Conical Horn Antenna with High Gain and Circular Polarization for Sub-mm-Wave/Terahertz

This letter proposes a simple and compact circularly polarized (CP) conical horn antenna structure for sub-millimeter/THz band (75 − 110 GHz) applications. The proposed horn antenna is fabricated by a computer numerical control (CNC) milling technique approach to streamline the manufacturing process and increase the accuracy and the reduce time-consuming fabrication process. The horn antenna has a measured |S₁₁ |< − 10 dB bandwidth that matches the W-band frequency range of 75 − 110 GHz (37.8%), whereas the CP feature operates within the 3 dB axial ratio (AR) bandwidth of 95.9 − 104.4 GHz (8.5%) and beyond this range is the active region of the linearly polarized (LP) feature and high right-hand CP (RHCP) gain that exceeds 24.2 dBic on the CP bandwidth. In addition, the antenna has a low sidelobe level (SLL < − 24 dB) and high aperture efficiency (> 70%) on the CP bandwidth. Experimental results of the proposed horn antenna demonstrate excellent gain and CP performance outcomes and are in good agreement with the simulation results. Therefore, the proposed horn antenna can be a reasonable candidate for the Sub-millimeter-wave and future 6G applications used in high-speed wireless and space communication systems.