Design of Compact Multi-band EBG Structures

Several novel compact multiple-band high-impedance surface EBG structures are presented. By utilizing four S-shape corrugated arms or spiral arms connected to the edge of a small square patch to increase the inductance, the resonant frequency of the EBG structure can be significantly reduced. In order to broaden the width of the stopband and adjust the ratio of the centre frequencies for multi-band EBG a log periodic distance between the S-shape strips is implemented. The effects of the parameters of the EBG structure on the width of stopbands are discussed in detail. The results show that the proposed novel EBG structure can provide more multiple bandgap and reduce the EBG size for a fixed periodicity. This proposed EBG can be usefully applied to multiple frequency antennas and low frequency antennas.