Phase-spacing optimization of linear microstrip antenna arrays using simulation-based surrogate superposition models

A technique for simulation-driven optimization of the phase excitation tapers and spacings for linear arrays of microstrip patch antennas is presented. Our technique exploits two models of the array under optimization: an analytical model which is based on the array factor, as well as an electromagnetic (EM) simulation-based surrogate model of the entire array. The former is used to provide initial designs which meet the design requirements imposed on the radiation response. The latter is used for tuning of the array radiation response while controlling the array reflection response as well as for validation of the final design. Furthermore, the simulation-based surrogate model allows for subsequent evaluation of the array responses in the beam scanning operation at negligible computational costs. The simulation-based surrogate model is constructed with a superposition of simulated radiation and reflection responses of the array under design with only one radiator active at a time. Low computational cost of the surrogate model is ensured by the EM-simulation data computed with coarse meshes. Reliability of the model is achieved by means of suitable correction carried out with respect to the high-fidelity array model. The correction is performed iteratively in the optimization process. Performance, numerical efficiency, and accuracy of the technique is demonstrated with radiation pattern synthesis of linear arrays comprising 32 microstrip patch antennas by phase-spacing optimization. Properties of the optimal designs in the beam scanning operation are then studied using the superposition models and compared to suitably selected reference designs. The proposed technique is versatile as it also can be applied for simulation-based optimization of antenna arrays comprising other types of individually fed elements. (c) 2015 Wiley Periodicals, Inc. Int J RF and Microwave CAE 25:536-547, 2015.