Design method of EBG material with wide defect band

A new electromagnetic band gap (EBG) material with defect is proposed. It is constructed by double-layer frequency selective surfaces (FSS) periodically arranged in the zdirection. A periodicity defect is introduced in the middle of the structure. Resulted EBG material with defect is composed of two double-layer FSS with wavelength spacing between them. Due to the presence of the defect, an allowed frequency band is created within the material band gap. The width of the formed defect band is increased compared to classical EBG materials with defect. The new material is applied in the design of a resonator antenna. The resonator, formed by a double-layer FSS and a metallic ground, is fed by a patch source placed at the proximity of the ground. The antenna bandwidth is significantly improved by virtue of employing the EBG material with defect of wider allowed band. The participation of each FSS layer in the antenna bandwidth enhancement is described.