Theory of EMI shielding

The rapid development in nanotechnology has flourished the electronic industries in such a way that the electronic systems are being densely packed with electrical components within the instrument. This explosive growth of electronic, telecommunication, and instrumentation gives rise to an unwanted and undesirable byproduct, which is a novel kind of pollution called electromagnetic interference (EMI). EMI is a conducted and/or radiated EM signal. The impact of EMI is not limited to the malfunctioning of electronic gadgets, but it also affects human health; for example, a continuous exposure to EM radiation increases the risk of cancer, asthma, heart diseases, migraine, and even miscarriage. EMI shielding refers to the reflection and/or absorption of EM radiations using a material; the material acting as a shielding material prevents the penetration of radiations of high frequencies such as radio waves. The blocking of EM radiation using a barrier made up of a conducting or magnetic material is called EMI shielding. This chapter gives a brief overview of different theories of EMI; comprehensive theoretical aspects including reflection, absorption, and multiple reflection parts; mechanism of EMI shielding; and techniques for measurement of shielding effectiveness. Further, consideration and requirement of EMI shielding is discussed along with a review of composite materials for EMI shielding.