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Seeking Help
If you are unable to reduce emission levels to the specified standards and
your product fails its compliance test, you may want to seek professional
help. There are many qualified consultants and laboratories that are prepared
to assist you by providing guidance and expertise in solving the emission
problems of a product.
EMC101
Why EMC?
In order for electronic products to be sold, it needs to satisfy local
government regulations limiting the amount of electromagnetic emissions
(radiated and conducted) it produces. Radiated emission is caused by the
product acting as a radio station, emitting byproducts of its internally
generated electrical signals. Conducted emission consists of high-frequency
signals superimposed on cables connected to the product. Excessive
electromagnetic emissions may interfere with the normal operation of other
products. Locating the sources of such emissions can help to restore normal
operation. The 3M
™
ScanEM-QC Electromagnetic Near-Field Probes deal
with both radiated and conducted emission.
Near-Field Primer
The measurements done for agency approval are performed at a distance
of three to ten meters. At these distances, the nature of the electromagnetic
field is determined by the source and the distance from the source. As the
test antenna gets closer to the source, the nature of the electromagnetic field
changes. Near the source of radiation, the field produced is mostly a function
of the properties of the source. If the field is generated by an object with high
current and low voltage, the field produced will be magnetic in nature, or
H-field. If the source has high voltage but little or no current, the resulting
