Can a Faraday Cage Effectively Shield Against 13.56 MHz RF Interference?

[aliaze1]

I'm working on a project that has a 13.56 MHz RF power source. The thing is, the EM waves emitted by this power source cause problems with the diagnostic equipment of the actual experiment (various capacitive and inductive sensors). So, I am planning to build a faraday cage to shield the source as to reduce the interference level.

I searched the forums and it seems that as long as the mesh of the cage is less than a wavelength, it will do a decent job. Using the folrmula λ=v/f , I get 3*10^8 / 13.56*10^6 = ~22.1 meters...so if I understand this correctly, if I make a wooden cage (like a plastic carton) and space metal mesh cables about a foot apart into a grid on the wooden frame (making 1 sq ft openings), that would do the trick?

Also, please help me understand the underlying theory behind this one wavelength thing.

Thanks!

 

[berkeman]

I'm working on a project that has a 13.56 MHz RF power source. The thing is, the EM waves emitted by this power source cause problems with the diagnostic equipment of the actual experiment (various capacitive and inductive sensors). So, I am planning to build a faraday cage to shield the source as to reduce the interference level.

I searched the forums and it seems that as long as the mesh of the cage is less than a wavelength, it will do a decent job. Using the folrmula λ=v/f , I get 3*10^8 / 13.56*10^6 = ~22.1 meters...so if I understand this correctly, if I make a wooden cage (like a plastic carton) and space metal mesh cables about a foot apart into a grid on the wooden frame (making 1 sq ft openings), that would do the trick?

Also, please help me understand the underlying theory behind this one wavelength thing.

Thanks!

I believe the general rule of thumb is more like 1/10 of a wavelength. Where did you see the full wavelength suggested?

How big does the box need to be? I'd go with solid sheet stock for the best results, unless it's a really big box.

You need to pay a lot of attention to seams, any access ports, electrical feedthroughs, etc. Any access ports should have conductive gaskets on the door seams, which seal with good compression when the port is closed.

I'll see if I can find a tutorial on constructing shielded enclosures...

 

[berkeman]

The wikipedia intro article is not bad. Be sure to check out some of the links at the bottom:

http://en.wikipedia.org/wiki/Electromagnetic_shielding

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