Price of EMC shielding things, absorbers, ferrite tiles - Page 1
Forum section: electronics / rf-microwave

author: balage
author_rank: Regular Contributor
timestamp: February 07, 2021, 08:34:40 pm
content: Hello,So I am just curious the costs of such EMC accessories. There are absorber for different frequency ranges and in different sizes. Do you have any information?All of the websites have only the button for asking quote.I have that because I cannot even estimate the costs.Thanks,

author: ConKbot
author_rank: Super Contributor
timestamp: February 08, 2021, 06:44:39 am
content: https://www.mouser.com/ProductDetail/Laird-Performance-Materials/78089099/?qs=LzOUtV8FfnZ7J3wQNED9Ew%3D%3DAs bad as you may expect, and then some. Single 2'x2' tile, only good down to 600 MHz, only 17-25 db of loss, $300 plus. The pyramid/wedge foam you see in test chambers is way thicker, and accordingly more expensive. Along with having fire retardants, and protective coatings added.But yeah for a full up treatment with ferrite tiles for low frequency and foam for high frequency, you're looking at thousands of dollars per square meter covered.

author: ahbushnell
author_rank: Frequent Contributor
timestamp: February 08, 2021, 03:03:26 pm
content: Why not a metal enclosure?

author: balage
author_rank: Regular Contributor
timestamp: February 09, 2021, 09:13:13 am
content: Quote from: ConKbot on February 08, 2021, 06:44:39 amWow, I haven't got a clue that Mouser sells such.Yeah then it's true. It's expensive.Quote from: ahbushnell on February 08, 2021, 03:03:26 pmActually I was just wondering how nice would it be to make a room with absorbers for pre-compliance tests. But that is why nobody tries to make shielded rooms for in-house tests.

author: penfold
author_rank: Frequent Contributor
timestamp: February 09, 2021, 10:36:23 am
content: Quote from: balage on February 09, 2021, 09:13:13 amI've seen a number of companies' pre-compliance labs, ranging from small SMPS designer/manufacturers to multi-national defence contractors'... never yet seen a block of absorber material in either! They were however, very nicely screened rooms with top notch filtered power supplies and there was clearly a lot of 'intelligence' going on to make the most of what they had.Its largely application specific however, since most companies Ive dealt with have been power electronic focused, most EMC issues are easily identified from conducted emission and immunity measurements and then ESD to a lesser extent. Moreover its the kind of industry where its possible to just shield the hell out of it so by the time it comes to full RF emissions testing the "cost" of implementing fixes by improving shielding is lower than perhaps a commercial product which doesn't have the profit margin to start including lots of shielding material or changes to the "form" of the product.I seem to remember one or two of the places also had a designated OATS's set up in their carpark!, there was even a fully certified test house who's primary test method was to use a non-accredited anechoic chamber to do an initial sweep which they used to pick up on the top 'n' problem frequencies and do the official measurements on an OATS.

author: mairo
author_rank: Unknown
timestamp: February 09, 2021, 11:16:09 am
content: I think in this thread the OP was saying that the tiles (the good ones they had) were ~$5 a piece (10x10cm).https://www.eevblog.com/forum/testgear/emc-chamber-build-log/see pages 135-136 for ferrite absorb tiles from Samwha:https://www.itacamagnetics.com/wp-content/uploads/2019/09/01-complete-catalog.pdf

author: ahbushnell
author_rank: Frequent Contributor
timestamp: February 09, 2021, 02:41:15 pm
content: https://www.isotechinc.com/radio-frequency-and-electromagnetic-testing-chambers/This is an example of EMI carbon foam in a test bay.

author: DaJMasta
author_rank: Super Contributor
timestamp: February 09, 2021, 07:59:40 pm
content: You can find some secondhand sometimes, but it's generally in small quantities and still reasonably high prices, so it's not so much an option. Assuming you don't need a massive enclosure, the most cost effective way to get it would be buying a secondhand test chamber - you can often find ones from desktop to phonebooth size for sale at auctions and things around (some on ebay too), and while it may not have the exact configuration you're looking for, it's probably going to give you more shielding and absorption than you can get for the same price anywhere else.There have been some discussion of DIY options around here, it's worth a search, but I don't know of substantial results. Some of the most promising looking less expensive things have been the RF absorbing foam sheets designed for use inside devices, but sold in large sheets. Of course these are not going to have the low frequency performance of a proper chamber, but you can certainly deaden reflections in a shielded enclosure substantially.

author: balage
author_rank: Regular Contributor
timestamp: February 10, 2021, 03:27:51 pm
content: It seems that for in-house EMC tests LISNs, near-field probes and a TEM cell are the most common because of the price of a shielded room.

author: penfold
author_rank: Frequent Contributor
timestamp: February 10, 2021, 05:26:24 pm
content: Quote from: balage on February 10, 2021, 03:27:51 pmI think that's generally the case. I would base any decision on what you can buy that will save you money long term, based on the kinds of issues that need repeat visits to the test house.

author: CaptDon
author_rank: Super Contributor
timestamp: February 11, 2021, 08:25:48 pm
content: Local anechoic chamber was over 1.5 million to meet the cert criteria!! The chamber is all steel and even the welds are of different lengths so that nothing can be a resonant sympathetic radiator. The absorber material is a carbon foam HEAVILY coated with a fire retardant!!! IF one of those tips caught fire the fire would spread like kerosene without the flameproofing!!! The cabling enters through pipe welded to the floor for several feet and the instrumentation cable also goes through filtering. The power cabling for U.U.T. goes through heavy filtering prior to the LISN's. The chamber is big, We had an HMMV in there and also some Ford police cars (not at the same time).

author: m3vuv
author_rank: Super Contributor
timestamp: February 12, 2021, 07:48:35 am
content: i dont know if this helps but i often use the copper foil from 18650 cells for shielding,handy as you can solder it.

author: wn1fju
author_rank: Frequent Contributor
timestamp: February 12, 2021, 11:14:44 pm
content: We had a 20'x40' shield room built for us at work about 20 years ago. Steel-plywood-steel sandwich panels bolted together with metal strips. If I remember, the cost back then was about $300K USD. Took one week to build it and three weeks to certify it. All of the metal strips had to be painstakingly shimmed with slivers of copper until the room was completely shielded. It had the usual waveguide-beyond-cutoff passages for ventilation, cable runs, etc. All the power circuitry went through special filters.Ten years later, we decided to make it RF-anechoic. The entire room was coated with ferrite tiles and then the walls and ceilings were covered with anechoic pyramids. The pyramids were basically made of cardboard, but were impregnated with loads of dipole-like fibers. They looked totally harmless to the layman, but take a small piece and stick it into a microwave oven and -poof- instant fire. The only problem with the setup was that the room height was not high enough. This lets the RF inside bounce around at too shallow of an angle to make the anechoic material fully attenuate. The cost for the anechoic addition, including a new Halon fire suppression system, was another $300K.

author: arbstone
author_rank: Newbie
timestamp: April 02, 2023, 08:42:54 pm
content: I'm buying a building in the Northeast US which has 3 Testing Chambers, 26x24 ft, 24x14 ft and 16x12 ft, one of which has ferrite tiles on all the walls plus white/black foam absorbers and a turntable and another with blue foam absorbers/no ferrite tiles/turntable - photos attached.Can anyone refer me to potential buyers for either the entire chambers or the components (ferrite tiles, absorbers, etc)