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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9\$\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 MüllerCommented Dec 19, 2017 at 10:38
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3\$\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 MüllerCommented Dec 19, 2017 at 10:40
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\$\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\$– benCommented Dec 19, 2017 at 10:47
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1\$\begingroup\$ Conducted emissions need a ... conductor. Radiated emissions don't. \$\endgroup\$– user16324Commented Dec 19, 2017 at 11:12
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\$\begingroup\$ @ben are we done here? \$\endgroup\$– Andy akaCommented Apr 4, 2023 at 15:19
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2 Answers
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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.
answered Dec 19, 2017 at 13:04
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1\$\begingroup\$ Big +1 especially for that last sentence. \$\endgroup\$– MołotCommented Dec 19, 2017 at 14:33
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1\$\begingroup\$ I am reminded of a signature; there is no such thing as a digital signal - EMC testing proves this daily. \$\endgroup\$ Commented Dec 19, 2017 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.
answered Dec 19, 2017 at 12:04