Compact EBG Antennas

This paper presents two designs of compact planar antennas over electromagnetic band gap materials (EBGs). The applications addressed here are for the automotive market and body worn antennas. Researchers demonstrated in E. R. Brown et al. (1993) and R. Coccoili et al. (1999) how antennas combined with EBG structures gain performance enhancements by suppressing surface waves and improving efficiency. Radiating elements can also be mounted above planar EBGs to form high impedance ground planes (HIPs) (Sievenpiper et al., 1999). In this configuration the parallel resonance of the band gap presents an open circuit with a reflection coefficient in phase with the incident electromagnetic fields. Researchers have started to address the synthesis of multiple band EBG structures (Kem et al., 2005) using a genetic algorithm approach. There is considerable interest in developing EBGs for mobile and wireless applications to allow the development of compact antennas over HIPs, to reduce radiation levels into the body from mobile networks and to allow antennas to be placed on the bodywork of vehicles. The challenge is to produce compact EBG elements with a wide bandwidth or multiple bands to cover the mobile communication frequency bands.