How Do I Build a Faraday Cage?

Jea48 is right - no grounding needed. We do it in the lab all the time. All you need is a sheet of copper that encloses the unit. If you ever visit radio telescopes, you will see that they line the entire data room with copper foil. Also, bust open a cell phone and you will find the same.

Also, many new switching circuits have a sheet of ferrite polymer that simply sticks down on the surface of the PCB. Ferrite works better than copper at lower frequencies actually (e.g. 60Hz line frequency and multiples thereof) but both sandwiched together gets you even better supression (copper on the outside).

Arthur

As Bgrazman points out the cage does not need to be a solid sheet of conductive material. A wire mesh with quite wide wire spacing works fine. Indeed, your metal car provides good protection from lightning strikes even though it has large openings for windows.

Also, as Jea48 points out, grounding is not necessary, although it might be a good idea if only for safety reasons. When I installed shielded 300 ohm twinlead wire from a roodtop FM antenna I was surprised to find that the shield, for which I had paid extra $, was left unconnected at both ends. Seemed like a waste, but it worked great for eliminating interference from passing auto trafic.

Try going to Office Depot and look for the new style "mesh" office products (letterholders, wastecans, etc).. You may find what you need to cover whatever it is that you need to set up a field around your equipment. Stopping extranious waves is a matter of stopping whatever wavelength(s) is causing the interference. You may need to eventually try some copper shielding postioned or vectored within the wavepaths.
Remember, WL (wavelengths) are not only absorded, they also bounce. what you may stop, may richocette and enter from another angle.

Good Luck,
Tubby

Just found this thread, as yesterday I first ran into the idea of a faraday cage. I have just ordered some more Stillpoints ERS sheets, but I think a larger difference was made when I covered my audio magic power conditioner and placette preamp entirely in aluminum foil, with serious results for each. I think they are just plastic boxes without any metallic barrier on the inside to protect the bare wires on the inside. In that case, shielded cables has only done half the job, becuase inside the components everything is basically open. These "treatments" really allow ambient details and the correct timber of musical notes to appear, which were previously obscured. My guess is that AL foil is reflecting more of the airborne rfi, while the ERS sheets are better served on the inside of components to absob RFI from everything attatched to the cicuit boards or also around cables. I'm still trying to discover where the ERS sheets work best though, just got them a week ago. I may cover all my equipment with foil soon though unless I can find some metal cages of various sizes.Should I also cover the bottom of the walls of my room with foil along where the power lines run?
Any thoughts or recent revelations out there?

If you want it to work OPTIMALLY, you need to use thicker materials that are solid. The cage would also be attached to a low resistance Earth ground. Aluminum is FAR less desirable than steel and to a lesser extent, copper.

Using thinner materials that aren't solid i.e. metal screening, etc... that lack a low resistance path to Earth ground can also produce beneficial and highly usable results. How well you want it to work and how much you want to spend may dictate certain cost-cutting techniques to be implimented. Such are the design variables that any project / product encounters. Sean
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PS... Don't forget to address cabling coming in and going out of the device as these can act as EMI / RFI conduits also.