Patent ID: 8260204

Claim:
A device comprising: an antenna configured to receive a radio frequency (RF) signal and to generate an electrical signal from the RF signal; a substrate; a first interdigital transducer (IDT) configured to generate, from the electrical signal, a surface acoustic wave that propagates along the substrate; and a second IDT that is located on the substrate and has fingers that extend from two opposite terminals and are configured based on a code, the two opposite terminals being short circuited together so that the second IDT will receive the surface acoustic wave from the first IDT and reflect, back to the first IDT, a surface acoustic wave that includes a code based on a configuration of the fingers; the first IDT being configured to generate, from the reflected surface acoustic wave, an electrical signal based on the code; and the antenna being configured to transmit, from the coded electrical signal, a RF signal based on the code.