Directivity Enhancement of Double-Slot Antennas by a Woodpile Electromagnetic Bandgap

Resonator antennas made from simple radiating devices placed between a woodpile and a ground plane are studied. A woodpile is a dielectric three-dimensional electromagnetic bandgap material that presents large stop-bands. A woodpile super- strate and a metallic plane, placed at an appropriate distance from each other, are equivalent to a woodpile cavity, the transmission response of which presents peaks inside the bandgaps. This property can be exploited to obtain highly directive radiators from low-directivity antennas. The cavity is fed by a double-slot antenna. The role of the permittivity of the constituent material of the rods is investigated. An evaluation of the bandwidth is performed for the directivity enhancement of the studied antennas, and the role of the woodpile covering area is pointed out.