EM (electromagnetic) shielding is the process of limiting the flow of EM fields between two locations by a barrier. Refection, absorption, and attenuation of the shielding materials are applied to reduce the effects of the electromagnetic field of the radiation sources.

As with the characteristics of high strength, rigidity, energy absorption and combined with a high reflection coefficient and good electrical conductivity, metal foams are potential shielding materials against electromagnetic radiation. In addition, carbon foam materials can be used to solve EMI (electromagnetic interference), whereas the mechanical properties of carbon foam are poor, which limit the applications in particular fields.

Metal foam
Metal foam has certain advantages in electromagnetic shielding, and it has been demonstrated to be an attractive option for EM shielding applications without imposing structural issues. When the electromagnetic shielding efficiency is equivalent, the metal foam material is only 1/3 weight of the traditional ventilated waveguide. At present, metal foams would perform their EM shielding mainly by the reflection loss mechanism in the low-frequency range and give priority to the absorption loss mechanism at the upper-frequencies.

Carbon foam
Carbon foam can be used for numerous EMI shielding applications including ships, tactical shelters, fixed site shelters, and other electronic enclosures.

Carbon foam enclosures can be tailored to provide greater than 60 dB of RF shielding from 100MHz to 20 GHz. The advantage of using carbon foam in an electronic enc osure is that it serves as a multifunctional material by providing both EMI shielding and structure as a composite core material for the enclosure.