Experimental Studies on the Effect of Substrate Dielectric Constant on the Resonant Frequency of Split-Ring Resonator Metamaterial Structure

The results of an experimental study for tuning the resonant frequency of a split ring resonator (SRR) metamaterial structure at microwave frequencies, by changing the material and thickness of substrate are presented. The SRR structure is fabricated by photochemical etching on a copper foil glued on a thin low loss polymer film of negligible thickness. The transmission properties are studied using a unit cell of SRR between two monopole antennas. The materials used for the fabrication of substrate are the Poly Methyl Methacrylate (PMMA) and Wax. The experimental results predicts the possibility of tuning the resonant frequency of the SRR unit to any desired value by changing the material or thickness of the substrate and are in good agreement with theoretical expectations. This possibility may be used for the fabrication of wide band frequency selective and cloaking materials. This method may be extended to the design and fabrication of tunable negative index materials.