Soft Computing Techniques for Mutual Coupling Reduction in Metamaterial Antenna Array

Application of soft computing techniques for various metamaterial designs and optimizations is an emerging field in the microwave regime. In this paper, a global optimization technique, namely, particle swarm optimization (PSO), is used for the design and optimization of a square split ring resonator (SSRR) having a resonant frequency of 2.4？GHz. The PSO optimizer yields the structural parameters, which is further simulated and validated with the optimized value. This optimized structure results in the mutual coupling reduction in a microstrip antenna array designed for wireless application. 1. Introduction Soft computing techniques play important role in the design and optimization in various electromagnetic applications including antenna engineering. The aim of these techniques is to tolerate imprecision and uncertainties and yet yield quick solutions that are both robust and economically viable. Recent developments in the rapidly growing field of metamaterials have caught the attention of researchers worldwide due to its intrinsic properties leading to exciting applications in engineering such as the invisibility cloak, high-performance frequency selective surfaces (FSS) and radomes, and so forth. An important aspect of these metamaterial applications is the design and optimization towards actual hardware realization for which soft computing techniques have emerged as a potential tool due to their promise to treat the enormous complexity in analysis with relative ease [1]. Microstrip patch antennas are widely used in wireless communication in various platforms including aerospace due to their features like compactness, compatibility with MMIC (conformal) design, and high performance. In practice, mutual coupling effects which degrade the antenna performance are predominant [2]. Such mutual coupling effects are often mitigated by the use of EBG structures, which however makes the antenna array system very complex [3]. In order to overcome this complexity, a simple square split ring resonator (SSRR) is proposed in this paper. Such an application requires design of metamaterial structures at a desired frequency range (equivalent to the resonant frequency of the antenna array, mutual coupling of which is to be reduced). A particle swarm optimization (PSO) algorithm is developed here, which optimizes the resonant frequency and provides the structural parameters. This optimized design is further used for mutual coupling reduction and performance enhancement of the antennas. In this paper, an array of simple single ring SSRR is used for reduction of mutual