EMC INFORMATION
WHAT IS EMC?
Plastic Box , Plastic Box , Plastic Waterproof Enclosure , Hand-held EnclosureElectroMagnetic Compatibility: With the proliferation of electronic systems in every aspect of our daily lives, there inevitably comes the problem of compatibility. Listening to the news on AM radio while using an electric razor should not be a problem, as it was in days gone by.
WHY DO WE NEED EMC?
If EMC design practices are adhered to by both the razor and the radio manufacturers, then listening to the news on an AM radio, while using an electric razor, presents no problem.
Also, worldwide governmental regulations prohibit electronic products from emitting or being susceptible to, Electro-Magnetic Interference.
HOW DO WE IMPLEMENT EMC?
Emission, Susceptibility, and Path are the three constituents of EMC, with Emission being the one causing the most incompatibilities, while yielding the greatest number of solutions. Susceptibility on the other hand, is more subtle in its effect and its solutions. Finally, the Path can be the arbiter of both.
DISCUSSION:
EMC can be approached in two ways: before the fact-designing for EMC; or after the fact¡ªpatch work/clean up, Band Aids. Of course, designing in EMC safeguards ahead of time is always best; however, sometimes even the "best" designs aren't enough, and require some Band-Aids. Thus the "ART" aspect of EMC.
With the proliferation of electronic systems in every aspect of our daily lives, there inevitably comes the problem of compatibility. Listening to the news on AM radio while using an electric razor shouldn't be a problem, thanks to EMC design practices on the part of the razor manufacturer.
The three constituents of EMC are [unwarranted] Emissions,[inappropriate] Susceptibility, and the [unintended] Path between them. The electric razor's motor brushes arcing is a case of unwarranted Emissions; and the AM radio's picking up the noise through the Path(s) (power line, and/or through the air), is the unnecessary Susceptibility.
Block Diagram Depicting the EMC Paradigm
Path consists of Radiated and Conducted energy.
1. Radiated (electromagnetic field)
2. Inductively coupled (magnetic field)
3. Capacitively coupled (electric field)
4. Conducted (electric current)
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Near Field, Far Field Radiation
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In any high frequency signal the dominant radiation component under ~1/6 wavelength from the source, is Electromagnetic; this is referred to as Near Field radiation. Any signal beyond ~1/6 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. | ||||||
The dominant energy in the Far Field is Electric. 
The dominant energy in the Near Field is Magnetic. 
