AN898 Datasheet, PDF (3/4 Pages) STMicroelectronics – EMC GENERAL INFORMATION

EMC GENERAL INFORMATION
2 EMC REGULATIONS
Regulations are one of the primary reasons we test products for EMC. Therefore, we will now
look at some of the important organizations that develop and enforce EMC regulations. Failing
to comply with EMC regulations can result in forced removal of a product from the market
place or even monetary fines.
Figure 3. Conducted versus radiated Regulations
CONDUCTED
30 Hz
450 kHz _FCC 30 MHz
9 KHz
EN
30 MHz
MIL-STD
40 GHz
RADIATED
30 Hz
30 MHz
FCC ^40GHz
9 kHz
EN
1 GHz
MIL-STD
40 GHz
FCC
Federal
Communications
Commission
EN
European Norms
MIL-STD
US Military
Norms
1 Hz
1 kHz
1 MHz
1 GHz
Frequency (Herz)
VR02102C
EMC regulations cover the entire spectrum of electrical products, from computing equipment
to microwave ovens to aircraft. As shown, the frequency ranges of interest for EMC testing ex-
tend from 30 Hz to 40 GHz (9 orders of magnitude), depending on the agency and the type of
measurement. The frequency range over which regulations exist varies, depending on the de-
vice and its intended use.
While individual EMC requirements vary widely from one another, one common aspect is the
goal of achieving valid, repeatable results. Therefore, most regulations specify the test envi-
ronment, receiver and transducer characteristics. Antenna height and polarization is usually
varied, and the tested equipment is rotated to find the maximum response from the device. All
these actions help insure that the worst-case emissions are found.
Because so many factors affect emissions, an environment with known characteristics must
be used when measuring electromagnetic interference. Testing within a known environment is
critical in order to assure meaningful and repeatable results that can be compared to other
measurements performed on other devices.
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