Abstract: The present disclosure provides systems and methods associated with mode conversion for electromagnetic field modification. A mode converting structure (holographic metamaterial) is formed with a distribution of dielectric constants chosen to convert an electromagnetic radiation pattern from a first mode to a second mode to attain a target electromagnetic radiation pattern that is different from the input electromagnetic radiation pattern. A solution to a holographic equation provides a sufficiently accurate approximation of a distribution of dielectric constants that can be used to form a mode converting device for use with one or more transmission lines, such as waveguides. One or more optimization algorithms can be used to improve the efficiency of the mode conversion.

Abstract: Empirically modulated antenna systems and related methods are disclosed herein. An empirically modulated antenna system includes an antenna and a controller programmed to control the antenna. The antenna includes a plurality of discrete scattering elements arranged in a one- or two-dimensional arrangement. A method includes modulating operational states of at least a portion of a plurality of discrete scattering elements of the antenna in a plurality of different modulation patterns. The plurality of different modulation patterns includes different permutations of the discrete scattering elements operating in different operational states. The method also includes evaluating a performance parameter of the antenna responsive to the plurality of different empirical one- or two-dimensional modulation patterns. The method further includes operating the antenna in one of the plurality of different one- or two-dimensional empirical modulation patterns selected based, at least in part, on the performance parameter.

Abstract: The present disclosure provides system and methods for optimizing the tuning of impedance elements associate with sub-wavelength antenna elements to attain target radiation and/or field patterns. A scattering matrix (S-Matrix) of field amplitudes for each of a plurality of modeled lumped ports, N, may be determined that includes a plurality of lumped antenna ports, Na, with impedance values corresponding to the impedance values of associated impedance elements and at least one modeled external port, Ne, located external to the antenna system at a specified radius vector. Impedance values may be identified through an optimization process, and the impedance elements may be tuned (dynamically or statically) to attain a specific target radiation pattern.

Abstract: In one embodiment, an antenna system performance metric for a tunable antenna system comprising tunable impedance elements is identified. The tunable impedance elements are simulated as uniquely numbered lumped ports characterizing a port network with a corresponding admittance or impedance matrix. The admittance or impedance matrix can be approximated using the periodicity of the tunable antenna system and the S-matrix of the port network can be estimated using the approximated admittance or impedance matrix. An optimal configuration of the tunable antenna system with respect to the antenna system performance metric is identified from responses of the tunable antenna system to variable impedances using the S-matrix. The optimal configuration of the tunable antenna system includes impedances of the tunable impedance elements modeled as the lumped ports in the port network.

Abstract: A three-dimensional map of an environment with buildings is used to computationally predict locations and times of global navigation satellite system (GNSS) transmission quality. A global navigation satellite system (GNSS) receiver can reconcile received satellite transmissions with these predicted satellite transmissions. By comparing actual transmission quality with predicted transmission quality, a system can determine unmodeled obstructions, temporary obstructions, jamming, spoofing or other origins of interference with predicted transmission quality of a satellite in a GNSS.

Abstract: Holographic beamforming antennas may be utilized for adaptive routing within communications networks, such as wireless backhaul networks. Holographic beamforming antennas may be further utilized for discovering and/or addressing nodes in a communication network with steerable, high-directivity beams. Holographic beamforming antennas may be further utilized for extending the range of communications nodes and providing bandwidth assistance to adjacent nodes via dynamic adjacent cell assist. In some approaches, MIMO is used in concert with holographic beamforming for additional channel capacity.

Abstract: An airbag deployment system includes a helmet, a torso protection assembly, and an airbag assembly. The airbag assembly is coupled to one of the helmet and the torso protection assembly and includes an airbag, an inflation device configured to inflate the airbag, and a first coupling device. The first coupling device is configured to couple to a second coupling device provided on the other of the helmet and the torso protection assembly upon inflation of the airbag. The coupling resists relative movement between the helmet and the torso protection assembly.

Abstract: An antenna system includes a tunable medium, rectifier circuitry, combining circuitry, and control circuitry. The tunable medium includes antenna elements corresponding to lumped impedance elements and variable impedance control inputs configured to enable selection of an impedance value for each of the lumped impedance elements. The control circuitry is configured to determine a scattering matrix (S-matrix) relating field amplitudes at lumped ports including internal lumped ports and lumped external ports. The internal lumped ports correspond to the lumped impedance elements, and the lumped external ports correspond to at least one of the rectifier circuitry inputs, the combined output of the combining circuitry, and the at least one transmitting element. A method includes determining at least a portion of component values of a desired S-matrix, and adjusting the variable impedance control inputs to at least approximate at least a portion of the desired S-matrix.

Abstract: The present disclosure provides systems and methods associated with mode conversion for ultrasound and acoustic radiation devices. A mode converting structure (holographic metamaterial) is formed with a distribution of acoustic material properties selected to convert an acoustic pressure pattern from a first mode to a second mode to attain a target radiation pattern that is different from the input radiation pattern. A solution to a holographic equation provides a sufficiently accurate approximation of a distribution of acoustic material properties to form a mode converting device. One or more optimization algorithms can be used to improve the efficiency of the mode conversion and generation of the acoustic mode converter.

Abstract: An antenna system includes a tunable medium, rectifier circuitry, combining circuitry, and control circuitry. The tunable medium includes antenna elements corresponding to lumped impedance elements and variable impedance control inputs configured to enable selection of an impedance value for each of the lumped impedance elements. The control circuitry is configured to determine a scattering matrix (S-matrix) relating field amplitudes at lumped ports including internal lumped ports and lumped external ports. The internal lumped ports correspond to the lumped impedance elements, and the lumped external ports correspond to at least one of the rectifier circuitry inputs, the combined output of the combining circuitry, and the at least one transmitting element. A method includes determining at least a portion of component values of a desired S-matrix, and adjusting the variable impedance control inputs to at least approximate at least a portion of the desired S-matrix.

Abstract: A coded aperture sensing system includes a tunable coding aperture positioned relative to one or more electromagnetic (EM) detectors and voxels to scatter EM radiation traveling from the voxels towards the EM detectors. The system also includes a controller configured to determine EM fields at each of the voxels. A method includes determining a desired aggregate coding matrix of the tunable coding aperture, determining control parameters corresponding to the desired aggregate coding matrix, applying sequentially each of the control parameters to tunable inputs of the tunable coding aperture, and determining the EM fields at each of the voxels. Determining the EM fields includes determining the EM fields at least in part as a function of EM fields detected at the EM detectors responsive to each of the controls being applied to the tunable inputs of the tunable coding aperture.

Abstract: This disclosure provides systems and methods relating to medical devices that utilize dynamically tunable antennas comprising a plurality of sub-wavelength antenna elements. In various embodiments, impedance elements associated with the sub-wavelength antenna elements are dynamically tuned to control radiation patterns of a tunable antenna, such as a metamaterial surface antenna technology (MSA-T) antenna. The radiation patterns produced by the tunable antenna are used, for example, for sending a control signal to an implanted medical device, directly controlling the movement of a medical device, causing a medical device to perform a specific function, powering a medical device, and/or otherwise interacting a medical device. In some embodiments, the implanted medical device may also include an antenna, such as an MSA-T antenna, for receiving and/or sending beam-formed electromagnetic radiation.

Abstract: Described embodiments include a system and method. A system includes a tracking circuit configured to determine a location of a target device within a Fresnel region of an electronically reconfigurable beam-forming antenna. The antenna is configured to implement at least two selectable focused electromagnetic beams within its Fresnel region. The system includes a beam selector circuit configured to select from the at least two selectable focused electromagnetic beams a focused electromagnetic beam having a focal spot that covers at least a portion of the determined location of the target device. The system includes a beam definition circuit configured to determine an electromagnetic field distribution over an aperture of the electronically reconfigurable beam-forming antenna implementing the selected focused electromagnetic beam. The system includes an output circuit configured to transmit a signal indicative of the determined electromagnetic field distribution.

Abstract: Antenna systems and related methods are disclosed. An antenna system includes an antenna controller configured to operably couple to control inputs of an antenna including an array of electromagnetic (EM) scattering elements. A method includes controlling an array of EM scattering elements to operate according to holographic modulation patterns, and modulating at least one effective EM property of the antenna over space, time, or a combination thereof to, in the average and/or the aggregate, cause side lobes of an antenna gain of the antenna to be reduced.

Abstract: Described embodiments include a system and a method. A system includes an electromagnetic structure having a surface and a radiofrequency electromagnetic field source. The field source includes electronically controllable, artificially structured electromagnetic unit cells configured to create quasi-static electromagnetic fields within the electromagnetic structure. Each unit cell is responsive to a control signal. A selector circuit selects a quasi-static electromagnetic field pattern creating a high contrast electric field in a subwavelength electromagnetic cavity and is defined by the surface of the electromagnetic structure and an exterior surface of a perturbing object. The high contrast electric field has a power density that is localized to a volume adjoining the exterior surface of the perturbing object. A field pattern implementation circuit generates the control signal assigning electromagnetic field characteristic to each of the electromagnetic unit cells.

Abstract: Described embodiments include a system and method. An antenna is configured to implement at least two selectable radiative electromagnetic field spatial distributions. Each selectable radiative electromagnetic field spatial distributions respectively has a bounding surface that describes a specified power density in the radiative electromagnetic field. A sensor circuit is configured to detect a presence of an object within the bounding surface of an implemented radiative electromagnetic field. A countermeasure circuit is configured to select a response to the detected presence of the object within the bounding surface of the implemented radiative electromagnetic field.

Abstract: Diffractive concentrator structures can provide a large emittance angle and a large beamforming aperture for radiation emitted by a small transmit aperture and then delivered to a larger exit aperture.

Abstract: A three-dimensional map of an environment with buildings is used to computationally predict locations and times of global navigation satellite system (GNSS) transmission quality. A global navigation satellite system (GNSS) receiver can reconcile received satellite transmissions with these predicted satellite transmissions. By comparing actual transmission quality with predicted transmission quality, a system can determine unmodeled obstructions, temporary obstructions, jamming, spoofing or other origins of interference with predicted transmission quality of a satellite in a GNSS.

Abstract: The present disclosure provides system and methods for calibrating a tunable metamaterial device. A sequence of port impedance vectors, (z(m), m), may be generated. Each of the port impedance vectors may be applied to the tunable metamaterial device, and measuring at least one S-parameter. A simulated S-Matrix may be generated by associating each of the port impedance vectors, z(m), with the unknown admittance matrix. The unknown admittance matrix may be solved for by determining a plurality of optimization variables by comparing each of the S-parameters, S(m), to the simulated S-Matrix for each port impedance vector, z(m), and generating an estimated admittance matrix by associating each of the optimization variables with the unknown admittance parameters. The estimated admittance matrix may be used for more accurate radiation patterning.

Abstract: An audio surveillance system includes a plurality of nodes and each node includes a microphone, a speaker, and a control unit. The microphone is configured to detect sound and the speaker is configured to provide sound. The control unit is configured to receive a plurality of inputs from the plurality of nodes and the plurality of inputs are based on a detected sound; determine a location of the source of the detected sound based on the plurality of inputs; classify the detected sound according to predefined alert conditions and based on the location of the source of the detected sound; provide an alert to a monitoring device regarding the detected sound based on the classification of the detected sound; and control at least one node from the plurality of nodes to provide an audio response to the detected sound.