Design of Dual-Band Double Negative Metamaterials

A dual-band artificial magnetic material and then a dual-band double-negative metamaterial structure based on symmetric spiral resonators are presented. An approximate analytical model is used for the initial design of the proposed structures. The electromagnetic parameters of the proposed metamaterial structure retrieved using an advanced parameter retrieval method based on the causality principle show its dual-band nature at microwave frequencies. The proposed double negative metamaterial structure with unit cells with transverse dimensions of 2.5 mm × 2.5 mm has two negative refractive index regions around 6 GHz and 8 GHz. The designed structure can be scaled to other frequencies and is also suitable for planar fabrication