Electromagnetic shielding properties of open-pore Fe-Ni foams

The electromagnetic interfering (EMI) shielding properties of open-pore Fe-Ni foams prepared by a patented technique in the frequency range from 0.03 MHz to 1500 MHz was investigated using a coaxial cable method. The results indicate that the open-pore Fe-Ni foams exhibit high shielding effectiveness (SE) between 60 dB and 85 dB in the whole frequency range, but the SE value of the foams is similar to that of aluminum alloy sheets in the frequency range from 0.03 MHz to 400 MHz. Moreover, the SE value of open-pore Fe-Ni foams is determined by the foam structure such as pore size and porosity. The SE value increases significantly with the open-pore size and porosity decreasing. However, the porosity change influences the SE value less than other factors when the pore size and thickness is certain.