Abstract
Shielding of electromagnetic radiation is normally contributed by impedance mismatched interface induced reflection and adsorption due to material polarization. Contribution by the third mechanism known arising from multi-scattering within medium however is small and negligible. This thesis intends to develop a novel technology of electromagnetic interference shielding based on thin films with high porosity and shielding is dominated by multi-scattering mechanism. Carbon nanotubes, copper and copper monosulfide are introduced into porous thin films made of lithium chloride and polyacrylonitrile and shielding experiments reveal an increase in shielding effectiveness dominated by multi-reflections.