Radio frequency tag system

Abstract

The RF tag system of the present invention minimizes the effect of the RF tag on the overall radar cross section (RCS) of the object with which it is associated, tailors the signal reflected from the tag to match the actual RCS of the object with which it is associated, utilizes an RF tag design that reduces degenerative RF coupling at the tag, and is designed to exploit the operational features of conventional pulse Doppler radars. In accordance with one embodiment of the present invention, a radio frequency tag system is provided including an interrogator and a tag. The tag is secured to an object. The interrogator is configured to generate a transmitted electromagnetic interrogation signal at a predetermined interrogation frequency. The tag comprises an antenna array including a plurality of receiver antennas and a plurality of transmitter antennas. The tag is positioned to receive the interrogation signal at the receiver antennas and is operative to return a reflected signal to the interrogator via the transmitter antennas in response to receipt of the interrogation signal. The tag is configured to generate the reflected signal by (i) suppressing reflection of the interrogation signal, and (ii) generating reflected radiation characterized by a frequency spectrum including a plurality of return bands, each of the return bands being characterized by a predetermined return band frequency. The interrogator is configured to detect radiation reflected at the return band frequencies, discriminate between return bands of different frequencies, and identify a binary code defined by the reflected radiation across the plurality of return bands.