Gap Coupled Symmetric Square Split Ring High EMR Resonator-Based Metamaterial for S-, C-, and X-Bands Wireless Applications: Simulation and Experiment

Abstract

This article describes a metamaterial (MTM) based on a symmetric square ring resonator (SSRR) that exhibits epsilon negative (ENG) and near-zero index (NZI) properties. A 0.035 mm thick copper resonator is used to construct the proposed asymmetric MTM structure, designed on a 1.5 mm thick FR-4 substrate for microwave applications. The MTM structure attained optimum resonance at frequencies corresponding to the microwave frequency range of the S, C, and X bands, 2.88 GHz, 4.78 GHz, and 10.9 GHz, respectively. The near-zero index characteristics are realized in the frequency ranges 2.22–3.17 GHz, 4.52–5.10 GHz, and 9.63–11.36 GHz, while the ENG characteristics are realized in the frequency ranges 2.1–3.2 GHz, 4.57–5 GHz, and 9.7–11.4 GHz. The electrical dimensions of the structure are 0.139λ × 0.139λ × 0.014λ, corresponding to an estimated wavelength of 2.88 GHz. The effective medium ratio (EMR), which for this construction is 7.194, indicates the compactness of the design structure. Using CST 2019 simulation software, the proposed structure is designed and developed before its construction and performance evaluation. The circuit was validated by comparing the S21 response using the Advanced Design System (ADS) software. The response of S21 from the proposed MTM structure was almost identical when it was tested through simulation (using CST and ADS software) or actual measurements. The compact size, substantial electromagnetic response (ER), negative permittivity, almost zero permeability, and refractive index of this MTM make it perfect for wireless applications in S-, C-, and X-bands.