Accelerated design of CMRC-Based compact rat-race couplers by inverse surrogate modeling

Abstract

The paper presents a technique for rapid design optimization of miniaturized rat-race couplers using inverse surrogate modeling. We consider a class of circuits miniaturized by replacing uniform transmission lines with compact microstrip resonant cells (CMRCs). For the sake of computational efficiency, the optimization process is conducted at the CMRC level using an inverse surrogate model established for a few reference electrical lengths of the cells allocated within the operational bandwidth range of interest. Once established, the surrogate allows for rapid estimation of the optimum CMRC dimensions, the cost of which is up to two EM simulations (including correction steps). The proposed methodology is demonstrated using a 1-GHz rat-race coupler designed for several selected bandwidths.