Synthesis of New Artificial Magnetic Conductors for Wideband Ultra Compact Antennas

The use of artificial magnetic conductor (AMC) has proved to be very effective to simultaneously enhance the gain and reduce the thickness of planar antennas. Due to the strong resonant nature of such metamaterials, low profile antennas based on periodic AMC exhibit poor performances in term of bandwidth. The purpose of this study is to use a non intuitive and automatic CAD tool to synthesize an ultra compact planar antenna operating in a wide frequency band. The proposed structure is a Fabry Perrot based cavity antenna made of a partially reflected surface (PRS) above a perfect electric conductor (PEC) including a patch antenna source. The PRS consists in a AMC formed by a dielectric slab with periodically located conducting elements printed on each faces. The aim is to optimize the shape of the basic cell of the periodic PRS-AMC in order to reduce by a factor 5 the thickness of the cavity (lambda/10) while allowing a wide frequency band operation (40%). The process of optimization is carried out using a micro genetic algorithm coupled to a "home made" 3D-TLM electromagnetic software implemented on a parallel IBM-SP3 computer[2].