Design of a cavity-backed slot array unit cell on inverted microstrip gap waveguide

Inverted microstrip gap waveguide is advantageous for millimeter wave application because of its low-loss, self-packaging characteristics and cost-effectiveness. In this work a planar gap waveguide slot array is presented. It is fed by a corporate distribution network realized in inverted microstrip gap waveguide. The structure consists of three layers. The top layer contains subarrays of 2 × 2 radiating slots. This is backed by an air-filled groove gap waveguide cavity. This cavity layer is fed by the inverted microstrip gap waveguide distribution network formed in the air-gap between the middle and bottom layer. The paper presents a design of the 2 × 2 subarray, i.e. the unit cell using simulations in an infinite array environment. The simulation results show that the S11 is below ™11 dB over 57-66 GHz frequency band covering 14% bandwidth, and the simulated directivity is about 39 dBi when evaluated for a 32 × 32 element slot array antenna.