A broadband negative refractive index meta-atom for quad-band and sensor applications

A new modified hexagonal design structure with broadband-negative refractive index metamaterial was proposed in this manuscript. The proposed structure was composed of two symmetrical metallic layers which had same thickness and an FR4 dielectric layer that was sandwiched between these metallic layers. Frequency domain solver of CST microwave studio, which is commercially available was utilized to observe the results of the design structure. The design structure was analyzed by two orientations with respect to the incident plane wave. For normal wave incidence, the suggested structure displays broadband negative refractive index (3.18 GHz) and (0.9 GHz) with a higher effective medium ratio (17.26) that was indicated small electrical size of the structure, whereas for parallel wave incidence, broadband negative refractive index (2.45 GHz), (1.22 GHz), and (1.93 GHz) bandwidth with a higher effective medium ratio (28.01) was obtained. The negative refractive index was verified by simulation and measurement for quad-band applications. Furthermore, the effective medium ratio (lambda/a) of the proposed broadband negative refractive index metamaterial was considerably improved compared to previous suggested multiband metamaterials. In addition, the design structure can also be utilized as a pressure sensor.