Substrate-Integrated Coaxial Line Fed Air-Filled SIW Antenna for the 28 GHz 5G Bands

Abstract

A compact, cost-effective antenna element for beamsteering applications is developed for efficient operation in the fifth-generation (5G) n257 (26.5 GHz, 29.5 GHz) and n261 (27.5 GHz, 28.35 GHz) frequency bands. An air-filled cavity-backed patch antenna topology is proposed. Feeding the antenna with a substrate-integrated coaxial line (SICL) feed yields excellent antenna-to-platform isolation, which is represented by a front-to-back ratio (FTBR) of at least 22 dB, while avoiding distortions in the radiation pattern. Moreover, this feed implementation allows rotation over 360 degrees without any loss in performance. The total efficiency is increased (above 92%) by employing an air-cavity, resulting in an improved realized gain response, ranging from 7.25 dBi to 8.35 dBi, and a half-power beamwidth around 72 degrees. By assembling single-layer standard manufactured printed circuit boards (PCBs), a cost-effective design is obtained.