Parasitically loaded hexagonal-SRR mutually coupled wideband antenna for 5 G sub-6 GHz NR mid-bands

A mutually coupled U-stub-based parasitic loading with a hexagonal-split ring resonator (SRR) wideband antenna is investigated for 5 G NR sub-6 GHz applications. A novel patch is designed through a hybrid combination of tri-rectangular patches, designed at the mid-frequencies of n78:3.5 GHz, n77:3.7 GHz, and n79:4.5 GHz. The U-stub is derived by the subtraction of 3.5 GHz and 3.7 GHz rectangular patches. The mutual coupling of surface current density and fields between the U-stub and main patch (4.5 GHz) is achieved by adjusting the coupling-arm dimensions. Furthermore, the mutual coupling amount is enhanced by removing the low-current area from the 4.5 GHz patch by a hexagonal slot cut and introducing a parasitic circular cut-out. This modification reroutes the existing current magnitude from 135.22 to 361.82 A/m. A Mu-Negative (MNG) metamaterial hexagonal-SRR is designed to fine-tune the antenna near 3.5 GHz and also enhances gain and bandwidth for the specified 5 G applications. The hexagonal slot and inner circular cut-out together widen the dual-band bandwidth to a single band (3.26-5.40 GHz). Additionally, SRR loading of the slotted antenna enhances the gain from 4.75 to 5.25 dBi. The simulated and measured results are consistent with a 160 MHz shift in resonance frequency and bandwidth. Therefore, the proposed antenna is well-suited for Wi-MAX, n77, n78, and n79 applications.