Structural Evolution Design and Optimization for the Metamaterials with Broadband Frequency-Independent Negative Permeability

Broadband frequency-independent operations are strongly desired in metamaterial applications. In this work, we unveil the roles of each element acting in the metamaterial unit with a structural evolution design methodology. Starting with split ring resonator (SRR) prototype structures, we focus on the variations of elements on the magnetic response and successfully realize the structures of clock-like and wire pairs with double and broadband frequency-independent negative permeability (0.725 to 0.9THz, =-0.75). Our results suggested that multi-resonance modes induced by elements integration could extend working bands. By well parameters tuning, the phase mismatch during multi-modes interactions could be utilized to modify the working bands with frequency-independent features as well. Our investigations are beneficial to the design of functional negative permeability metamaterials with broadband operations.