Novel spiral antennas design using swarm intelligence for passive UHF RFID tags

In this paper, new planar spiral antennas for passive RFID tag application at UHF band are designed and optimized using the Artificial Bee Colony (ABC) algorithm. The optimization goals are antenna size minimization, gain maximization and conjugate matching. The antenna dimensions were optimized and evaluated using ABC in conjunction with commercial EM software. Furthermore, a theoretical analysis of the spiral antennas was performed. The input impedance of the printed spiral, was calculated approximately via the Transmission Line Model and the electromotive force induced along the spirals. The theoretical results seem to be in good agreement with the EM solver results. The optimization results produced show that ABC is a powerful optimization algorithm that can be efficiently applied to tag antenna design problems. RFID tags with dimensions less than 4cm, gain that reaches the value of 2 dBi and read distance about 11.7m were among those obtained by the algorithm.