Millimeter-Wave Quasi-Optical Feeds for Linear Array Antennas in Gap Waveguide Technology

A realization of the quasi-optical (QO) feed concept for linear millimeter-wave (sub-)array antennas is demonstrated in gap waveguide technology. The proposed feed architecture employs an input transition from a ridge gap waveguide (RGW) to a groove gap waveguide (GGW), a radial (H-plane sectoral) GGW section, and a transition to an output RGW array. A design decomposition approach is presented to reduce simulation complexity. Several 20-element QO feed implementations are investigated at W-band demonstrating a 20% relative bandwidth (85–105 GHz), 0.5 dB insertion loss, and a capability of an amplitude taper control within the 10–20 dB range.