Wideband Open-Ended Ridge Gap Waveguide Antenna Elements for 1-D and 2-D Wide-Angle Scanning Phased Arrays at 100 GHz

A new antenna element type based on the open-ended ridge gap waveguide (RGW) is proposed for phased array applications. This element type is of a particular interest at high millimeter-wave frequencies (\geq 100 GHz) owing to a contactless design alleviating active beam-steering electronic integration. The key challenge addressed here is a realization of a wide fractional bandwidth and a wide scan range with high radiation efficiency. We demonstrate a relatively simple wideband impedance matching network comprised of an aperture stepped ridge segment and a single-pin RGW section. Furthermore, the E- and H-plane grooves are added that effectively suppress antenna elements' mutual coupling. Results demonstrate a wide-angle beam steering (\geq \text{50}^\circ) over \geq {20\%} fractional bandwidth at the W-band with \geq {89\%} radiation efficiency that significantly outperforms the existing solutions at these frequencies. An experimental prototype of a 1 × 19 W-band array validates the proposed design concept through the embedded element pattern measurements.