Using particle-swarm optimization for antenna design

From a historical perspective, electromagnetic modelling and its techniques of optimization are relatively new to the academic community. Their existence has facilitated the development of complex electromagnetic structures, and provides invaluable aid when designing electronic products that face strict radiation legislation. This thesis provides an introduction to electromagnetic modelling using the Partial element equivalent circuit (PEEC) method, and an in-depth description and evaluation of the technique of particle-swarm optimization. PEEC is a current research topic at the Embedded Internet Systems Laboratory (EISLAB). This approach describes electromagnetic models and couplings by equivalent circuits. It arises from inductance calculations and allows for inclusion of lumped elements describing voltage sources, resistances, inductances, and capacitors. As a direct result of the research, a local electromagnetic solver is available. The main objective is to merge the existing EISLAB solver with the particle- swarm algorithm, for optimizing various electromagnetic structures. A technique for calculating the radiated field from the models is also discussed and used for the purpose of optimizing a dipole array. Particle-swarm optimization was developed in 1995 and models the movement and intelligence of swarms. Behind the algorithm are a social psychologist and an electrical engineer, who developed the optimizer inspired by nature. The technique has proven successful for many electromagnetic problems and is a robust and stochastic search method. The optimization algorithm alters the input file to the PEEC solver, thus affecting the physical description of the electromagnetic structures, and evaluates the result that is returned from the solver. The particle-swarm algorithm worked well on several problems. It was used for optimizing mathematical functions and electromagnetic problems. The optimized antennas were determined to have desired resonant frequencies, high gain, and low weight and return losses. The patch antennas turned out to be troublesome to handle, thus some improvements such as inclusion of ground planes, are discussed.Validerat; 20101217 (root