Using particle-swarm optimization for antenna design

Abstract: 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.