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DIY Faraday cage

paulie102003 Jun 15, 2019

  1. paulie102003

    paulie102003 Registered User

    So picked up my S5 yesterday (no pictures yet but I will get it sorted) however worringly, the dealership wasnt sure if it had keyless entry or not. It does and so I decided to build myself a faraday cage and thought I would document how I did this in case anyone else wished to follow. This is easy, quite cheap, cost me about 20 quid in parts and a few hours of time and is better than those horrible bags that you can buy off certain websites. And yes I know that this doesnt stop anyone breaking into your house - the reality is that if they want your car, they will take it.

    I wanted something nice and easy to just throw the keys into at the end of a day, something which will look half decent and not too much like an afterthought, and I hate those bags. So I ordered a cheap wooden box off the internet for a fiver which is about 200mm x 200mm x 150mm tall. Internal dimensions, now, are about 140mmx140mmx90mm. I need to stain it with an oak stain that I have lying about however this is not done as of yet.

    The box is a simple pine construction, however it was completely empty. I created an interior wooden frame to force the lid to seal down tightly onto it as per this picture.

    20190615_113601.jpg 20190615_113618.jpg

    After a lot of sanding, I got it to seat nicely, so a solid push seats it, and a gentle tug releases it.

    It is best to use copper mesh as copper is really conductive of radio signals, however aluminium works ok, and its quite expensive to order pure copper mesh even from the internet. (Try wrapping your key in aluminium foil and it will block all signals). The basic science behind this is that keyfobs work on approximately the 300mhz range, which is a wavelength which is quite small in size. As it is on the UHF range (ultra high frequency), it can go all the way to approximately 3ghz. The size of these wavelengths are called Decimeters and all frequencies within the UHF range fluctuate from between 1 to 10 decimeters, which, in English, means the size of the wavelength are between approximately 10mm to 1000mm from their peak to their troughs. If these wavelengths are interrupted at any point, the signal fails. So, put a conductive barrier which is less than 10 mm in size, it will interrupt the wavelengths and therefore any signals, meaning they cannot be high jacked.

    So, I lined the box with 3 layers of insulation foil, freshly stolen from the ex wifes kitchen drawer. On top of that, I cut and layed 5mm aluminium mesh on the bottom of the box, and on its sides, making sure that I overlapped them by a couple of inche and held in place with some wood staples. I layed 2 layers of mesh, overlapping the holes inbetween the mesh to make it even tighter.


    The lid was removed and I created a lip within the lid, to ensure that it would contact with the raised lip on the base and make it as tight a fit as possible, packed it with foil and sealed it.

    20190615_141254.jpg 20190615_142519.jpg 20190615_145753.jpg

    This then received the same treatment as the base.

    A quick trip, down some country lanes in Dynamic mode to my local Hobbycraft to pick up some foam and felt sheets so I could tidy the inside up a bit. The foam was sprayed with contact adhesive onto the mesh/foil, to create a more solid base for the felt. At this stage, the box already worked, I was just tidying it up.

    20190615_155652.jpg 20190615_161600.jpg

    It needs a bit of tidying up and staining however, it now looks like this - a nice place to just throw the keys in after you get home and not worry about any relay attacks. And most importantly, it works - sit in the car and it hasnt got the faintest clue the fob is there

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  3. RAF_S7

    RAF_S7 Well-Known Member Gold Supporter

    Very nice, you're obviously a craftsman at heart.

    For those of us not so inclined, there's always the microwave and a Tupperware box. :racer:
    CHEZ, Scotty75, Bristle Hound and 3 others like this.
  4. V6_Man

    V6_Man Moderator Staff Member Moderator VCDS Map User

    Blo*dy fantabolous. Like @RAF_S7 mentioned above your attention to detail and craftsmanship is amazing. Hats off mate
    Last edited: Jun 15, 2019
  5. Bristle Hound

    Bristle Hound Moderator Staff Member Moderator

    Very impressive !

    Being lazy & a bit of cheap skate I would go for these myself ...
    Scotty75 and V6_Man like this.
  6. MuPPeT_ON_TouR

    MuPPeT_ON_TouR Well-Known Member Silver Supporter

    I like the box idea for at home but find it easier to hide a bag of keys at home.

    Breaking in and stealing the car keys and other items from you house to get the car is still as high on the list as relay attacks.

    I also find it easier to take the little bag with me if we go away as cars are not just stolen from your drive way.
  7. B5NUT

    B5NUT Well-Known Member VCDS Map User

    I would stick a big sticker on it like "car keys" if these guy's want your car then they will break in and could threaten you & your family for the keys. I have done a similar trick with my car keys, I use a nice steal box to put them in, but it's well labeled and on top of the fire place so if they want the keys they can just take them. I'm just trying to stop the lower end of the scum, the higher level of scum that are willing to break into the house can just have the keys/cars they are not worth my family.
    oli356 and paulie102003 like this.
  8. terminator x

    terminator x Registered User

    Can't agree, the relay attack guys just want easy to steal keyless cars. If the car won't open after a short while they will simply go next door and try there.


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  9. B5NUT

    B5NUT Well-Known Member VCDS Map User

    Plenty of people have been broken into for car keys, yes it stops the relay attacks which is what I have done, but I don't hide the box the keys are in. It's like this stupid advice https://www.dailymail.co.uk/news/article-183611/Take-car-keys-bed-say-police.html If they are willing to break into the house they can have the keys & the car, my family is far more important than a lump of plastic & metal.
    paulie102003 likes this.
  10. paulie102003

    paulie102003 Registered User

    I must agree, its a mild deterrent for those lower end criminals who stand on your driveway - at the end of the day, thats why we pay stupid amounts of money to insurance companies to cover events like this. For me, there is no tangible value which I can place on the security of my kids - they are genuinly priceless to me. Now the ex wife however..... anyone got a spare fiver?
    oli356, B5NUT and V6_Man like this.

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