EMC Chamber - Page 1
Forum section: electronics / projects

author: podericof
author_rank: Newbie
timestamp: September 11, 2025, 02:27:38 pm
content: I’ve started building my own EMC radiated emissions (RE) chamber — 70 × 70 × 120 cm — and just ran the first test. I’m honestly chuffed with the results:Noise floor is almost ideal ✅There’s a cheeky RF ingress around ~660 MHz that I’ll tame in the next day or two 🔧This gives me another powerful tool to help customers debug and fix EMC faster, without waiting on external lab slots.I'm designin the dront door now.AC filter will be outsite, but I haven't decided yet how to bring AC inside without "breaking" the shield

author: TimFox
author_rank: Super Contributor
timestamp: September 11, 2025, 07:47:12 pm
content: I remember using a large RF shield room (for a full size MRI scanner) where one set of line filters on the outside fed another set of line filters inside the wall. The metal cases of the filters blocked the holes that cleared the wires connecting them.

author: HS Zhang
author_rank: Newbie
timestamp: September 22, 2025, 12:16:43 pm
content: Looks great! The spectrum looks exist GSM band noise, does the chamber case grounded well? And do you pasted ferrite absorber inside of the chamber?

author: DavidJRobertson
author_rank: Regular Contributor
timestamp: October 15, 2025, 04:05:34 am
content: Having been made to use an unlined chamber for in-house tests, I'd be really shocked if you're able to get results from that setup that can be meaningfully be correlated to proper EMC lab results.

author: Whales
author_rank: Super Contributor
timestamp: October 15, 2025, 04:16:44 am
content: NiceI assume the inside walls are purely metallic, ie reflective? Make sure to move your antenna about during testing or you might be unlucky enough to be sitting in a nullpoint for the freqs you care about.What antenna are you using? I assume the best spot to mount the antenna would be directly in a corner, because this minimises the reflection paths. Alas it will also detune antennas designed for free space, but for all I know you're just using a monopole.

author: makebit
author_rank: Unknown
timestamp: October 15, 2025, 07:35:50 am
content: Would be good to compare results with a TEM cell...https://www.theemcshop.com/anechoic-chambers/gtem-cells-tem-cells/

author: bookaboo
author_rank: Frequent Contributor
timestamp: October 15, 2025, 11:08:53 am
content: QuotePerhaps not in absolute terms , but it's still very useful to have something like this or a TEM Cell for relative measurements.(a) Sanity check for seeing anything that's really out of bounds.(b) For doing same/better/worse experiments(c) Debugging fails from accredited EMC chambers, you know the frequency of interest so can work on reducing the relevant peaks.

author: DavidJRobertson
author_rank: Regular Contributor
timestamp: October 15, 2025, 08:34:36 pm
content: Quote from: bookaboo on October 15, 2025, 11:08:53 amA TEM cell is something entirely different to this.For B and C, yes it may be useful. For A it probably won't be unless you can somehow characterize the chamber.We have a walk-in chamber without RF absorber (just a big metal box effectively, almost but not quite big enough to get 3m separation from antenna to EUT if the EUT is small and gets shoved in the corner). Comparing the spectra measured in that chamber to those from the same EUT in a real EMC lab's semi-anechoic room, it's totally unrecognizable. It's not just a scaling problem. The peaks and nulls of the chamber completely change the spectrum.Also, at this scale you're seeing near field effects.

author: joeqsmith
author_rank: Super Contributor
timestamp: October 15, 2025, 09:09:26 pm
content: Quote from: DavidJRobertson on October 15, 2025, 08:34:36 pmStirrer?