Fast Simulation-Driven Feature-Based Design　Optimization of Compact Dual-Band Microstrip　Branch-Line Coupler

摘要

Design of miniaturized microwave components is a challenging task. On onernhand, due to considerable electromagnetic (EM) cross-couplings in highly compressed layoutsrnfull-wave EM analysis is necessary for accurate evaluation of the structure performance.rnConversely, high-fidelity EM simulation is computationally expensive so thatrnautomated determination of the structure dimensions may be prohibitive when using conventionalrnnumerical optimization routines. In this article, computationally efficientrnsimulation-driven design of a miniaturized dual-band microstrip branch-line coupler is presented.rnThe optimization methodology relies on suitably extracted features of a highly nonlinearrnresponse of the coupler structure under design. The design objectives are formulatedrnin terms of the feature point locations, and the optimization is carried out iteratively withrnthe linear model of the features utilized as a fast predictor. The entire process is embeddedrnin the trust-region framework as convergence safeguard. Owing to only slightly nonlinearrndependence of the features on the geometry parameters of the circuit at hand, the optimizedrndesign satisfying prescribed performance requirements is obtained at the low computationalrncost of only 24 high-fidelity EM simulations of the structure. Experimental validation of thernfabricated coupler prototype is also provided.