A Millimeter-Wave (V-Band) Dual-Circular-Polarized Horn Antenna Based on an Inbuilt Monogroove Polarizer

In this letter, a high-performance dual circularly polarized (CP) circular waveguide horn antenna operating in the V-band (54-60 GHz) is analyzed, built, and tested. The antenna is designed from a cylindrical waveguide section and consists of two mutually orthogonal side-fed ports, a mono-groove, and a conical horn section. The mono-groove is an annulus sector placed at 45° with respect to both the input ports and provides a phase delay of 90° to generate right-hand circular polarization (RHCP) and left-hand circular polarization (LHCP). Simulation results show that the proposed CP horn antenna has interport isolation more than 15 dB, axial ratio (AR) below 2.2 dB, and polarization isolation over 25 dB in the impedance matching bandwidth from 54 to 60 GHz. Also, the proposed antenna provides symmetric radiation patterns. A prototype of this antenna has been fabricated using computer numerical control (CNC) machining technique. The experimental results show good agreement with the simulation results.