Low cross polarized leaf shaped broadband antenna with metasurface as superstrate for sub 6 GHz 5 G Applications

Abstract

This article presents the design, circuit model analysis, and realization of a metasurface-based novel leaf-shaped antenna for sub 6 GHz 5 G NR frequency bands like n77 (3.3–4.2 GHz), n78 (3.3–3.8 GHz), n79 (4.4–5 GHz), and n90 (2.4–2.6 GHz) applications. Primarily, a leaf-shaped microstrip planar antenna is designed and provides a broad impedance bandwidth of 77.43% (2.2–4.98 GHz), a peak gain of 4.51 dBi, and a high radiation efficiency of 94.16%. The planar antenna is integrated with a 5 × 3 elements periodic metasurface (MS) array to enhance radiation performance. Both the radiating leaf planar and the MS layer have been designed on a low-cost FR4 epoxy substrate, and equivalent circuit models have been developed for both successively to validate the EM simulated results. The overall dimensions of the planar antenna with MS layer are 0.45 λ0 × 0.27 λ0 × 0.108 λ0, (λ0 corresponds to lowest resonant frequency f=2.7 GHz). The tested antenna with MS superstrate covers a broad range of operating frequencies from 2.29 to 4.78 GHz (2.49 GHz) with a − 10 dB impedance fractional bandwidth of 70.43% and has an excellent reflection coefficient of more than − 35 dB for the entire operating band. The experimental peak gain and higher radiation efficiency are 8.76 dBi and 96.6%, respectively. Moreover, all these parameters are extremely high in single-layer planar antennas, including the stable omnidirectional radiation pattern with very low cross-polarization of − 53.34 dB.