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.
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!
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.