Patent ID: 7005964

Claim:
A SAW RFID tag or sensor, having: an antenna for receiving and propagating an RF signal; an input/output interdigital transducers (IDT) electrically connected to the antenna; and a dual track reflective IDT having a first track and a second track located adjacent and acoustically coupled to the input/output IDT, whereby said RF signal received from the antenna by the input/output IDT is transformed by the input/output IDT into an acoustic wave which is propagated to the dual track IDT; and one track of the dual track IDT being in-phase with the phase reference of the input/output IDT and the other track being in quadrature phase with said phase reference, whereby the input/output IDI receives two orthogonal complex modulated acoustic waves reflected from the first and second tracks and transforms them to a modulated orthogonal complex RF signal which is propagated from the antenna.