We report the theoretical work on the photonic band gap structures suitable for microwave frequency region formed by magnetic materials (ε = 9.87 and μ = 2.17) using plane wave expansion method. The structures under analysis are two-dimensional square and triangular lattices. The calculated band gap between 10 and 20 GHz region is anlaysed for the effect due to lattice spacing and the property of the material. The results are also compared with that of pure dielectric case. Obtained results indicate that both impedance and effective refractive index are responsible for the gap width and mid-gap frequency. © 2006 Elsevier B.V. All rights reserved.