Quantitative Theory of Signal Inversion in RFID.

Inversion is a phenomenon that affects the signal received by an RFID reader from a transponder in an unwanted way, as it creates zones of non-communication on the reader antenna. In a previous work we have shown how to locate and evaluate inversion with the aid of 2D maps produced with an automated scanner. The present paper supplements that work with a theory that clarifies the dependence of inversion on the parameters of the transponder circuit and on the magnetic coupling between antenna and transponder.