Fast simulation-driven design of microwave structures using improved variable-fidelity optimization technique

An improved variable-fidelity optimization algorithm for the simulation-driven design of microwave structures is presented. It exploits a set of electromagnetic-based models of increasing discretization density. These models are sequentially optimized with the optimum of the coarser model being the initial design for the finer one. The found optimum is further refined using a response surface approximation model constructed from the coarse-discretization simulation data. In this work, the computational efficiency of the variable-fidelity algorithm is enhanced by employing a novel algorithm for optimizing the coarse-discretization models. This allows reduction of the overall design time by up to 50% compared to the previous version. The presented technique is particularly suitable for problems where simulation-driven design is the only option, for example, ultra wideband and dielectric resonator antennas. Operation of the presented approach is demonstrated using two examples of antennas and a microstrip filter. In all cases, the optimal design is obtained at a low computational cost corresponding to a few high-fidelity simulations of the structure.