Directional Dual-Band Slot Antenna with Dual-Bandgap High-Impedance-Surface Reflector

A compact dual-band high-impedance-surface EBG struc- ture is employed as a re∞ector for a dual-band annular-slot antenna. The re∞ector comprises an array of miniaturized EBG cells which uti- lizes square patches augmented by four S-shaped corrugated arms to reduce the resonant frequency of the proposed EBG structure. In or- der to broaden the bandwidth and adjust the frequency ratio for the dual-band EBG structure, a log-periodic spacing between the S-shaped strips is introduced. The combination of microstrip-fed annular slot and EBG re∞ector provides directional properties for both frequency bands with reduced size and low-proflle.