Performance prediction of electromagnetic band gap structure for microstrip antenna using FDTD-PBC unit cell analysis and Taguchi's multi-objective optimization method

Abstract

Finite Difference Time Domain-Periodic Boundary Condition (FDTD-PBC) unit cell analysis of Electromagnetic Band Gap (EBG) structure has evolved as a versatile method due to its unique feature of solving Maxwell's equations in time and space domains. Providing a wideband characterization in a single simulation has been a prominent requirement in fields like wave interactions with high-speed electronics and Radar Cross Section (RCS) design. These requirements are otherwise difficult to attempt using full-wave simulation methods like Method of Moments (MoM) and Finite Element Method (FEM). In this work, a novel combination of Taguchi's multi-objective analysis method, along with FDTD-PBC unit cell analysis, is proposed for the optimization and prediction of EBG structure performance. Taguchi's method converges at a significantly faster rate compared to conventional optimization methods such as Particle Swarm Optimization (PSO) and Artificial Neural Networks (ANN). This study identifies important design variables and control factors such as the dimension of a square-shaped EBG unit cell like the width of the patch (w), height of the substrate (h), permittivity of the substrate (εr), gap width between the cells (g) and radius of the via (r). The impact of each of these control factors on the performance of the EBG structure is analyzed. The performance of the EBG structure is predicted using Taguchi's method for those experiments which are not included in orthogonal array (OA). The measured and predicted results are found to be closely matching with a 10% prediction error.