abstract

A novel compact high-efficient circularly polarized conical horn antenna is realized with Wire Electrical Discharge Machining (EDM) technique operating at 300 GHz for 6G wireless communications is presented. The proposed antenna structure consists of three main components; a waveguide feed, a circular polarizer disk, and a conical horn. The waveguide feed is a standard WR-03 rectangular waveguide which feeds the whole structure. The circular polarizer disk is comprised of a crossed slot with unequal lengths which are perpendicular to each other. By adjusting the lengths of both slots, two orthogonal modes are excited in the antenna to produce circular polarization. The conical horn is mounted on the circular polarizer disk. The proposed antenna was designed and optimized using CST Microwave Studio and is validated experimentally by an inexpensive direct Wire-cutting EDM technique over the WM-860 frequency band. The fabricated circularly polarized horn antenna achieved a wide impedance bandwidth of 20 % from 270 GHz to 330 GHz with a reflection coefficient ≤ -15 dB. The measured results show that the 3 dB axial ratio of the fabricated antenna prototype has a bandwidth of 7 GHz from 309 GHz to 316 GHz with a minimum axial ratio of 1.15 dB at 312 GHz. The measured normalized radiation patterns show good agreement with simulated results for different frequencies in both the elevation and azimuth planes at broadside direction with good symmetry in both planes.