IWO-based Synthesis of Log-Periodic Dipole Array

The Invasive Weed Optimization (IWO) is an
effective evolutionary and recently developed method. Due to its
better performance in comparison to other well-known
optimization methods, IWO has been chosen to solve many
complex non-linear problems in telecommunications and
electromagnetics. In the present study, the IWO is applied to
optimize the geometry of a realistic log-periodic dipole array
(LPDA) that operates in the frequency range 800-3300 MHz and
therefore is suitable for signal reception from several RF services.
The optimization is applied under specific requirements,
concerning the standing wave ratio, the forward gain, the gain
flatness and the side lobe level, over a wide frequency range. The
optimization variables are the lengths and the radii of the dipoles,
the distances between them, and the characteristic impedance of
the transmission line that connects the dipoles. The optimized
LPDA seems to be superior compared to the antenna derived
from the practical design procedure.