Innovative UWB Phase Shifters Using Groove Gap-Waveguide Technology Inspired by Metasurfaces for Beamforming Networks Operating at 100 GHz

This paper presents the design of four phase shifters (+45°, +90°, +135°, +180°) for matrix-based beamforming networks (MB-BFN) in mm-wave antenna arrays. Utilizing groove gap-waveguide (GGW) technology with unequal-width, equal-length transmission lines, the design incorporates metasurface principles to achieve perfect magnetic conductor (PMC) boundary conditions. The metasurface features a “bed-of-nails” structure, where metal pins are connected to a bottom layer and spaced <λ/4 from a top plate. This configuration provides a UWB stop-band over the 80–110 GHz spectrum, ensuring effective phase shifting at 100 GHz within the ultra-wideband range.