Spectra Research, Inc.

Ronald George Riechers

John William Sellers, Jr

Eugene E Mayle, Jr

Gary A Thiele

Paul Donald Zidek

Krishna Murthy Pasala

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.

Radio frequency tag system

A system for and method of electromagnetically detecting an embedded dielectric region within a target object are provided. The method includes the steps of: (i) selecting a target object including a plurality of discrete scattering mediums, wherein the plurality of discrete scattering mediums include the embedded dielectric region and an adjacent dielectric region, and wherein the plurality of discrete scattering mediums define at least one dielectric interface between the embedded dielectric region and the adjacent dielectric region; (ii) directing electromagnetic radiation at the target object, wherein the electromagnetic radiation is characterized by a diagnostic frequency that is varied incrementally over a diagnostic frequency band; (iii) detecting electromagnetic radiation reflected by the target object over the predetermined frequency band such that there are M measurements of a reflected electromagnetic signal at frequencies f.sub.1, f.sub.2, . . . , f.sub.N, where M represents a number of scattering mediums within the target object and where N represents a number of diagnostic frequencies within the diagnostic frequency band; (iv) constructing a correlation matrix representative of the reflected signal, wherein the correlation matrix comprises a number of signal eigenvectors and a number of noise eigenvectors; (v) decorrelating the correlation matrix by dividing the reflected signal according to frequency sub-bands within the diagnostic frequency band, wherein adjacent bands of the frequency sub-bands overlap, forming a series of iterated correlation matrices using signal eigenvectors and noise eigenvectors from each of the overlapping frequency sub-bands, forming a decorrelated matrix by averaging the iterated correlation matrices, wherein the decorrelated matrix comprises a finite group of signal eigenvectors and a finite group of noise eigenvectors; and (vi) constructing a scattering signature of the target object from the finite group of signal eigenvectors, wherein the scattering signature is indicative of the properties of the embedded dielectric region and the adjacent dielectric region.

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Beavercreek, OH, United States of America

Ronald George Riechers