High-tech home ec: Building a Faraday cage at the Interop Labs

As part of the VoIP demo at year’s Interop Labs, we’re building a Faraday cage. Last year, I did some basic research into quality of service using WMM by recording voice samples over the air, using the wireless traffic at the show floor for background noise.

This year, the team wanted to do something a bit more controlled. We had questions about how well WMM worked when more than a single call was prioritized. To control for the many variables of wireless traffic on the trade show floor, we needed to isolate the VoIP testing from everything else. During the staging event, Jed Daniels built a prototype Faraday cage to keep the show floor out, and our background traffic in.

Building a walk-in cage is a lot harder than building a small prototype. Faraday cages work best when they are a single conductive surface, but the walk-in cage was big enough that we had to join sheets of mesh. To improve conductivity between panels, we wound up “sewing” sheets together with copper wire.

Needles are not well designed for pulling wire through a small-aperture mesh, so we needed to sew in two-person teams. Here’s me working with Jed, pulling copper wire through the mesh as we sew along the base:
Sewing the cage, outside view

Here’s the reverse view, looking over Jed’s head towards the outside.
Sewing the cage, inside view

Here’s a shot of the final result, with Jed and an engineer from Veriwave working on the test tool to generate controlled background traffic for our demonstrations:
Jed in the cage

Finally, after all that work, we felt the need to “make our mark,” so all the people who worked on the cage sewed initials in to the front panel:
Initials in the cage
(From the upper left to the lower right, the initials are Jed Daniels, Mike McCauley, Matthew Gast, J.J. McNamara, Jerry Perser, Bill “WEJ” Jensen, and John Balogh.)

4 Responses to “High-tech home ec: Building a Faraday cage at the Interop Labs”

  1. […] However, As Matthew Gast illustrates, building a walk-in Faraday Cage is much harder than a small prototype. faraday cage, iLabs, Interop, jed daniels, las vegas, mandalay bay, matthew gast […]

  2. […] With Interop over, it’s worth jotting down a few lessons about the Interop Labs Faraday cage. First, the results were better than I expected, given the difficulty of building a complete RF shield. Based on measurements we took using both test tools and laptop-based tools, it appears that our cage provided about 40-45 dB of shield, which is a good amount given our abbreviated time and limited materials budget. For comparison, the VeriWave test chambers are guaranteed to provide at least 80 dB of shielding (though the number appears to be much higher in practice). […]

  3. Michael Coci says:

    MSG: you wrote: “We had questions about how well WMM worked when more than a single call was prioritized. ”

    I’m curious what the results were?

  4. Kevin Parkin says:

    Congrats on the Faraday cage 🙂 Just stumbled upon your site and it gave me fond memories of when I sewed my Faraday cage together. I used exact same aproach as you…

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