Impedance Bandwidth Enhancement of a Novel Fabricated Fractal Patch Antenna Using Invasive Weed Optimization Algorithm

Abstract

In this paper, the possibility of different configurations of a novel Koch fractal geometry for the miniaturization and broad banding of a microstrip patch antenna, while maintaining its gain and radiation pattern, is investigated. To achieve the best results, the invasive weed optimization (IWO) algorithm, which is shown to be very robust and adaptive, is used for optimization. The whole design procedure is auto-controlled by linking, the high-frequency structure simulator with MATLAB software. For the first configuration, IWO is used to find the best location of feed point to minimize the return loss, e.g., S ₁₁ ($\left| {S_{11} } \right| < {-}10\;{\text{dB}}$) and hence increasing the radiation efficiency of the proposed antenna. $\left| {S_{11} } \right|$ of about −40 dB was achieved. Next, the proposed fractal with air-filled substrate and a ring slit is presented. The key design parameters such as air gap height, the slot gap width, location of feed point have been optimized using IWO to obtain the best possible bandwidth. Simulation results show a fractional impedance bandwidth of about 40% (2.42–3.59 GHz). This band is used by weather radar and some communication satellites. Gain and radiation pattern of the proposed antenna are acceptable within the frequency bandwidth. A prototype of the antenna is also fabricated and tested. Measured parameters are in good agreement with the simulated results.