Experimental Polarizability Extraction of a Waveguide-fed Tunable Metamaterial Element using SIW Characterization Circuits

We present a method for the experimental extraction of effective polarizabilities of a metamaterial radiator using characterization circuits and a thru-reflect-line (TRL) algorithm. The metamaterial element considered in this work is an electrically small aperture formed with a varactor-tuned, complementary-LC element inserted into the top wall of a substrate-integrated waveguide (SIW). We confirm experimentally the dipolar description of the element by extracting the Lorentzian-constrained effective polarizability using the proposed characterization circuits.