Materials for Faraday shield.

[unbuildpain]

I'm trying to make a small Faraday box, so far I've used Brass, Copper and Aluminum mesh, I've used staples to attach them to the wooden frame, I ensured it covered 360 degrees but still signals went through and there was hardly any attenuation. It was not grounded, could that be the reason? Do I need any special material? The mesh wasn't tightly attached to the frame between the gaps of the staples.

There are specially built meshes for EMF shielding which have silver in them, will they fare better than Brass, Copper and Aluminum? They claim it doesn't require grounding to attenuate RF signals.

If the shielding material is made with silver, will it not require grounding?

 

[vfone]

There are two things present in all shields, reflection and absorption, and when combine together produce the shield true effectiveness. When energy is reflected, then some of the energy is absorbed by the shield, and for this reason the shield needs to be grounded.
When the shield is very thin a third reflection factor occurs at the shield far side boundary.
Using a second shield (double shielding) can increase the effectiveness of the shielding by many times compared to single shielding, and grounding may not be necessary. To give an example, a single shielded enclosure using 1.5mm copper sheet could provide about 55dB of shielding, when a double shielded enclosure using the same material could provide more than 100dB shielding.
I don't think silver would make much difference compared to copper when is about shielding.

 

[FvM]

You don't tell which frequency range you want to shield. Openings in the shield metal must be short compared to the signal wavelength. Also any cables running through the shield boundary must be filtered.

 

[unbuildpain]

There are two things present in all shields, reflection and absorption, and when combine together produce the shield true effectiveness. When energy is reflected, then some of the energy is absorbed by the shield, and for this reason the shield needs to be grounded.
When the shield is very thin a third reflection factor occurs at the shield far side boundary.
Using a second shield (double shielding) can increase the effectiveness of the shielding by many times compared to single shielding, and grounding may not be necessary. To give an example, a single shielded enclosure using 1.5mm copper sheet could provide about 55dB of shielding, when a double shielded enclosure using the same material could provide more than 100dB shielding.
I don't think silver would make much difference compared to copper when is about shielding.

What about Aluminum, is it worse than silver, will it work without grounding?

You don't tell which frequency range you want to shield. Openings in the shield metal must be short compared to the signal wavelength. Also any cables running through the shield boundary must be filtered.

Any frequencies possible to be blocked by a cheap box. The copper and brass mesh I have are fine mesh, there are like diaphanous cloth, so their hole sizes would be in millimeter. The holes in the Aluminum mesh was slightly larger, but they should have been able to block microwaves going by the hole size. I checked for FM radio inside a box made out of these materials, there was hardly any signal attenuation, WiFi and 4G also didn't drop. There were no cables running. The radio and mobile phone wasn't touching the material.

How would I filter the cables running through the enclosure?

 

[FvM]

The mesh wasn't tightly attached to the frame between the gaps of the staples.

I suspect the gaps are not tightly connected. Also, is the frame closed on all six surfaces?

It's more effective to use a rigid metal enclosure with a screwed lid. Metal mesh can cover vent openings, connected with a screwed metal frame.

How would I filter the cables running through the enclosure?]I checked for FM radio inside a box made out of these materials, there was hardly any signal attenuation, WiFi and 4G also didn't drop.

I guess the radio has no signal strength indicator, hence you can't determine if you have 10 or 30 dB attenuation.

How would I filter the cables running through the enclosure?

Use power and signal filters with metal flange screwed to the enclosure.

 

[unbuildpain]

I suspect the gaps are not tightly connected. Also, is the frame closed on all six surfaces?

Yes the frame is closed on all six sides, could the gaps have caused allowed so much radiation.

It's more effective to use a rigid metal enclosure with a screwed lid. Metal mesh can cover vent openings, connected with a screwed metal frame.

I guess the radio has no signal strength indicator, hence you can't determine if you have 10 or 30 dB attenuation.

Use power and signal filters with metal flange screwed to the enclosure.

Do you have any tips on how to attach mesh to a metal bar or frame?

 

[FvM]

Brass and copper can be soft soldered to metal bar. Copper tape with conductive adhesive can close shield gaps.

 

[biff44]

use copper mesh, and SOLDER each and every seam. you can not "staple" the ends to a piece of wood! Think of the wood as not even being there as far as RF signals are concerned.

if you are tack soldering or welding one mesh to another, you need a good electrical connection no farther spaced than say 1/10th of a wavelength apart.

 

[unbuildpain]

So I tried a different construction, I made a frame with aluminum tubes, I've attached them with normal screw by drilling holes into them, over this I placed aluminum mesh on all six sides, top, bottom, left, right, front and back and I've attached this with screws by drilling holes through the mesh and onto the frame, the drilled holes are completely covered by the screws.

At few places, the mesh has holes the size of a half centimeter, I've placed a smartphone inside and I called it, and it rang, there was hardly any signal attenuation, I've checked this a signal meter app. I'm unable to understand how the signal could pass through, mesh is also made with aluminum and their hole size is 1mm.

 

[G4BCH]

I would guess that your screws are too far appart making the gaps too long. In my experience the 1/10 wavelength mentioned by biff44 is the bare minimum you need for any signinficant attenuation. Just having the sides in contact is notmuch good either there needs to be signifcant contact pressure. Making a good rf tight seal requires some care. To stop cell phone frequencies, if you can't solder or weld the joints, then a screw about every 10mm or so. If greater spacing adding gasket around the joints will be needed. If you screw the joints together adding gasket is a good idea any way.
As the others have said filtered connectors on any power and control lines will be needed, RF lines should go in and out via coax connectors that make good contact all around the connector.
Screening is not difficult, you just have to be very thorough and not leave any gaps or the RF will find a way through.