Analysis of different defect configurations in CEBG structures for directive patterns

Electromagnetic bang gap (EBG) materials are periodic structures characterized by forbidden propagation of electromagnetic waves in their band-gap and by the ability to open localized modes inside the band-gap by introducing defects. Cylindrical electromagnetic band gap (CEBG) structures are radially and circularly periodic, and they present pass-band and stop-band to cylindrical electromagnetic waves. By applying a horn-shaped defect in these structures, it has been shown that a re-configurable directive pattern can be obtained. In (P. Ratasjack et al., 2004), experimental results for a reconfigurable CEBG-based antenna have been presented, whereas in (H. Boutayeb et al., 2006), an analysis of the transmission coefficient of CEBG structures and experimental results for a CEBG directive antenna have been proposed. In (H. Boutayeb et al., 2006), a new defect configuration has been proposed for reducing the power supply, but this solution leads to a narrower band. In this paper, new defect configurations are analyzed in order to reduce the number of active elements and the required power supply in CEBG-based agile antennas. The solution with the widest bandwidth is indicated.