High aperture efficiency millimeter-wave Fabry-Perot cavity MIMO antenna using unprinted and printed dielectric superstrates for n257 band 5G applications

Abstract

This paper presents a Fabry-Perot cavity-backed multiple input multiple output (MIMO) antenna for millimeter-wave (n257 band) 5G applications. The proposed design comprises three orthogonally placed rectangular patch antenna elements printed on a single substrate, complemented by three different variants of partial reflecting surfaces (PRSs) used as superstrates. The inclusion of the PRS significantly enhances the antenna gain at the operating frequency 28 GHz, starting from 7.21 dBi (without PRS) to 12.24 dBi (with unprinted PRS), and further to 12.74 dBi (with double-sided printed PRS). The orthogonal placement of antenna elements enables high inter-port isolation without requiring additional decoupling structures, and results in a compact form factor (1.4λ 0 × 2.7λ 0, where λ 0 is the free-space wavelength at 28 GHz). Furthermore, the design achieves high aperture efficiencies of 87.9 % and 91.5 % for the unprinted and printed superstrate configurations, respectively. Both variants of the MIMO antenna are fabricated and experimentally validated, with results confirming that all key performance parameters fall within desirable limits, thereby making the proposed antenna a strong candidate for advanced 5G applications. © 2025 Walter de Gruyter GmbH, Berlin/Boston 2025.