Executive Summary : | Due to use of large number of power electronic and power control devices used in our industries and at home, the amount of EM pollution silently affects not only the power electronic devices but also the humans. Every power devices including high power switching circuits are the sources of EM radiations. These circuits involve time dependent current that produce EM radiations even for frequencies above several GHz. Though these are non-ionizing radiations that do not modify the DNA of our system, the exposure time coupled with power would affect the soft tissues like cornea and also affect children with more probability. For example, a very low power of 2 mW can affect our cornea and damage the eyesight to a greater extent. The conventional way of using reflectors or Faraday cages to avoid EM pollution is not effective since it just migrates the problem from one location to another. Absorption is the best way to completely remove the pollution in the power devices or at potential targets. In this regard, it is planned to model and fabricate a low-density, corrosion free and moldable polymer based multi-layered composite for 99.9999% (60dB) absorption of the EM radiation. Absorption based shielding structures is expected to be low-dense, moldable, easily fabricated and corrosion free. Polymers are the best base matrix in which suitable fillers can be incorporated. Deviating away from the simple mixing, the combinations should be able to increase the electric and magnetic dipoles by forming an integral structure to the polymer. For example, a ferroelectric polymer with embedded magnetic particles has an enhanced electric polarizability and magnetization. The design of absorber would not be complete without an impedance matching layer that reduce the reflection. This is achieved by incorporating multi-layered graded index layer that match well with the absorbing base. At the same time, the reflected radiation from the back-surface of the absorber has to be tackled by enhancing the multiple scattering and absorption in the volume of the absorber by incorporating nano-conducting forms either as nano-wires or nano-flakes. These help to partly scatter, absorb and rest transmitted. This greatly enhances the effective attenuation constant. The modeling of the absorber is therefore an essential part. In this proposal, combination of analytical, full-wave simulation and experimental data to effectively target the best choice of material and size of layers. Targeted for the absorption of about 60dB, the developed structure would reduce the pollution caused by power systems and switching devices and useful for both power device manufacturers and home applications. |