Experimental Study of Transmission and Reflection Characteristics of a Gradient Array of Metamaterial Split-Ring Resonators

A study of a non-uniform metamaterial array consisting of six split-ring resonators of varying diameters is conducted experimentally to measure the transmission and reflection characteristics that arise from asymmetry in the longitudinal direction. Such characteristics are examined and compared with their counterpart symmetric scattering coefficients associated with a uniform split-ring array. In the non-uniform array the ring diameters vary in steps of 0.5 mm, which yields a gradient geometry. Inserting the non-uniform array in an X-band waveguide operating below cutoff provides a transmission band wider than that obtained from the uniform array. Different from the uniform array, for which the magnetic resonance frequency is on the left and away from the electric resonance frequency, in the gradient array the magnetic response lies inside the electric band. Index Terms Metamaterials, Split-ring resonators, Gradient array, Electric and magnetic responses.