Thin frequency selective surface (FSS) superstrate with different periodicities for dual-band directivity enhancement

In this paper we present a novel design of a high directivity resonator antenna that utilizes a two-layered frequency selective surface (FSS) superstrate with different periodicities - as an alternative to a conventional FSS superstrate - for dual band directivity enhancement to reduce its height. Two strip dipole arrays with different periodicities are placed above and below a dielectric layer. The proposed thin FSS superstrate yields 13.1 and 19.54 dBi directivity enhancements at 8.75 GHz and 12.7 GHz, respectively, as compared to that of a patch antenna (6 dBi), while its height is only one half of that of a conventional patch antenna.