Nonlinear Multiconductor Transmission Line Analysis of Broadband Switching Metamaterials

In this paper, we present a nonlinear multiconductor transmission line model to analyze the time-domain and nonlinear responses of broadband switching metamaterials. This analysis employs coupled transmission lines loaded with nonlinear elements to model the response of the metamaterial structures to a vertically polarized free-space excitation. Using this analysis we first examine the time-domain response of a broadband switching metamaterial structure loaded with high-speed Schottky diodes. We then show that this structure's response to incident power can be effectively inverted by replacing these Schottky diodes with varactor diodes. Experimental results are presented for both structures in WR-284 waveguide, which show good agreement with results generated from full-wave and transmission line analysis. We also use the circuit model to simulate power-dependent material parameters and both the input and output third-order intercept point for both the Schottky-loaded and varactor-loaded metamaterials.