Abstract: A method includes receiving, from a plurality of magnetic field receivers including magnetic sensors, data characterizing samples obtained by the plurality of magnetic field receivers, the samples of a combination of a first magnetic field and a second magnetic field resulting from interaction of the first magnetic field and an object; determining, using the received data, a polarizability index of the object, the polarizability index characterizing a magnetic polarizability property of the object; classifying, using the determined polarizability index, the object as threat or non-threat; and providing the classification. Related apparatus, systems, techniques, and articles are also described.

Abstract: A method includes receiving, from a plurality of magnetic field receivers including magnetic sensors, data characterizing samples obtained by the plurality of magnetic field receivers, the samples of a combination of a first magnetic field and a second magnetic field resulting from interaction of the first magnetic field and an object; determining, using the received data, a polarizability index of the object, the polarizability index characterizing a magnetic polarizability property of the object; classifying, using the determined polarizability index, the object as threat or non-threat; and providing the classification. Related apparatus, systems, techniques, and articles are also described.

Abstract: A method includes receiving data characterizing a signal obtained by a plurality of magnetic field receivers, the signal formed of a combination of a first magnetic field, a second magnetic field resulting from interaction of the first magnetic field and a first object, and a third signal resulting from motion of receivers within the first magnetic field and/or an external magnetic field other than the first magnetic field. The method also includes determining a component of the signal characterizing a contribution of the second magnetic field to the signal by multiplying the received data by a mapping that characterizes the contributions of the third signal to the signal to cancel the contributions of the third signal. The method further includes providing the determined component of the signal characterizing the contribution of the second field to the signal. Related systems and computer program products are also provided.

Abstract: A method includes receiving, from a plurality of magnetic field receivers including magnetic sensors, data characterizing samples obtained by the plurality of magnetic field receivers, the samples of a combination of a first magnetic field and a second magnetic field resulting from interaction of the first magnetic field and an object; determining, using the received data, a polarizability index of the object, the polarizability index characterizing a magnetic polarizability property of the object; classifying, using the determined polarizability index, the object as threat or non-threat; and providing the classification. Related apparatus, systems, techniques, and articles are also described.

Abstract: A method includes receiving, from a plurality of magnetic field receivers including magnetic sensors, data characterizing samples obtained by the plurality of magnetic field receivers, the samples of a combination of a first magnetic field and a second magnetic field resulting from interaction of the first magnetic field and an object; determining, using the received data, a polarizability index of the object, the polarizability index characterizing a magnetic polarizability property of the object; classifying, using the determined polarizability index, the object as threat or non-threat; and providing the classification. Related apparatus, systems, techniques, and articles are also described.

Abstract: A method includes receiving, from a plurality of magnetic field receivers including magnetic sensors, data characterizing samples obtained by the plurality of magnetic field receivers, the samples of a combination of a first magnetic field and a second magnetic field resulting from interaction of the first magnetic field and an object; determining, using the received data, a polarizability index of the object, the polarizability index characterizing a magnetic polarizability property of the object; classifying, using the determined polarizability index, the object as threat or non-threat; and providing the classification. Related apparatus, systems, techniques, and articles are also described.

Abstract: Data is received characterizing a plurality of measurements for a scene received by a plurality of sensor elements forming a sensor array. A plurality of scene sub-domains is mapped to the plurality of sensor elements. A plurality of voxels associated with one of the plurality of scene sub-domains is mapped to a plurality of measurement sub-domains. One or more scattering coefficients of the scene is determined by applying the mapping to the received data. Related apparatus, systems, techniques, and articles are also described.

Abstract: A method includes receiving, from a plurality of magnetic field receivers including magnetic sensors, data characterizing samples obtained by the plurality of magnetic field receivers, the samples of a combination of a first magnetic field and a second magnetic field resulting from interaction of the first magnetic field and an object; determining, using the received data, a polarizability index of the object, the polarizability index characterizing a magnetic polarizability property of the object; classifying, using the determined polarizability index, the object as threat or non-threat; and providing the classification. Related apparatus, systems, techniques, and articles are also described.

Abstract: A system includes a frequency modulated signal generator, a feed system, and an array of passive antenna elements. The frequency modulated signal generator can be producing a frequency modulated continuous wave signal. The feed system can be coupled to the frequency modulated signal generator for propagating the frequency modulated continuous wave signal. The array of passive antenna elements can be coupled to the feed system and can be configured to be excited by the frequency modulated continuous wave signal. The passive antenna elements can have resonant frequencies that are selected to generate a set of radiative field patterns corresponding to a set of known goal field patterns when the array of passive antenna elements are excited by the frequency modulated continuous wave signal. Related apparatus, systems, techniques, and articles are also described.

Abstract: A modular imaging system includes an antenna panels, a sensor, and at least one data processor. The antenna panels include an array of antenna elements including at least two antenna elements separated by a spacing more than a half wavelength. The plurality of antenna panels are configurable to be spatially arranged and oriented with respect to one another to measure radar returns of an observation domain for a target. The sensor has a field of view overlapping the observation domain and for measuring an image. The at least one data processor forms part of at least one computing system and is adapted to receive data characterizing the optical image and the radar returns, determine a spatial location of the target, and construct a radar return image of the target using a sparsity constraint determined from the spatial location of the target. Related apparatus, systems, techniques, and articles are also described.

Abstract: Data is received characterizing a plurality of measurements for a scene received by a plurality of sensor elements forming a sensor array. A plurality of scene sub-domains is mapped to the plurality of sensor elements. A plurality of voxels associated with one of the plurality of scene sub-domains is mapped to a plurality of measurement sub-domains. One or more scattering coefficients of the scene is determined by applying the mapping to the received data. Related apparatus, systems, techniques, and articles are also described.

Abstract: Data is received characterizing a measurement for a scene received by a plurality of sensor elements forming a sensor array. Intermediate scattering coefficients can be determined using the received data by applying to the received data a mapping of a plurality of scene sub-domains to the plurality of sensor elements. A parameter of an object within the scene can be estimated using the intermediate scattering coefficients. Related apparatus, systems, techniques, and articles are also described.

Abstract: Data is received characterizing a plurality of measurements for a scene received by a plurality of sensor elements forming a sensor array. A plurality of scene sub-domains is mapped to the plurality of sensor elements. A plurality of voxels associated with one of the plurality of scene sub-domains is mapped to a plurality of measurement sub-domains. One or more scattering coefficients of the scene is determined by applying the mapping to the received data. Related apparatus, systems, techniques, and articles are also described.

Abstract: A modular imaging system includes an antenna panels, a sensor, and at least one data processor. The antenna panels include an array of antenna elements including at least two antenna elements separated by a spacing more than a half wavelength. The plurality of antenna panels are configurable to be spatially arranged and oriented with respect to one another to measure radar returns of an observation domain for a target. The sensor has a field of view overlapping the observation domain and for measuring an image. The at least one data processor forms part of at least one computing system and is adapted to receive data characterizing the optical image and the radar returns, determine a spatial location of the target, and construct a radar return image of the target using a sparsity constraint determined from the spatial location of the target. Related apparatus, systems, techniques, and articles are also described.

Abstract: Data is received characterizing a plurality of measurements for a scene received by a plurality of sensor elements forming a sensor array. A plurality of scene sub-domains is mapped to the plurality of sensor elements. A plurality of voxels associated with one of the plurality of scene sub-domains is mapped to a plurality of measurement sub-domains. One or more scattering coefficients of the scene is determined by applying the mapping to the received data. Related apparatus, systems, techniques, and articles are also described.

Abstract: Data is received characterizing a measurement for a scene received by a plurality of sensor elements forming a sensor array. Intermediate scattering coefficients can be determined using the received data by applying to the received data a mapping of a plurality of scene sub-domains to the plurality of sensor elements. A parameter of an object within the scene can be estimated using the intermediate scattering coefficients. Related apparatus, systems, techniques, and articles are also described.

Abstract: A system includes a frequency modulated signal generator, a feed system, and an array of passive antenna elements. The frequency modulated signal generator can be producing a frequency modulated continuous wave signal. The feed system can be coupled to the frequency modulated signal generator for propagating the frequency modulated continuous wave signal. The array of passive antenna elements can be coupled to the feed system and can be configured to be excited by the frequency modulated continuous wave signal. The passive antenna elements can have resonant frequencies that are selected to generate a set of radiative field patterns corresponding to a set of known goal field patterns when the array of passive antenna elements are excited by the frequency modulated continuous wave signal. Related apparatus, systems, techniques, and articles are also described.