Electronics > RF, Microwave, Ham Radio

Faraday cage from an old microwave oven

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jonovid:
gutting the electronics from an old microwave oven. you get this- .
the steel microwave oven case is lightweight without the hefty power transformer.
also the door catch mechanism remains intact.
removing the glass from door and the clear plastic film sheet from the inside of the door  see image.
with the steel door panel clear of its glass . modifications can be added to it.

as a faraday cage a plywood shelf can be added to the inside of the oven door to hold any RF project with any panel mount BNC connectors in the door itself.             
the steel microwave oven cover can go back on.  whatever works best.

Ian.M:
The problem with that is the door EMI seal is a frequency specific 2.45 GHz half-wave choke. https://www.edn.com/your-microwave-oven-needs-a-choke-flange/

For frequencies where the door diagonal is a very small percentage of the wavelength, its probably good enough if the door is reliably grounded via its hinges, but unless you upgrade the door seal with a conductive elastomer gasket, on bare metal, contacting a bright-plated bare metal mating surface, it wont be a good Faraday cage for high frequency work.

Also why mess with the door to add feedthroughs etc. when you've already got the waveguide opening into the cavity? 

jonovid:

--- Quote from: Ian.M on March 21, 2024, 09:19:56 am ---The problem with that is the door EMI seal is a frequency specific 2.45 GHz half-wave choke. https://www.edn.com/your-microwave-oven-needs-a-choke-flange/

For frequencies where the door diagonal is a very small percentage of the wavelength, its probably good enough if the door is reliably grounded via its hinges, but unless you upgrade the door seal with a conductive elastomer gasket, on bare metal, contacting a bright-plated bare metal mating surface, it wont be a good Faraday cage for high frequency work.

Also why mess with the door to add feedthroughs etc. when you've already got the waveguide opening into the cavity? 


--- End quote ---

putting the steel microwave oven cover back on would give the faraday cage a flat top so
test equipment can sit on top of it saving bench space.
the waveguide opening into the cavity is on the side so hard to reach when setting up a project? so requiring a steel plate over the waveguide opening.
also requiring a hole to be cut in to the side of the steel oven cover with a rubber weather strip covering the sharp edges of the hole.
looks like your right this is not a cheap and simple DIY   :palm:

Ian.M:
Hmmm.  Flexible conduit in a swept bend to the front control panel area from the waveguide opening, and add four studs round the waveguide opening to fit a plate with thru-connectors from the inside of the oven, clamped down on a conductive gasket using wing nuts?

You'd make up a project specific cable harness and plate, and hook the cables through the conduit using some sort of flexible grabber or similar.

That still leaves the problem of retrofitting an EMI gasket to the door.

radiolistener:
what is purpose for that "Faraday cage"?

You can get large metal saucepan with lid for the same volume

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