Abstract: The present invention is generally directed to systems, materials, and methods for ore tracking. In particular, the invention relates to metamaterial RFID tags that are chip-free and comprise RF metamaterials to produce unique spectral features when illuminated with microwave radiation. In one or more embodiments of the present invention, each of the metamaterial RFID tags includes one or more tag units that have a particular spectral response representing a one-bit code. As a result, each tag may comprise a specific code that is “assembled” from a plurality of tag units in a modular fashion. One or more embodiments of the present invention further includes a blast-tolerant package for one or more of the metamaterial RFID tags that enables such tags to survive blasting, crushing, and/or other forces inherent in mine operations.

Abstract: A new asynchronous localization method for a network of nodes and transmitters, the position of at least one of the nodes and/or transmitters being known, involves receiving a first signal directly from a first transmitter at a first node of a first node pair, receiving the first signal relayed from a second node of the first node pair at the first node, and determining the delay at the first node between the direct and relayed first signal by comparing the direct and relayed first signals. This may be repeated with the first node acting as relay to determine the delay at the second node. Time difference of arrival and/or time of flight between first and second nodes may be determined using the determined delay at the first and/or second node and/or known node locations. The process is repeated for additional transmitters/node pairs until sufficient information is determined for desired applications.

Abstract: A self-steering retrodirective array capable of both full-duplex communication and maintaining a constant retrodirected power level uses an angle-detecting array with a phase detector to detect the angle of the incoming signal from a source and generate an error voltage signal, and a transmitting array having a phase shifter controlled by the error voltage signal to retrodirect a beam back in the direction of the source. A phase shifter in the receiving array also ensures coherent combination of the incoming signal. The angle-detection array and transmitter array are RF-decoupled for full-duplex communication. The efficiency of the system is increased by using an interrogator signal at a much lower frequency than the transmitted signal. In a preferred embodiment, a simple two-element angle detecting array detects the direction of the source.

Abstract: A high-directivity transponder system uses a dual system of a retrodirective array transmitting a data signal peak toward an interrogator source, and a self-null-steering array transmitting a null toward the interrogator source and a jamming signal elsewhere, resulting in high S/N reception at the interrogator source and avoidance of interception. Integrating modulators would allow each array to transmit different data while the spectra of the transmitted signals are identical, thus disabling interception. The system enables secure point-to-point communications and can be used for short-distance wireless data transmission systems such as wireless LAN and RFID servers. As another aspect, self-steering signal transmission is employed for randomly oriented satellites using circularly polarized, two-dimensional retrodirective arrays. Quadruple subharmonic mixing is used as an effective means of achieving phase conjugation when a high-frequency LO is not feasible or inapplicable.

Abstract: A high-directivity transponder system uses a dual system of a retrodirective array transmitting a data signal peak toward an interrogator source, and a self-null-steering array transmitting a null toward the interrogator source and a jamming signal elsewhere, resulting in high S/N reception at the interrogator source and avoidance of interception. Integrating modulators would allow each array to transmit different data while the spectra of the transmitted signals are identical, thus disabling interception. The system enables secure point-to-point communications and can be used for short-distance wireless data transmission systems such as wireless LAN and RFID servers. As another aspect, self-steering signal transmission is employed for randomly oriented satellites using circularly polarized, two-dimensional retrodirective arrays. Quadruple subharmonic mixing is used as an effective means of achieving phase conjugation when a high-frequency LO is not feasible or inapplicable.