Water , air and Sound pollution is well within the human perception but esoteric pollution of frequency spectrum called Electro Magnetic Interference (EMI) has to address in today's world of computerization where the emphasize is on high band width / high speed along with miniaturization of products . Adverse effect if EMI have increased manifold so all the electrical and electronic products should be Electromagnetically Compatible (EMC). This paper reviews the aspect of EMI/EMC, Standards, testing and control requirement of EMC along with coupling mechanism and adverse effect of EMI/ EMC. We all are aware of a number of pollutions like water pollution, air pollution, sound pollution, etc. These pollutions are well within human perception. But there exists one more type of pollution called pollution of frequency spectrum. It is called Electromagnetic Interferences (EMI). EMI is more erosatic, i.e., it cannot be seen directly, tested, smelled or felt. In today's scenario of computerization, where the thrust is on high bandwidth / high speed along with miniaturization of products, adverse effects of EMI have increased.
Key Words: Electromagnetic Interference, EMI, EMC, Aspects of EMI
[...] Sources of EMI There are three types of sources of EMI: Receptors of EMI Potential receptors of EMI include radio receivers, electronic circuits and appliances, people and just anything that utilizes or detects electromagnetic energy. Propagation of EMI There are two ways for EMI to travel and accordingly it is classified as conducted and radiated EMI. When EMI travels through some physical conductor, it is called conducted EMI. In conducted EMI, the propagation medium is power lines, common ground, or interconnecting cables or data lines. [...]
[...] There are a number of national and international EMC regulatory bodies or standard organizations that are involved in framing standards for different EMC tests for different products. Some of the international EMC standard organizations are: International Electrotechnical Commission (IEC). Based in Geneva, it covers all testing aspects. International Special Committee of Radio Interference (CISPR) Based in Geneva covers emission and some susceptibility testing aspects. Radio Technical Commission for Aeronautics (RTCA) is based in Washington, USA and it covers avionics and aircraft testing. [...]
[...] ELEMENTS OF EMI Electromagnetic interference (or EMI, also called radio frequency interference or RFI) is a (usually unwanted input/output ripple) disturbance caused in a radio receiver or other electrical circuit by electromagnetic radiation emitted from an external source The disturbance may interrupt, obstruct, or otherwise degrade or limit the effective performance of the circuit. The source may be any object, artificial or natural, that carries rapidly changing electrical currents, such as an electrical circuit. EMI can be induced intentionally for radio jamming, as in some forms of electronic warfare, or unintentionally, as a result of spurious emissions and responses, inter-modulation products, and the like. [...]
[...] Source and sink act as radio antennas: the source emits an electromagnetic wave which propagates across the open space and is received by the sink. Coupling mechanism often uses a complex combination of these methods, making the path difficult even when the receptors are known. There may be multiple coupling paths and steps taken to attenuate one path may enhance another. Interference may be radiated from equipment via a number of different paths, depending on the frequency of that interference. [...]
[...] Finally, the Path can be the arbiter of both In any high frequency signal the dominant radiation component under wavelength from the source, is Electromagnetic; this is referred to as Near Field radiation. Any signal beyond wavelength, is Electrostatic, and is referred to as Far Field radiation; sometimes called the Plane Wave. Plane Wave radiation is how radio works and that the 377 ohms is the impedance of free space. In dealing with a Radiation Source it an Antenna or a Circuit Board: The dominant energy in the Far Field is Electric. [...]
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