RF Shielded Lab

[stern0m1]

Hi,

How can I setup a testing environment (on a budget) that would be totally shielded from wifi rf?

I tried using a stainless steel box, I even connected it to ground from an outlet, but it still picked up wifi.

I need to test an esp8266 in promiscuous mode. (Don't shoot me Felix for mentioning esp8266. 

Thanks

[john4444]

Hi Stern0m1,
It is not possible to totally shield from RF.
However, as a practical matter, an RF signal can be attenuated to the point it is not detectable.
Stainless is not a great shielding material due to its moderate resistance.
Practical RF shielding often uses brass screening (found at the hardware store).
If you were to make a rectangular, 6-sided enclosure from screening, each cut edge of the screening
needs to be securely soldered to the edge of the other sides to provide a low resistance connection.
Also, be aware that it can be very difficult to prevent RF from entering via any connections from the
inside to the outside of your enclosure such as wires to power your esp8266.

Good luck

[stern0m1]

Something like this?
https://www.amazon.com/AMACO-WireForm-Metal-Impression-Copper/dp/B0027IZCB0/ref=pd_sim_201_8?_encoding=UTF8&psc=1&refRID=4Y64PAVX18J8ZVS06441

Thanks

[ChemE]

I know this sort of stuff as "expanded metal mesh" as here: http://www.brasswiremesh.net/brasswiremesh/expanded-metal-mesh.html

I use it for wildly different purposes but I suspect the terminology carries over.

[Neko]

I've built Faraday cages (to shield from RF) on many occasions and usually use copper screen that has a mesh size about the same as a window screen. So something like the 10x10 mesh size on this page from McMaster.

It's very effective and nicer to work with than the stuff you link to. As noted above, connect all the sides electrically and ground the whole thing. If you're going to be using something over a long time period and want to make it durable, I would make a nice solid support frame with pieces of 80/20 or similar.

Or, if you've got the budget and don't have the time, you can buy a complete Faraday cage here or here.

And finally, here's a small plastic enclosure that's coated with EMF shielding.

[stern0m1]

Is there anyway I can have wires sticking out and still block rf?

[ChemE]

Can they stick out and still be in wire-shaped Faraday cages?  Pretty sure that is what shielding actually is right?  Would it be as easy as connecting shielding to the cage itself?

[Neko]

Right. Wires coming out of the cage can be shield (coax). You can try to use unshielded wires. But they will act like antennae (antennas?) and bring the RF inside. Depending on where they end up in your circuit, they could have an effect or not.

[stern0m1]

My objective is to control the wifi frames received by an esp8266. The esp8266 in promiscuous mode picks up everything, not just what's directed to it. I don't care if the circuitry picks up some random rf noise.

I'll try with the copper mesh.

Thanks