Cost-Effective High-Performance Air-Filled SIW Antenna Array for the Global 5G 26 GHz and 28 GHz Bands

A cost-effective, compact, and high-performance antenna element for beamforming applications in all fifth-generation (5G) New Radio bands in the [24.25–29.5]
$ \,$
GHz spectrum is proposed in this letter. The novel antenna topology adopts a square patch, an edge-plated air-filled cavity, and an hourglass-shaped aperture-coupled feed to achieve a very high efficiency over a wide frequency band in a compact footprint (
$\boldsymbol{{0.48} \lambda _0 \times \text{0.48}\lambda _0}$
). Its compliance with standard printed circuit board (PCB) fabrication technology, without complex multilayer PCB stack, ensures low-cost fabrication. The antenna feedplane offers a platform for compact integration of active electronic circuitry. Two different modular 1
$ \boldsymbol{\times }$
4 antenna arrays were realized to demonstrate its suitability for broadband multiantenna systems. Measurements of the fabricated antenna element and the antenna array prototypes revealed a
$-$
10 dB impedance bandwidth of 7.15 GHz (26.8%) and 8.2 GHz (30.83%), respectively. The stand-alone antenna features a stable peak gain of 7.4
$ \,\pm \,$
0.6
$ \,$
dBi in the [24.25–29.5]
$ \,$
GHz band and a measured total efficiency of at least 85%. The 1 × 4 array provides a peak gain of 10.1
$ \,\pm \,$
0.7
$ \,$
dBi and enables grating-lobe-free beamsteering from
${-}\text{50}^\circ$
to
$ \text{50}^\circ$
.