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The company I work for needs FCC certification for an electronic product we are designing. I have watched a couple of YouTube videos on the subject but I’m not clear about the difference between the conducted and radiated emissions tests. If someone could explain the differences that would be great.

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    \$\begingroup\$ watching Youtube videos as a designer of electronics that need certification being an accepted way of research... I don't like this timeline. In other words: Please research with reputable sources. The FCC has a website. \$\endgroup\$ – Marcus Müller Dec 19 '17 at 10:38
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    \$\begingroup\$ also, "conducted" and "radiated" are English words, and their meaning in electronic emissions follows exactly their usual, "dictionary" meanings. So, one is conducted, the other is radiated. \$\endgroup\$ – Marcus Müller Dec 19 '17 at 10:40
  • \$\begingroup\$ @MarcusMüller so conducted is the emissions coming out of the wires from the product and radiated is something like the radio waves the product emits ? \$\endgroup\$ – ben Dec 19 '17 at 10:47
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    \$\begingroup\$ Conducted emissions need a ... conductor. Radiated emissions don't. \$\endgroup\$ – user_1818839 Dec 19 '17 at 11:12
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So-called "radiated emissions" are picked-up with a test-antenna and can come from all parts of the product INCLUDING the cables it uses (power and module interconnects).

Conducted emissions are measured directly as voltages or currents on the cables used by the product. Testing done on power cords is achieved by using a LISN.

Many times, signals that are within the limits for conducted emissions may radiate from cables and become problems as radiated emissions.

I’m not clear about the difference between the conducted and radiated emissions tests

Nothing in EMC is totally clear-cut.

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    \$\begingroup\$ Big +1 especially for that last sentence. \$\endgroup\$ – Mołot Dec 19 '17 at 14:33
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    \$\begingroup\$ I am reminded of a signature; there is no such thing as a digital signal - EMC testing proves this daily. \$\endgroup\$ – Peter Smith Dec 19 '17 at 15:30
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The difference between conducted and radiated emissions is exactly what the words say.

Radiated emissions is radio energy radiated by the unit. Something in the unit makes high frequencies, and something else acts enough like a antenna to radiate some of that power into space.

Conducted emissions are conducted away from the unit by wires attached to it. If your unit is completely self-contained, like a battery powered portable radio for example, then there is no issue of conducted emissions.

Conducted emissions are usually measured on the line cord. This is one reason you can buy off the shelf line power filters. Your switching power supply may cause all kinds of high frequencies to be conducted back along the line cord, but a filter is supposed to block and shunt enough of that so the what still makes it to the line cord is below the legal limit.

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