Design and experimental verification of a dual-band metamaterial filter

In this paper, we present the design, simulation, and experimental verification of a dual-band free-standing metamaterial filter operating in a frequency range of 1 THz-30 THz. The proposed structure consists of periodically arranged composite air holes, and exhibits two broad and flat transmission bands. To clarify the effects of the structural parameters on both resonant transmission bands, three sets of experiments are performed. The first resonant transmission band shows a shift towards higher frequency when the side width w₁ of the main air hole is increased. In contrast, the second resonant transmission band displays a shift towards lower frequency when the side width w₂ of the sub-holes is increased, while the first resonant transmission band is unchanged. The measured results indicate that these resonant bands can be modulated individually by simply optimizing the relevant structural parameters (w₁ or w₂) for the required band. In addition, these resonant bands merge into a single resonant band with a bandwidth of 7.7 THz when w₁ and w₂ are optimized simultaneously. The structure proposed in this paper adopts different resonant mechanisms for transmission at different frequencies and thus offers a method to achieve a dual-band and low-loss filter.