Electronics > RF, Microwave, Ham Radio

RF shielding enclosures

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VSV_electron:
I tried to collect some meaningful information on making DIY shielding boxes for basic RF experimental circuits and I can't find any definitive guides on how to make them. Every book on amateur RF circuits mentions them as an absolute must but none goes into any details on what metal to use, what wall thickness etc.

I went through some online one-page primitive articles and they suggest to use copper and brass for RF shielding. Some threads on EEVblog suggest using 0.3 mm copper sheet for DIY enclosures, others suggest nickel silver sheets.

What about stainless steel which is often readily available for DIY? It's probably not as easy to solder to the ground plane of the PCB compared to copper and brass?

Anyways, please give me some guidance on how to make decent DIY RF shielding enclosures for a wide range of the unwanted interference frequencies when designing basic RF circuits.

xrunner:
You can use conductive copper tape with a plastic enclosure and it works very well. I recently finished an RF power meter using this type of shielding and it worked perfectly fine. You can buy the copper tape with conductive adhesive on Amazon or perhaps other suppliers.

biastee:
Test equipment casings are universally aluminium - probably for weight saving. Car radios are steel.

Among hobbyists, sometimes PCB is used - see this Hackaday and qrpbuilder articles. However, the two aforementioned articles don't address the question of seams at the lids / covers which I feel is very critical: copper tape as gasket for PCB enclosure

I haven't seen stainless steel being used. Its rarity is probably due to it being more expensive and requiring special tools to cut & drill. 

In making RF proof enclosures, you want to pay attention to the degradation caused by seams (lids) & apertures (knobs & display, etc). My go-to reference is Chatterton & Houlden, EMC, particularly its chap 4 which describes testing methods for shielding,  equations for apertures and a graph for different seams / joints.

radiolistener:

--- Quote from: VSV_electron on May 16, 2024, 01:50:53 am ---I went through some online one-page primitive articles and they suggest to use copper and brass for RF shielding. Some threads on EEVblog suggest using 0.3 mm copper sheet for DIY enclosures, others suggest nickel silver sheets.

What about stainless steel which is often readily available for DIY? It's probably not as easy to solder to the ground plane of the PCB compared to copper and brass?

--- End quote ---

Such things are explained in books about shielding theory, include formulas, so you can estimate your case.

It depends on specific case: frequency, near or far field noise source, which near field is more critical - E or H.

Regarding to steel, I don't remember exact frequencies, but at some frequencies and conditions steel material can be better than copper. But in most cases copper is better.

pdenisowski:

--- Quote from: VSV_electron on May 16, 2024, 01:50:53 am ---I tried to collect some meaningful information on making DIY shielding boxes for basic RF experimental circuits and I can't find any definitive guides on how to make them. Every book on amateur RF circuits mentions them as an absolute must but none goes into any details on what metal to use, what wall thickness etc.

Anyways, please give me some guidance on how to make decent DIY RF shielding enclosures for a wide range of the unwanted interference frequencies when designing basic RF circuits.

--- End quote ---

As @biastee stated, in most cases it's the seams / seals that you need to pay special attention to.  At higher frequencies, even very small gaps can act as slot antennas (i.e. if wavelength is shorter than the size of the aperture), so it's important to know what frequencies you are looking at. 

Also, unless your device is completely self-contained / battery-powered and requires no interaction with the "non-shielded" world (control lines, etc.), any penetrations made in your enclosure for passing wires, etc. through will also compromise shielding effectiveness to some degree.

It's also not clear (to me, at least - sorry :)) from your post if you are trying to stop signals from entering or keep signals from leaving the enclosure: depending on your use case, the required attenuation might be considerably different.  With regard to seams, conductive tape is often very cost-effective if your shielding requirements are modest.

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