Good advice. --
Ken Javor Ph: (256) 650-5261 On 2/14/25, 1:59 PM, "Ralph McDiarmid" <rmm.priv...@gmail.com <mailto:rmm.priv...@gmail.com>> wrote: Hi Amund, RF ambient signals are generally narrow band signals, like television and radio broadcast frequencies. It may be possible to identify those by measuring the ambient, turning on the EUT, and measuring again. That is what certified OATS (open area test sites) do routinely. Building or buying a shielded room is a major investment in test infrastructure. If you plan to do a LOT of radiated emission pre-compliance testing, then the investment should pay-off, eventually. Having a decent in-house radiated emissions test set with antennas and a decent SAC (semi-anechoic chamber) is a major capital equipment plan but it can be cost beneficial over a long term. (considering the time and the cost per hour at a local EMC test company ) I recall a discussion thread not long ago on this forum addressing reflected signals in a shielded room and the need for pyramidal RF absorbers or ferrite tiles to minimize those reflections and the measurement uncertainty they can cause. Again, a significant capital investment in a decent indoor test facility which might pay off in a year or two, depending on how much of this kind of testing you plan to do inhouse. I have found that in almost every case, reducing CM currents on power and on signal cables connected to the EUT improved the radiate emissions significantly. Rarely, was the radiated emission problem the result of RF leaks at ventilation openings or long seams on the EUT enclosure. So perhaps an investment in an RF absorber clamp to qualitatively measure those common-mode currents on cables would get you most of the way to a solution. You'll still need to visit an EMC lab once or twice as you converge on a final, compliant design. Ralph -----Original Message----- From: Amund Westin <am...@westin-emission.no <mailto:am...@westin-emission.no>> Sent: February 14, 2025 3:02 AM To: EMC-PSTC@LISTSERV.IEEE.ORG <mailto:EMC-PSTC@LISTSERV.IEEE.ORG> Subject: [PSES] Faraday tent For in-house pre-EMC testing (radiated emission), ambient noise gives us problems. Anyone who have experience with using faraday tents? Best regards Amund - ---------------------------------------------------------------- This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. 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