Raytheon Company

Raytheon Corporation

Thomas G Lavedas

Benjamin P Dolgin

Joseph J Fraundorfer

Gerald L Ehlers

Firat Kara

David G Penn

Milan Chukel

A system/device, such as a gradiometer probe for detecting RF signals, or for example for explosive detection, has the shape of the coils in its adjustment mechanism that minimizes the cross-talk between the receiver probe (Rx) and the transmitting antenna (Tx) in such a way as to minimize (or reduce) the areas where the distance between the coils during the adjustment is the smallest. Moving coils along the plain of the coils is one mechanism of achieving it. Having the coils of different shapes, e.g., circular receiver and oval transmitter coils, is another. Many shapes are possible, including circular, oval, elliptical, and polygonal, to give a few examples. In some embodiments both of these methods/approaches are combined in a single device.

Cross-talk compensation for gradiometer probes

A sensor probe with reduced coupling between the various antenna elements and suppression of radio frequency interference. In one embodiment the sensor probe comprises a first antenna and a second antenna. A first and a second decoupling loop is electrically connected to one of the first and second antennas with current flow in opposite directions in the first and second decoupling loops. A third decoupling loop is electrically connected to another one of the first and second antennas and physically disposed between the first and second decoupling loops. Coupling between the first and second antennas is responsive to a location of the third decoupling loop relative to the first and second decoupling loops.

Adjustment of near-field gradient probe for the suppression of radio frequency interference and intra-probe coupling

An apparatus includes an antenna, a transmitter configured to generate an outgoing electrical signal, and a receiver configured to receive an incoming electrical signal. The apparatus also includes a transformer configured to couple the antenna and the transmitter such that the outgoing electrical signal causes the antenna to radiate outgoing electromagnetic energy, couple the antenna and the receiver such that the incoming electrical signal is based on incoming electromagnetic energy received by the antenna, and electrically isolate the transmitter and the receiver. The antenna may include inner and outer compensating coils, the compensating coils may be configured to additively radiate the outgoing electromagnetic energy, and the incoming electrical signal may be based on a difference between the incoming electromagnetic energy as received by the compensating coils.

Differential probe with single transceiver antenna

An apparatus includes a near-field probe having loops or coils of electrically-conductive material, where the near-field probe is configured to generate a magnetic field. The apparatus also includes a power amplifier configured to drive the near-field probe. The apparatus further includes a shunt capacitance coupled in parallel across the loops or coils of the near-field probe. The shunt capacitance and an inductance of the loops or coils of the near-field probe form part of a resistive-inductive-capacitive (RLC) network. The RLC network is configured to transform a smaller resistance of the near-field probe into a larger resistance. In some cases, the apparatus may include multiple near-field probes coupled in series, and the power amplifier may be configured to drive the multiple near-field probes. For each near-field probe, the apparatus may include a shunt capacitance coupled in parallel across the loops or coils of the near-field probe.

Tuning of narrowband near-field probes

A system includes a table and a material detection system. The material detection system includes a transmit chain configured to generate first radio frequency (RF) signals and a transmit probe configured to transmit the first RF signals towards an item through open space. The material detection system also includes a receive probe configured to receive second RF signals from the item through open space, where the second RF signals have one or more characteristics indicative of one or more materials within the item. The material detection system further includes a receive chain configured to process the second RF signals and at least one processing device configured to identify the one or more materials within the item using nuclear quadrupole resonance (NQR) spectrometry based on the processed second RF signals. The transmit and receive probes are positioned in an upper portion of the table.

Material detection system

In some embodiments, a near-field sensor comprises an antenna system, transmit circuitry configured to transmit pulses via the antenna system, and receive circuitry configured to receive interrogation signals in response to transmitted pulses. The antenna system can include a first conductive path having one or more loops coupled together, and a second conductive path having one or more loops coupled together, wherein the first and second conductive path are electrically isolated from each other within the antenna system. The transmit circuitry can include a matching network to dissipate energy stored in the transmit circuitry following transmission of a pulse. The receive circuitry can include a suppression network configured to dissipate residual energy within the receive circuitry resulting from transmission of the pulse.

Diplexed near-field sensor

Antenna structures including two anti-symmetrically wound transformers to compensate for stray radiation. In one example an antenna structure includes a transformer assembly connected between an antenna and first and second balanced signal contacts, the transformer assembly including first and second transformer cores independently positionable in space relative to one another, a pair of primary windings connected to the antenna in parallel with one another, and a pair of balanced secondary windings connected in parallel with one another between the first and second balanced signal contacts.

Precision transformer for antenna elements

A system and method for detecting a nucleus of interest in a chemical using a nuclear quadrupole resonance transition. An excitation pulse is used to excite one or more nuclei of interest, if they present in a sample, to an excited state, the energy of which depends on the magnetic field in the sample. The magnetic field in the sample is modulated, after the end of the excitation pulse, while the nuclei of interest decay from the excited state, so that the radiation they emit is frequency modulated. The frequency modulation is detected in the emitted radiation. In some embodiments a DC magnetic field is applied to the sample, during the application of the excitation pulse, to tune the frequency of the transition being excited.

System and method for detection of chemicals using frequency modulated nuclear quadrupole resonance signals

Examples of passive diode-based transmitter detuning circuits and low-voltage active diode-based and receiver detuning circuits are provided.

Diode-based transmitter and receiver detuning circuits

An antenna system is provided comprising first, second, and third loop antennas, each antenna having a respective loop area and spaced apart from the other antennas. The first and third antennas are configured and driven to form a first independent balanced feed point that is substantially isolated from the second antenna, which is configured to be driven from a second balanced feed point. A sum of the first and second respective loop areas, at a sum port in operable communication with the first and second balanced feed points, is substantially equivalent to the third respective loop area. An automatic control system is configured to automatically and independently adjust, via the balanced feed points, at least one of amplitude and phase for at least one of the three loop antennas, to help to substantially maximize suppression of RFI for a sum of signals from the first and second balanced feed points.

Near-field gradient probe for the suppression of radio interference

An antenna system comprising a plurality of loop antenna sets with each of the plurality of loop antenna sets disposed in one of a plurality of different parallel planes with each of the planes being spaced apart from another adjacent plane and wherein loop antenna set in the plurality of loop antenna sets comprises a plurality of loop antennas and wherein the plurality of loop antennas are configured such that the near field inductive coupling between the plurality of loop antenna sets is zero. The absence of inductive coupling between the loop elements provides a frequency-independent means for multiplexing signals for transmission and reception by the multiple loop antenna system.

Diplexing and triplexing of loop antennas

A system for protecting radio frequency (RF) communications and related techniques includes generating masking signals at an RF device such as a radio frequency identification (RFID) card.

Protection system for radio frequency communications

An antenna for protecting radio frequency communications includes a masking portion to broadcast a masking signal including a first loop and a second loop connected to the first loop, wherein a current supplied to the masking portion flows in opposite polarity in each of the first and second loops. The antenna includes a reader loop to receive a response signal from a responder and decoupled from the masking signal, wherein the masking signal masks the response signal about the responder.

Antenna for protecting radio frequency communications

An antenna includes a first loop defining a first enclosed area and having a first phase center point, a second loop coupled to the first loop and disposed substantially parallel to the first loop, the second loop defining a second enclosed area, and a third loop coupled to the first loop and the second loop and substantially parallel to the first loop, the third loop defining a third enclosed area with a plurality of adjuster elements coupled to at least one of the first loop, the second loop, or the third loop to provide an adjustable loop and configured to expand or contract the enclosed area of the adjustable loop.

Method for controlling far field radiation from an antenna

A radio-frequency identification (RFID) inlay is provided that is substantially isolated from the environment in proximity to one side of the device. A radio-frequency identification (RFID) inlay is provided including a two-port microchip having a first and a second port, a first antenna coupled to the first port of the two-port microchip, a ground-plane, a first high-impedance body disposed substantially parallel to the first antenna and between the first antenna and the ground-plane, the first high-impedance body insulated from the ground-plane. The RFID inlay further includes a second antenna coupled to the second port of the two-port microchip, and a second high-impedance body disposed substantially parallel to the second antenna and between the second antenna and the ground-plane, the second high-impedance body insulated from the ground-plane.

Growing community of inventors

Clifton, VA, United States of America

Thomas G Lavedas