Sub-THz U-Slot Coupled Stacked-Patch Radiating Elements for Dual-Polarized MIMO Array Antennas

Paper in proceeding, 2024

Several sub-THz (D-band, 136-148 GHz) dual-polarized array elements (unit cells, UCs) implemented in a multi-layer PCB technology are investigated in the infinite array environment. The elements are stacked-patch antennas with unbalanced aperture-coupled feeds (U-slots), having a slant 45 deg. polarization. We demonstrate that a baseline half-wavelength cavity-backed UC is capable of achieving ≤ 3.7 dB scan loss in the 60 deg. conical scan range and (132-149) GHz bandwidth. For the increased UC size, however, active polarization channel isolation drastically degrades and the element experiences scan blindness. To address this problem, a UC modification is introduced that suggests using a single-row mushroom-type electromagnetic band-gap structure along the UC sidewalls. Simulated results evidence the realized UC decoupling and elimination of the scan-blindness anomalies in the full visible scan range, with scan loss ≤ 4.2 dB in the 55 deg. conical scan range and (136-148) GHz bandwidth.