Synthesis of Split-Rings-Based Artificial Transmission Lines Through a New Two-Step, Fast Converging, and Robust Aggressive Space Mapping (ASM) Algorithm

Abstract

This paper is focused on the synthesis of artificial transmission lines based on complementary split ring resonators (CSRRs). The considered structures are microstrip lines with CSRRs etched in the ground plane and microstrip lines loaded with both CSRRs and series capacitive gaps. An aggressive space mapping (ASM) optimization algorithm, able to automatically generate the layout of these artificial lines, has been developed. The tool has been optimized in order to achieve fast convergence and to provide accurate results. The main relevant aspects of the proposed algorithm (based on a novel two-step ASM optimization approach) are: 1) the capability to provide the implementable circuit elements of the equivalent circuit model of the considered artificial lines and 2) the ability to converge in a few (unprecedented) iteration steps, due to a new procedure to generate the initial layouts (which are very close to the final ones). First, the software is tested through the synthesis of several CSRR-based microstrip lines, and then some practical application examples of such artificial lines are reported to illustrate the potential of the proposed synthesis tool.