360° Beam‐Steering Substrate‐Integrated Waveguide Horn Antenna Loaded Monopole Array for Millimetre‐Wave Communications

A millimetre‐wave tilting beam‐steering substrate‐integrated waveguide (SIW) horn antenna is proposed for millimetre‐wave communications. First, a six‐port reconfigurable SIW feeding network using PIN diodes is designed for beam‐steering and each output terminal is directly connected to a horn antenna. Second, to address problems of impedance matching and narrow bandwidth, the horn antenna aperture is loaded with extra substrates and a dipole array. Furthermore, a loaded U‐shaped wall improves the antenna gain and front‐to‐back ratio (FTBR) by suppressing backward radiation. Finally, to enhance the compactness of the previous SIW antenna and generate tilting beams, a tilting beam‐steering SIW horn antenna is proposed and fabricated to tilt the beam in the direction. This antenna incorporates a monopole array and a metal reflector ground. The measured results indicate an impedance bandwidth with dB from 25.60 to 27.72 GHz, a peak gain of 10.5 dBi, and an FTBR exceeding 15 dB. The proposed antenna, which covers a beam‐steering range of in the azimuth plane and up to in the elevation plane, offers a simple and compact structure, high FTBR and full directional coverage without blind spots.