Millimeter-Wave Beam-Tilting Cavity Backed Slot Array Antenna Based on Nonuniform Slow Wave Substrate Integrated Waveguide

The 5G communication enabled by the millimeter-wave (mmWave) technology requires flexible beam direction and coverage for diverse applications. The beam-tilting antenna is a low-cost scheme to satisfy the custom beam radiation in the real-life scenario. This communication presents a novel beam-tilting cavity backed slot array antenna based on nonuniform slow wave substrate integrated waveguide (SW-SIW) for mmWave applications. By introducing the nonuniform slow wave (SW) structure into the substrate integrated waveguide (SIW), the phase of the incident wave for the radiating slots is adjusted to generate tilted beam. To validate the concept, two cavity backed slot array antennas are designed with 33° tilted beam. The first cavity-backed array antenna achieves a minimized element spacing of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$0.48\lambda _{0}$ </tex-math></inline-formula> and 33° tilted beam with the help of nonuniform SW structure. Based on this subarray, a four-element cavity-backed array antenna achieves the measured 33° tilted beam with a gain of 10.7 dBi and the suppressed the sidelobe level (SLL) of −11 dB. The proposed compact low-profile low-cost beam-tilted array antenna provides a flexible radiation for 5G mmWave communications.