Wave propagation in two‐dimensional left‐handed non‐linear transmission line metamaterials

Recent research on harmonic generations in one‐dimensional (1D) left‐handed non‐linear transmission line (LH NLTL) metamaterials has shown that the fundamental wave and its higher harmonics can realise quasi‐phase matching, which in turn ensures the high conversion efficiency of the harmonics. In this study, the authors first present the electromagnetic (EM) theory to describe the generation and propagation of both second‐harmonic (SH) and third‐harmonic (TH) waves in a 2D non‐linear transmission line metamaterial. Then, with the aid of the microwave circuit simulations, they fabricate a 2D LH NLTL metamaterial and demonstrate that an EM wave propagation in such medium has three states: left‐handed (LH), right‐handed (RH), and non‐propagation. Furthermore, the response of the medium to applied field intensity shows that it can realise self‐tuning between LH and RH states for the TH waves.