Rapid simulation‐driven design of miniaturised dual‐band microwave couplers by means of adaptive response scaling

Abstract

One of the major challenges in the design of compact microwave structures is the necessity of simultaneous handling of several objectives and the fact that expensive electromagnetic (EM) analysis is required for their reliable evaluation. Design of multi-band circuits where performance requirements are to be satisfied for several frequencies at the same time is even more difficult. In this work, a computationally efficient design of dual-band microstrip couplers is demonstrated by means of an adaptive response scaling (ARS) technique. ARS is a surrogate-assisted method that exploits a fast surrogate of the high-fidelity EM-simulation model of the coupler at hand constructed from its corrected equivalent circuit. ARS identifies nonlinear frequency and amplitude response scaling that accommodates the misalignment between the low- and high-fidelity models. Due to exploiting the knowledge embedded in the low-fidelity model ARS surrogate exhibits excellent generalisation capability. It is demonstrated here by optimisation of a dual-band microstrip coupler with enhanced bandwidth, working at 1 GHz and 2 GHz frequencies. The optimised design has been obtained at the cost of just a few high-fidelity EM simulations of the structure. Numerical comparisons indicate superiority of ARS over competitive surrogate-assisted techniques. Experimental validation is also provided.