Experimental Verification of Below-Cutoff Propagation in Miniaturized Circular Waveguides Using Anisotropic ENNZ Metamaterial Liners

摘要

This paper presents experimental verification of below-cutoff transmissionthrough miniaturized waveguides whose interior is coated with a thinanisotropic metamaterial liner possessing epsilon-negative and near-zero (ENNZ)properties. These liners are realized using a simple, printed-circuitimplementation based on inductively loaded wires, and introduce an HE$_{11}$mode well below the natural cutoff frequency. The inclusion of the liner isshown to substantially improve the transmission between two embeddedshielded-loop sources. A homogenization scheme is developed to characterize theliner's anisotropic effective-medium parameters, which is shown to accuratelydescribe a set of frequency-reduced cutoffs. The fabrication of the linedwaveguide is discussed, and the experimental and simulated transmission resultsare shown to be in agreement.