passive RFID tag design
I want to create a passive RFID tag which adds a specific time delay to the reflected signal. Doing some research it is clear I can print a cheap antenna and buy a S2 RFID IC, but I do not need to encode that much information on the reflected signal.
Anyone have any experience with RFID tag designs which rely on transmission lines and captive gaps to "encode" a reflected signal instead of an off the shelf IC?
Thanks in advance for your thoughts,
Sam
Doesn't sound to me like a feasible concept. Which RFID frequency band do you target at? Required transmission line length would be commanded by transmitter and receiver bandwidth respectively system time resolution. Can't imagine better resolution than 100 ns, or 13 m delay line per bit.
I dont plan on using an actual RFID band. As this is a pet project I was planning on using 5 GHz since I have access to decent sources, amps, antennas, microwave substrates, and test measurement equipment. I also want to keep the antennas and line lengths short, FCC be damned at the moment.
Calling this an RFID system may have been misleading. It is more of a pulsed radar system and I am looking for a passive method to differentiate the reflected pulse off the desired object rather than reflections off clutter. The goal was to embed a reflecting antenna which which would present a unique radar signature for the desired object. Perhaps an antenna which accepts linearly polarized energy and radiates the return pulse as circularly polarized?
I suppose I am looking to create a frequency selective surface which reflects an incident wave differently (measurably different) than a standard dielectric or metallic surface would.