X-ray Xbee

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By Becky Stern
Posted 2010/12/09 @ 7:42 am
Category Art & Design, Electronics

David Cranor put an Xbee radio in a CT scanner. Check out the closeup of the antenna!

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6 Responses to X-ray Xbee

theophrastus on December 9th, 2010 at 10:02 am said:

That’s really cool and unexpected (by me, at any rate). Immediately raises other questions.

Why only 3/4rds of a Hilbert curve (http://en.wikipedia.org/wiki/Hilbert_curve) for that square plane, (is somehow the effective length of 0.75 the quarter wavelength?)

So where’s the publication: “RF radiation from Regular Fractal Surfaces”?

…very interesting, thread, thank you.

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- Capn on December 9th, 2010 at 10:24 am said:
  
  HA! I was going to point out that that was a Hilbert Curve as well.
  
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Andrew Odewahn on December 10th, 2010 at 7:18 am said:

Cool — This king of fractal antenna (http://en.wikipedia.org/wiki/Fractal_antenna) has been around for a while. The inventor (not sure who) proved that almost any sort of self-similar curve that fills a plane will provide the best possible reception.

The patent doc for the original fractal antenna has some cool examples:

http://www.google.com/patents?id=bWALAAAAEBAJ&printsec=drawing&zoom=4#v=onepage&q&f=false

Also, the PBS series Nova did an episode about fractals that described how they were invented:

http://www.pbs.org/wgbh/nova/fractals/

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Andrew Odewahn on December 10th, 2010 at 7:22 am said:

ps — I meant to type “this *kind* of fractal antenna,” but I think I actually like “king” better…

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rdarlington.myopenid.com on December 10th, 2010 at 10:01 pm said:

In the future, consider using a styrofoam cup to support the PCB. They’re nearly transparent to x-rays. Also it looks like you need a little more filter material to cut down the softer x-rays, perhaps some .030″ copper sheet in front of the source as well as normalizing against a light and dark frame. Overall it’s not a bad scan but could be tweaked quite a bit. What was the tube set at?

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Jordan Husney on December 15th, 2010 at 2:32 pm said:

I’m an Engineer at Digi (makers of the XBee). We passed this link around the office today.

I thought I’d point out that this is the old ceramic chip antenna. We have a new fractal-based antenna on our XBee S2B (the new Series 2 design) and S2C (surface mount) radios with much improved performance over the chip antenna.

Our antenna design wizard tells me the old antenna gave -4.5 dB gain. The new one gives -1.8dB gain and has an extremely similar radiation pattern. It’s seriously rad! We’d love to see you take a new x-ray!

Jordan

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