DIY Ultralight 'Faraday Cage' RFID Blocking Wallet
There has been a surge of new RFID blocking wallets and other products on the market that are designed to block cellular phone or RFID chip signals in order to prevent their transmissions or stored data from being maliciously intercepted, scanned or used to track your location. Two recent examples of these types of products that spring to mind are the LOKSAK ShieldSak ($33) and the Nemo EMFX-47 Pouch ($50).
Radio frequency identification (RFID) chips hold personal information, which can apparently be stolen by just about anyone with a radio frequency (RF) scanner. They can be found in just about everything these days including passports, ATM cards, credit cards and some of the newer state-issued driver's license. The same technology will likely even be used in paper currency in the near future.
To address this new level of identity theft "paranoia", manufacturers have started producing and selling products containing specially designed metal-infused fabrics that act as a miniature Faraday Cage by blocking electronic signals from passing through the material and potentially being scanned by data transponders. Just do a Google search for "RFID blocking wallets" and you'll see what I mean.
I'm no expert in RFID technology or passive data transmission by RF devices, but the whole topic does sort of intrigue me in a conspiracy theory kind of way. It also struck me that not only were most of these RF blocking products pretty darn expensive, they weren't exactly light weight (the EMFX-47 for example weighs close to 4oz). That got me to thinking about how I could make something myself to achieve the same RF shielding results but which would weigh considerably less than a store bought product.
The lightest weight material that I have is Cuben Fiber, which depending on the thickness can weight almost nothing at all. Many months ago I was very kindly sent a set of Cuben Fiber samples from Jon Holweger (some of which I made into ultralight stuff sacks), one piece of which was foil backed. It was one of the lighter weight pieces, but at the time I had no idea what I would do with it. Until I started thinking about RF shielding - eureka!
Using my sewing machine I created a simple pouch by folding the foil coated Cuben Fiber sample in half (foil side outwards) and stitching across the bottom and up the long side. I then turned it inside out so that the unsightly seam was on the inside. To make the flap of the pouch I cut a simple notch out of one side of the pouch - I wasn't too concerned with fraying because the Cuben Fiber is incredibly strong and fray resistant.
To make my RF shielding pouch stay closed when I put my phone or items inside it, I used two small 3M self-adhesive Velcro squares. In hindsight one set of Velcro would have been enough but I used to pairs to balance it out - these probably equate to the majority of the weight too.
My iPhone fits inside with plenty of room to spare. The overall RF shielding pouch measures 3.5 x 6 inches when closed which means it will accommodate not only my iPhone but a Passport, several credit cards and any other items that I want to make fall off the grid :-)
But did it work?
Heck yeah! In tests with several different cell phones I was not able to call or make any connection to the device once it was put inside the pouch. When I took a device out of the pouch it would search for a network and then be able to receive calls. Put it back inside the pouch and again it was out of signal reach.
I have no way to test the effectiveness of the passive RFID shielding, but have extremely high confidence that it will thwart any passive scanning attempts based on what I have seen with the cell phones.
My digital weighing scales go down as low as 1/8 of an oz (0.125oz) so my home-made ultralight 'Faraday Cage' pouch is <0.125oz including the two pairs of Velcro fasteners. That's pretty darn light weight :-)
Other good articles/reviews about RF shielding pouches:
- Loksak ShieldSak Review (by USNERDOC)
- Carry a Cloaking Device for your Cell Phone anywhere you go (by ITS Tactical)