Testing Phone-Sized Faraday Bags
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Testing Phone-Sized Faraday Bags
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Re: Testing Phone-Sized Faraday Bags
#2That was really interesting. I can’t believe how poorly the metal tin box did compared to real faraday pouches.
Re: Testing Phone-Sized Faraday Bags
#3That was really interesting. I can’t believe how poorly the metal tin box did compared to real faraday pouches.
The metal tin box will have had varnish and paint on it's surfaces.
That means at the junction between the tin and the lid (and maybe other joins), there isn't an electrical connection all along.
Having two metal surfaces next to eachother, but with an insulator in between, acts like a 'choke flange'[1]. However, they only work at one specific frequency - at all other frequencies they will leak either a little signal or a lot/all the signal.
The same technique is used on a microwave door edge to keep the microwaves in. It's why keeping the microwave door edge clean is critical to safety - a small bit of food there isn't an insulator like the paint, and energy leaks out.
[1]: https://en.wikipedia.org/wiki/Waveguide_flange#Choke_connect...
Re: Testing Phone-Sized Faraday Bags
#4Cheap science fiction book idea: imagine having to choose between living without your smartphone or living with every company and government agency willy-nilly spying on you. Oh, wait...
Re: Testing Phone-Sized Faraday Bags
#5Wrapping your phone in aluminum foil also works.
I've made a few DIY Faraday bags that way. They're not perfect of course, but less expensive than these bags most of the time.
Edit: Ah, I see this was covered in the article. I didn't read it before posting this comment.
Re: Testing Phone-Sized Faraday Bags
#6Wrapping your phone in aluminum foil also works. I've made a few DIY Faraday bags that way. They're not perfect of course, but less expensive than these bags most of the time. Edit: Ah, I see this was covered in the article. I didn't read it before posting this comment.
It also keeps them from drying out when you microwave them while still maintaining a crispy skin.
Re: Testing Phone-Sized Faraday Bags
#7At my former job we had a rather large faraday cage for testing telco equipment. Two things surprised me: 1) It is more fiddly to ensure a room-sized faraday cage doesn't leak RF than I thought. It is really easy to make mistakes that compromises experiments. 2) There was a bath-towel sized piece of cloth that came with one of the expensive Rohde & Schwarz instruments that was astonishingly effective at blocking signal.
So I mainly used the room because that's where the magic blanket was - which was easier to use than ensuring the room was set up correctly.
Re: Testing Phone-Sized Faraday Bags
#8> While the cookie tin performed much better than the mylar bags, and could provide a modicum of useful attenuation under some circumstances, it was not sufficient to provide meaningful assurance of signal isolation at any frequency. However, it was unique among the containers tested in providing tasty snacks during measurements
Back in the day working for Symbian I used to regularly have to run a load of automated Bluetooth tests. Unfortunately there were 200+ engineers in the close vicinity of my test setup and they all had smartphones and all had Bluetooth turned on, causing loads of the test to timeout. We were very pleased with ourselves when we thought of using a biscuit tin as a Faraday cage to try and improve things. Didn't work as well as we hoped, but got the tests running within their timeouts. I always thought it'd be interesting to try using an old microwave.
Best thing was that we got to eat all the biscuits first :)
Re: Testing Phone-Sized Faraday Bags
#9Perfect timing, I was just looking up this topic in the last week.
But how come these are all US-exclusive. It seems both winners don't ship to EU :/
Re: Testing Phone-Sized Faraday Bags
#10My understanding is that a Faraday Cage, of any size, relies on a proper grounding system to work at all so these boxes and rfid blocking pockets etc all seem to be tinfoil hats parading as space age metamaterials.