Abstract: A general model for analyzing the electromagnetic band gap (EBG) structure with bi-anisotropic medium is established by using the plane wave expansion method.An EBG structure consisting of triangular la ttice of air cylinders embeded in a uniaxial chiral medium is simulated.The results show that, when the dielectric constants in the cross section remain the same, an EBG structure with a uniaxialized chiral host (permittivity is positive uniaxial, others are isotropic) possesses a wider complete band gap than the one with an isotropic chiral host.This discovery provides an alternative option for the potential electromagnetic application of the EBG structure.

Key words: chiral medium, dispersion curve, bi-anisotropic, plane wave expansion, electromagnetic band gap