Circular Antenna Array Synthesis Using Firefly Algorithm Ashraf Sharaqa, Nihad Dib Department of Electrical Engineering, Jordan University of Science and Technology, P. O. Box 3030, Irbid 22110, Jordan Received 25 September 2012; accepted 10 January 2013 ABSTRACT: In this article, the design of circular antenna arrays (CAAs) and concentric circular antenna arrays (CCAAs) of isotropic radiators with optimum side lobe level (SLL) reduction is studied. The newly proposed global evolutionary optimization method; namely, the firefly algorithm (FA) is used to determine an optimum set of weights and positions for CAAs, and an optimum set of weights for CCAAs, that provides a radiation pattern with optimum SLL reduction with the constraint of a fixed major lobe beamwidth. The FA represents a new algorithm for optimization problems in electromagnetics. It is shown that the FA results provide a SLL reduction that is better than that obtained using well-known algorithms, like the particle swarm optimization, genetic algorithm (GA), and evolutionary programming. V C 2013 Wiley Periodicals, Inc. Int J RF and Microwave CAE 24:139–146, 2014. Keywords: antenna arrays; circular arrays; optimization techniques; firefly algorithm I. INTRODUCTION Antenna arrays are widely used in modern communication and radar systems [1, 2]. In contrast to linear antenna arrays [3–6], the radiation patterns of circular antenna arrays (CAAs) and concentric circular antenna arrays (CCAAs) inherently cover the entire space and the main lobe could be oriented in any desired direction. To pro- vide a very directive pattern, it is necessary that the fields from the array elements add constructively in some desired directions and add destructively in other direc- tions. Thus, recently, the design of antenna arrays with minimum side lobes level has been a subject of very much interest in the literature. To accomplish this, differ- ent global evolutionary optimization techniques [e.g., particle swarm optimization (PSO), genetic algorithm (GA) and evolutionary programming (EP)] have been used in the synthesis of nonuniform CAAs and CCAAs [7–22]. In this article, the newly proposed global optimi- zation method, firefly algorithm (FA) [23] is used to design nonuniform CAAs and CCAAs of isotropic radia- tors with optimum side lobe level (SLL) reduction. FA is based on the attractiveness and movements of fireflies [23, 24]. Recently, the FA has been successfully applied in the electromagnetics area, where it has been applied to the synthesis of antenna arrays [25–27]. In this article, for CAAs, FA is used to determine an optimum set of weights and positions that provide a radiation pattern with opti- mum SLL reduction with the constraint of a fixed major lobe beamwidth. On the other hand, for CCAAs, it is used to determine an optimum set of weights only that accom- plishes the same objective of getting an optimum SLL reduction. The rest of this artcile is organized as follows: In Section II, FA is briefly described. In Section III, the geometry and array factor for both the CAA and CCAA are presented. Moreover, the fitness function is given. Then, based on these models, in Section IV, numerical results are given and compared to the results obtained using other optimization methods. Finally, the article is concluded in Section V. II. FA FA is a new nature inspired algorithm developed by Yang [23, 24]. Several well-known optimization techniques; such as invasive weed optimization (IWO) [28], ant col- ony optimization (ACO) [29], PSO [30] and recently FA mimic insect behavior in problem modeling and solution. FA is based on the flashing light of fireflies which is pro- duced by a process of bioluminescence. The objectives of flashing system in fireflies are to attract marrying partners, to attract potential victim, and to give a warning sign. The attractive process between fireflies is based on their light Correspondence to: N. Dib; e-mail: nihad@just.edu.jo V C 2013 Wiley Periodicals, Inc. DOI 10.1002/mmce.20721 Published online 8 April 2013 in Wiley Online Library (wileyonlinelibrary.com). 139