Faraday Cage Phone Pouch

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Introduction: Faraday Cage Phone Pouch

About: Dabbled in dark matter, settled into engineering with a blend of inventing and teaching, always trying to solve problems + learn new things!

This Faraday Cage phone pouch blocks all radio signals coming in or out of your cellphone. Material costs are about $10, it takes ~ 30 minutes to build, and it can fit in your pocket!

The purpose of this pouch is to prevent access to your phone and its data (e.g. location) if and when you so choose. Before placing your phone in the pouch, be sure to put it in airplane mode as the phone will drain its battery trying to find a signal.

Check out this video if you want to learn more about Faraday Cages!

Step 1: Materials

-- Conductive fabric

Sized to fit your phone + a top flap. For an iPhone w/ a (giant) case, I needed about 7.5" x 3.5".

-- Thread (regular, any color)

-- Button (any type)

Alternatively, you can use velcro, a safety pin, or any other means to hold down the top flap.

Step 2: Tools

-- Scissors

-- Ruler

-- Needle or Sewing Machine (preferred)

-- Safety pins (optional but helpful)

Step 3: Build It! Pt. 1

1. Measure the width, height, and depth of your phone (+ case, if you have one).

2. Add 1" to your phone width measurement and 2" to your phone height measurement. Cut conductive fabric into a rectangle of that size.

For example, the iPhone 5 is 4.87" tall, 2.31" wide and 0.30" thick. Thus, you want a rectangle that is at least 6.5" tall and 3.5" wide.

To double check your measurements, mark where you plan to cut the conductive fabric w/ a pen or pencil. then wrap the fabric around your phone. Be sure that you can fold down the top of the conductive fabric.

Helpful tip: It's always better to leave extra room. Measure twice, cut once, and so forth.

3. Place phone on one side of the conductive fabric and fold the fabric over the phone. Safety pin sides together.
Leave an inch or two above the phone so the top can be folded over like an envelope.

Step 4: Build It! Pt. 2

1. Sew bottom + sides of conductive fabric together using small hand stitches or a sewing machine.

2. Turn pouch inside-out to hide stitching.

3. Place phone inside pouch, fold top down and mark where the button will go.

4. Sew button on & cut a small slit in the top flap to attach.

Remove excess fabric as necessary, but be sure that the conductive fabric completely encases the phone when the top flap is folded down.

Step 5: Done!

Place phone inside the Faraday Cage pouch whenever you want to cut off all radio signals coming in and out of your phone.

For another awesome version of the same concept, check out my friend's scarf project here.

Curious as to how this works? Awesome! In super simple terms, a Faraday Cage "traps" radio waves in the wires that make up the cage. In this design, the conductive fabric threads are the metal wires that form the Faraday Cage. Due to the small mesh size (aka wires are super close together), this design will block any electromagnetic radiation with a wavelength larger than visible light. :)

Here's a good overview on what a Faraday Cage is and how you can build a different version.

And here's the Wikipedia blurb on Faraday Cages, an excellent source if you want to learn more!

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    26 Comments

    Hi. I got a jacket made from conductive textile for working in a factory with small elektronic components. wheb i wrap my phone inside the jacket i can still make calls. Nothing get cancelled out. Is the textile not dense enough?

    1 reply

    Interesting question! Any air gaps in the fabric will allow radio signals to pass through. Try folding the phone into the jacket and smoothing out any wrinkles. If it still receives calls, then it likely has to do w/ mesh size.

    Thank you!

    Re: scaling up: Yes, absolutely! In fact, I used to work in a building that was an (accidental) Faraday Cage, and it effectively blocked all incoming radio waves. As long as you maintain sufficiently small mesh size (gaps b/w the wires) and have a full enclosure, you can make it as large or as little as you'd like.

    Great! Thanks for the information and the project! Keep up the good work!

    Happy to help :) & thank you v. much!

    Yup, many times. Calls/texts/e-mails/etc. do not go through while the phone is in the pouch and the top is closed. You'll receive texts/voicemails/emails when you take the phone out, although you will not receive a "missed call" notification.

    I didn't know my phone keeps searching for a signal if it does not have one.

    Wouldn't a metal box do the same thing?

    1 reply

    Yes, a metal box will do the exact same thing (as long as it has a lid), but that's less likely to fit in your pocket! :)

    I always enjoy your presentations . Very well thought out .

    1 reply

    super neat! nicely documented and great informational links for the less informed amongst us

    1 reply

    Thank you! Glad you found it helpful :D

    I love conductive fabric! I'd suggest placing the phone into airplane mode before sliding it in. If not, your battery will suffer while continually trying to find a connection with a tower. Great Project!

    1 reply

    Thanks! Yea, I made that disclaimer on the intro page.