US Patent 11238247 RFID tag and reader

A radio frequency identification (RFID) tag and reader system including an array of circular resonators with interdigitated capacitor fingers wherein the fingers of each pair are radially aligned and bars disposed between the resonators to reduce coupling between adjacent resonators, wherein subsets of the resonators resonate at respective different resonant frequencies, and the resonators of each of the subsets have the same resonant frequency; and the radio frequency response produced by the tag at a resonant frequency varies depending on the activation of resonators of the subset corresponding to the resonant frequency.