BANDWIDTH ENHANCEMENT OF MICROSTRIP PATCH ANTENNA USING JERUSALEM CROSS-SHAPED FREQUENCY SELECTIVE SURFACES BY INVASIVE WEED OPTIMIZATION APPROACH

In this paper, we present a novel approach for improving the bandwidth of a microstrip patch antenna using Jerusalem cross-shaped frequency selective surfaces (JC-FSSs) as an artificial magnetic ground plane. The invasive weed optimization (IWO) algorithm is employed to derive optimal dimensions of the patch antenna and JC-FSS element in order for the whole structure to work at 5.8 GHz with consideration of gain. For the most efficient design, the antenna and FSS ground plane are optimized together, rather than as separate components. Simulation results demonstrate that this optimum configuration (the microstrip patch antenna over the artificial magnetic ground plane) have a broad bandwidth of about 10.44%. This wide bandwidth is obtained while the thickness of the whole structure is limited to 0.1λ. Further more desirable radiation characteristics have been successfully realized for this structure. The radiation efficiency of the AMC antenna configuration was found to be greater than 85% over the entire bandwidth. In general by introducing this novel Jerusalem cross artificial magnetic conductor (JC-AMC) in lieu of the conventional perfect electric conductor (PEC) ground plane, the bandwidth enhancement of about 67% and a thinner and lighter weight design has been obtained. Sample antenna and EBG layer are also fabricated and tested, to verify the designs. It is shown that the simulation data in general agree with the measurement results for the patch antennas implemented with FSS ground plane.