D-Band High-Gain Planer Slot Array Antenna Using Gap Waveguide Technology

A D-band high-gain slot array antenna with a corporate-fed distribution network based on gap waveguide structures is proposed at 140 GHz. To overcome the fabrication challenges at such high frequency, the gap waveguide technology is deployed in which good electrical contact between different parts of the waveguide structure is not required. The proposed sub-array has four radiating slots that are excited by a groove gap cavity and the cavity is coupled to an E-plane groove gap waveguide via a rectangular coupling slot. A wideband and low-loss corporate feeding network based on the combined ridge gap waveguide and E-plane groove gap waveguide is designed for this case and the whole array antenna consists of $16\times 16$ radiating slots. A standard WR6 waveguide flange is embedded at the bottom side of the feeding structure to excite the array antenna. To evaluate the design, a prototype is fabricated in Aluminum using standard CNC milling technique. The measurement results show that an impedance bandwidth of 20% (124.1–151.7 GHz), a peak gain of 31.5 dBi, and maximum efficiency of 94% are achieved for the $16\times 16$ -element array antenna. The results show that the proposed array antenna has an excellent performance among the previously published D-band planar array antennas and could be a promising candidate to be used in the development of D-band front-end modules.