A compact microstrip crossover using NRI‐TL metamaterial lines

Abstract

AbstractA practical implementation of a miniaturized crossover is presented using negative‐refractive‐index transmission‐line (NRI‐TL) metamaterial lines. NRI‐TL metamaterial theory has demonstrated that by loading a conventional transmission line with lumped LC elements, a large phase shift per‐unit‐length can be achieved. Employing this technique, the conventional microstrip transmission lines in a three‐section branch‐line coupler crossover are replaced with 90° NRI‐TL lines, and thus a compact NRI‐TL crossover with an area 47 times smaller than the area of its conventional counterpart is demonstrated. Measured results demonstrate that the proposed NRI‐TL metamaterial crossover exhibits a −10 dB |S11| bandwidth of 33% and a |3 dB| |S31| bandwidth of 26% around 1 GHz.