This paper presents a novel electromagnetic optimization technique based on Taguchi method. Using the concept of the orthogonal array (OA), Taguchi method effectively reduces the number of tests required in an optimization process. Although this method has been successfully applied in many fields such as chemical engineering, mechanical engineering, IC manufacture, power electronics etc., it is not well known to the electromagnetics community, and only limited applications are available. The goal of this study is to introduce Taguchi method to the electromagnetics community and demonstrate its great potential in electromagnetic optimizations. The implementation procedure of the Taguchi method is presented in Fig. 1. The proposed optimization procedure has been applied in designing a linear antenna array with a sector beam pattern and a microstrip band stop filter (BSF). The desired antenna pattern and frequency response of BSF are successfully achieved. Compared to other optimization techniques, such as the genetic algorithm (GA) and particle swarm optimization (PSO), Taguchi method is easy to implement, and can quickly converge to the optimum solution.