Optimization of Resonant Frequency of Circular Patch Microstrip Antenna Using Particle Swarm Optimization Saurabh Kumar * , Rajesh Kumar # Department of Electronics and Communication Engineering Raj kumar Goel Institute of Technology, Ghaziabad (UP), India * saurabh_verma393@yahoo.com # ergangwar@gmail.com B. K. Kanaujia Department of Electronics and Communication Engineering Ambedkar Institute of technology, Delhi, India bkkanaujia@yahoo.co.in Abstract— In this paper, a robust stochastic algorithm called Particle Swarm Optimization (PSO) is used to optimize resonant frequency of circular microstrip patch antenna. A modified formula for resonant frequency is presented using PSO. The obtained results using particle swarm optimization has been compared with experimental and theoretical values of previous papers. The results were in good agreement with experimental value with an average error of 0.18%. Keywords— Particle swarm optimization; Microstrip antenna; Resonant frequency. I. INTRODUCTION The Microstrip antenna is constructed from dielectric substrate and patch metal and that a portion of the metallization layer is responsible for radiation and generally used in microwave and millimeter wave frequencies. Due to their lightweight and simple geometries, microstrip antennas are one of the most popular types of antennas. In high-performance aircraft, spacecraft, satellite, and missile applications, where size, weight, cost, performance, ease of installation, and aerodynamic profile are constraints, and low-profile antennas may be required. To meet these requirements, microstrip antennas can be used [1], [2]. In the design of microstrip antenna, accurate determination of resonant frequency is very important, because the microstrip antenna has narrow bandwidth and can only operate in the vicinity of the resonant frequency [3]. There are number of methods to determine the resonant frequency of circular microstrip antenna. In This paper particle swarm optimization is used to optimize the resonant frequency of circular patch microstrip antenna having various patch diameters, relative dielectric constant. PSO is a robust stochastic optimization technique based on the movement and intelligence of swarms. PSO applies the concept of social interaction to problem solving [4]. II. RESONANT FREQUENCY OF CIRCULAR MICROSTRIP ANTENNA The resonant frequency of a circular microstrip patch antenna for TM nm mode is given by [1] 2 nm nm r X C f a π ε = (1) Where X nm is the mth zero of derivative of Bessel function of order n, c is the velocity of light in free space,  r is relative dielectric constant of the substrate, and a is the physical radius of circular patch, as shown in Fig. 1. The dominant mode is TM 110 (m = n = 1), for which X 11 =1.8412. The TM 110 mode of circular microstrip patch antenna is widely used in microstrip antennas. Fig. 1 Coax-fed circular microstrip antenna 2011 International Conference on Computational Intelligence and Communication Systems 978-0-7695-4587-5/11 $26.00 © 2011 IEEE DOI 10.1109/CICN.2011.124 585 2011 International Conference on Computational Intelligence and Communication Systems 978-0-7695-4587-5/11 $26.00 © 2011 IEEE DOI 10.1109/CICN.2011.124 579 2011 International Conference on Computational Intelligence and Communication Systems 978-0-7695-4587-5/11 $26.00 © 2011 IEEE DOI 10.1109/CICN.2011.124 578