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A comment on Ambient Backscatter: Wireless Communication Out of Thin Air [pdf]. Parent comment

Re:Ambient Backscatter: Wireless Communication Out of Thin A... by femto on Sunday July 07, 2013 @11:08PM (#6004925)
When I was at university, there was a final year undergraduate project that used similar technology. In this case, the student was trying to build a passive radar jammer, which modulated the reflected radar signal in a way that the driver of a car could select what speed they wanted to appear on a traffic radar.

The method was to build a corner reflector out of three orthogonal conducting sheets, but to connect one of the sheets to ground via a PIN diode switch. By turning the diode on and off, the reflection coefficient of the corner reflector could be modulated, in turn modulating the reflected signal.

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Re:Ambient Backscatter: Wireless Communication Out of Thin A... by jevinskie on Monday July 08, 2013 @12:17AM (#6005168)
Do you have a link? That is fascinating! Did it end up working?
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Re:Ambient Backscatter: Wireless Communication Out of Thin A... by femto on Monday July 08, 2013 @01:53AM (#6005360)
I don't have a link. It got written up as an undergraduate thesis in about 1991, but as far as I know the University of Sydney doesn't keep copies of such documents.

I'm not sure what the outcome was, though it must have gotten to a certain point of success, since I've memories of a car driving around with a corner reflector on it.

The same student was experimenting with using a plasma as the modulated reflector, but that one ended when he connected the wrong end of the vacuum pump to his gear, accidentally pressurised it, and blew it up!

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