Durbadal Mandal 1 , Rajesh Bera 1 , Sakti Prasad Ghoshal 2 , Rajib Kar 1 1 Department of Electronics and Communication Engineering 2 Department of Electrical Engineering National Institute of Technology Durgapur, West Bengal, India durbadal.bittu@gmail.com Abstract. This paper presents an optimal thinning of large multiple concentric circular ring arrays of uniformly excited isotropic and non-isotropic antennas based on an evolutionary technique Novel Particle Swarm Optimization (NPSO). Circular Antenna Array (CAA) has gained immense popularity in the field of communications nowadays. It has proved to be a better alternative over other types of antenna array configurations due to its all-azimuth scan capability, and the beam pattern which can be kept invariant. In this paper, a nine-ringed Concentric Circular Antenna Array (CCAA) with central element feeding is considered. Extensive simulation results justify the optimization efficacy of the proposed approach for antenna array synthesis. The simulation results show that the number of antenna array elements can be brought down from 279 to 116 for isotropic elements and 101 for non-isotropic elements with simultaneous reduction in Side Lobe Level (SLL) with an approximately fixed first null beam width. Particle Swarm Optimization (PSO), as well is also adopted to compare the results of above Novel Particle Swarm Optimization (NPSO). Keywords— Concentric Circular Antenna Arrays; Particle Swarm Optimization; Novel Particle Swarm Optimization; Thinning; Side lobe Level; Half Power Beam width. 1 Introduction Concentric Circular Antenna Array (CCAA) has several distinct features that make it indispensable in mobile and communication applications. CCAA [1-11] has received considerable interest for its symmetry and compactness in structure. Since a CCAA does not have edge elements, directional pattern synthesized with a concentric circular array can be electronically rotated in the plane of the array without a significant change in the beam shape. CCAA provides higher flexibility in array pattern synthesis and design both in narrow band and broadband applications. Optimal Thinning of a Large Concentric Circular Antenna Array Using Novel Particle Swarm Optimization