A Low-Profile Circularly Polarized Magnetoelectric Dipole Array Based on Micrometal Additive Manufacturing for Sub-THz Applications

A low-profile wideband circularly polarized (CP) magnetoelectric (ME) dipole antenna is proposed based on micrometal additive manufacturing (M-MAM) technology for sub-THz applications. The CP ME dipole antenna is composed of four planar patches with a metal strip connecting the diagonal patches, four L-shaped vertical walls, and a slotted cavity which is used to enhance boresight gain and axial ratio (AR) bandwidth. A rectangular microcoaxial line (RMCL) feeding cavity is newly designed to excite the antenna via a coupling slot on the ground. By further employing the proposed antenna as radiating elements and combining a corporate RMCL feed network with an integrated RMCL-waveguide transition, a $4\times 4$ low-profile wideband antenna array is designed and fabricated based on the M-MAM technology. The measurement results of the fabricated prototype show that the array has an operating bandwidth ( $\vert S_{11}\vert \lt -10$ dB, AR < 3 dB) from 139 to 170 GHz, and boresight gain varying from 18.6 to 20.5 dBi are achieved in the operating band. The measurement and simulation results have good agreements.