  Alternative designs to an electric-LC (ELC) resonator, which is a type of
metamaterial inclusion, are presented in this article. Fitting the resonator
with an interdigital capacitor (IDC) helps to increase the total capacitance of
the structure. In effect, its resonance frequency is shifted downwards. This
implies a decreased overall resonator size with respect to its operating
wavelength. As a result, the metamaterial, composed of an array of IDC-loaded
ELC resonators with their collective electromagnetic response, possesses
improved homogeneity and hence is less influenced by diffraction effects of
individual cells. The impact of incorporating an IDC into ELC resonators in
terms of the electrical size at resonance and other relevant properties are
investigated through both simulation and experiment.
