W‐Band High‐Efficiency Low‐Profile Four‐Folded Transmitarray Antenna Based on Dual‐Phase Compensation Strategy

ABSTRACT A novel high‐efficiency low‐profile four‐folded transmitarray antenna (FTA) is proposed. The FTA is composed of a dual‐functional transmit‐reflected array (TRA) and a polarized conversion surface (PCS) based on single‐layer PCB. The work proposed a novel dual‐functional transmit‐reflected element and dual‐phase compensation strategy. Firstly, dual‐functional transmit‐reflected element is composed of double pairs of U‐shaped and cross‐shaped patches to realize efficient transmission and reflection, with the losses under 2 dB. Thus, high‐efficiency dual‐functional transmit‐reflected array can be achieved. Secondly, dual‐phase compensation strategy for primary and secondary arrays is put forward to realize low profile folding configuration, which is capable of achieving a profile compression ratio of no more than 0.25. Different from conventional FTA designs, no polarized grids, metal vias or bonding layers are required. For demonstration, one FTA prototype working in W‐band is designed, fabricated and measured. The total size of the FTA is about 60 × 60 × 15.75 mm 3 . The measured peak gain and aperture efficiencies are 28.68 dBi and 21.38% at 89 GHz with 3‐dB gain bandwidth of 10%, which achieved the highest gain and aperture efficiency in current W‐band research. Benefiting from high‐efficiency, low‐profile, single‐layer fabrication, as well as easy integration, the proposed FTA is expected to be a competitive candidate for vehicle radar and LEO satellites communication systems in high frequency of millimeter wave band to terahertz band.