Photonic bandgap crystals on magnetic-dielectric for microwave frequency applications

The variation of magnetic permeability of substrate on Photonic Band Gap (PBG) has been studied for microstrip type periodic metallic structure and the experimental findings will be presented and discussed. Periodic structure was carved out in the metallic foil of 18 micron thickness and was put on the composite of magnetic and dielectric substrate. As the dielectric constant of the substrate affects the band gap for the photons in the microwave region, the combined effect of magneto-dielectric substrate have been studied here for different combination of ferrite materials with different composition and different sintering temperature. The substrate of Ni-Zn ferrite was prepared on the Perspex sheet of desired dimensions. The behavior of variation of band gap was also been studied for the air as dielectric material of the substrate. We found a well defined PBG and the band gap increases and transmission loss decreases in the microwave region with appropriate combination of magnetic and dielectric substrate. Thus it could be concluded that the dielectric constant viz. a viz. magnetic permeability plays an important role in the formation of broad band photonic materials for the microwave applications such as filters, antennas, frequency selective surfaces etc. Further work is going on to fabricate the patch antenna on the PBG embedded ground plane.