Bandwidth, efficiency and directivity enhancement of printed antenna performance using planar circularly symmetric EBGs

Planar Circularly Symmetric (PCS) Electromagnetic Band-Gap (EBG) substrates have been recently proposed to suppress the surface waves in printed technology [1] [2]. The major advantage of the PCS-EBGs with respect to structures based on vertical pins [3] [4] is the fabrication simplicity since the dielectric slabs do not need to be perforated. With respect to other planar type of EBG [5], an advantage is that the surface waves launched by a central source are reduced equally in all radial directions. The motivation of this contribution is to design and measure a prototype which demonstrates the suppression of surface waves by a PCS-EBG of a single antenna printed on a dielectric substrate. Thanks to the presence of the PCS-EBG around the antenna, we obtain an enhancement of the bandwidth, efficiency and directivity performances. The study will present some design considerations for the PCS-EBG itself, and then will proceed with the manufactured and measured antennas. The results explicitly show the advantages in terms of bandwidth and radiation pattern of the proposed EBG substrate. A bandwidth of 20% is achieved without significant surface wave losses