Abstract: A method for constructing a multifunctional antenna structure configured to generate a plurality of radiation patterns includes determining a desired source field associated with the plurality of radiation patterns, and receiving feed locations for a waveguide to an antenna aperture surface. The method may further include placing a metasurface resonator at a first resonator location that exhibits a minimum error relative to the desired source field and satisfies a maximum error threshold relative to the desired source field. The metasurface resonator may be determined based on the feed locations and a plurality of degrees of freedom for the first resonator location. The method may also include discarding a second resonator location in response to determining that no metasurface resonator at the second resonator location satisfies the maximum error threshold. The plurality of degrees of freedom may include metasurface resonator geometries that exhibit different polarizabilities defined in a candidate library.

Abstract: A metasurface device in the form of a unit cell may include a first metasurface sub-cell configured to exhibit a first resonant electromagnetic field (EMF) response and a second metasurface sub-cell configured to exhibit a second resonant EMF response. Each the two metasurface sub-cells may include a patterned layer and a variable impedance element operably coupled to the patterned layer. The variable impedance element may be configured to, in response to receipt of a control signal, change an impedance of the respective metasurface sub-cell based on the control signal to change the EMF response of the sub-cell. The first metasurface sub-cell and the second metasurface sub-cell may be disposed in a cascaded configuration such that first EMF response and the second EMF response couple to exhibit an integrated EMF response for the metasurface unit cell.

Abstract: According to various embodiments, systems and methods for spatial sampling in proximity to the Nyquist limit in traveling-wave antenna systems are disclosed. An apparatus can include a traveling-wave antenna array comprising a plurality of adjacent traveling-wave antennas that each include a plurality of tunable elements that are spaced at, near, or above a Nyquist limit spacing to form an array of tunable elements. The apparatus also includes a phase diversity feed coupled to the traveling-wave antenna array that is configured to provide input to the traveling-wave antenna array including phase diverse input to two or more of the plurality of adjacent traveling-wave antennas. Further, the apparatus includes a plurality of grayscale tuning elements configured to tune the plurality of tunable elements along one or more ranges of one or more tuning variables to form one or more specific output radiation patterns through the traveling-wave antenna array based on the input.

Abstract: A MIMO communication system is provided. The system may include a first antenna comprising a first cavity, a first plurality of RF ports for generating a feed wave within the first cavity, and a first plurality of sub-wavelength artificially structured material elements as arranged on a surface of the first cavity as RF radiators. The first antenna is configured to generate a plurality of radiation patterns respectively corresponding to the first plurality of ports. The system may also include a second antenna comprising a second cavity and a second plurality of sub-wavelength artificially structured material elements arranged on a surface of the second cavity.

Abstract: According to various embodiments, systems and methods for spatial sampling in proximity to the Nyquist limit in traveling-wave antenna systems are disclosed. An apparatus can include a traveling-wave antenna array comprising a plurality of adjacent traveling-wave antennas that each include a plurality of tunable elements that are spaced at, near, or above a Nyquist limit spacing to form an array of tunable elements. The apparatus also includes a phase diversity feed coupled to the traveling-wave antenna array that is configured to provide input to the traveling-wave antenna array including phase diverse input to two or more of the plurality of adjacent traveling-wave antennas. Further, the apparatus includes a plurality of grayscale tuning elements configured to tune the plurality of tunable elements along one or more ranges of one or more tuning variables to form one or more specific output radiation patterns through the traveling-wave antenna array based on the input.

Abstract: According to various embodiments, systems and methods for spatial sampling in proximity to the Nyquist limit in traveling-wave antenna systems are disclosed. An apparatus can include a traveling-wave antenna array comprising a plurality of adjacent traveling-wave antennas that each include a plurality of tunable elements that are spaced at, near, or above a Nyquist limit spacing to form an array of tunable elements. The apparatus also includes a phase diversity feed coupled to the traveling-wave antenna array that is configured to provide input to the traveling-wave antenna array including phase diverse input to two or more of the plurality of adjacent traveling-wave antennas. Further, the apparatus includes a plurality of grayscale tuning elements configured to tune the plurality of tunable elements along one or more ranges of one or more tuning variables to form one or more specific output radiation patterns through the traveling-wave antenna array based on the input.

Abstract: A MIMO communication system is provided. The system may include a first antenna comprising a first cavity, a first plurality of RF ports for generating a feed wave within the first cavity, and a first plurality of sub-wavelength artificially structured material elements as arranged on a surface of the first cavity as RF radiators. The first antenna is configured to generate a plurality of radiation patterns respectively corresponding to the first plurality of ports. The system may also include a second antenna comprising a second cavity and a second plurality of sub-wavelength artificially structured material elements arranged on a surface of the second cavity.

Abstract: A single frequency, or very narrow frequency band, microwave imaging system is described herein. A microwave imaging system can include an array transmitter; an array receiver; and a computing device that receives signals detected from the array receiver, transforms the signals received by the array receiver into independent spatial measurements, constructs an image using the independent spatial measurements, and outputs a reconstructed image. The array transmitter and the array receiver may each have a plurality of independently controllable metasurface resonant elements.

Abstract: A method for constructing a multifunctional antenna structure configured to generate a plurality of radiation patterns includes determining a desired source field associated with the plurality of radiation patterns, and receiving feed locations for a waveguide to an antenna aperture surface. The method may further include placing a metasurface resonator at a first resonator location that exhibits a minimum error relative to the desired source field and satisfies a maximum error threshold relative to the desired source field. The metasurface resonator may be determined based on the feed locations and a plurality of degrees of freedom for the first resonator location. The method may also include discarding a second resonator location in response to determining that no metasurface resonator at the second resonator location satisfies the maximum error threshold. The plurality of degrees of freedom may include metasurface resonator geometries that exhibit different polarizabilities defined in a candidate library.

Abstract: A MIMO communication system is provided. The system may include a first antenna comprising a first cavity, a first plurality of RF ports for generating a feed wave within the first cavity, and a first plurality of sub-wavelength artificially structured material elements as arranged on a surface of the first cavity as RF radiators. The first antenna is configured to generate a plurality of radiation patterns respectively corresponding to the first plurality of ports. The system may also include a second antenna comprising a second cavity and a second plurality of sub-wavelength artificially structured material elements arranged on a surface of the second cavity.

Abstract: An intracranial access device includes a housing having an operator-facing side and a patient-facing side and an opening therethrough extending from the operator-facing side to the patient-facing side. The device further includes at least one fastener configured to secure the device to a cranium of a patient. The device further includes a drill mounted to a surface of the housing and a cauterizer. The device may further include a number of sensors arranged on the patient-facing side of the housing and configured to identify a hemorrhage location.

Abstract: The present disclosure provides systems and methods relating to sensing the presence of a lifeform. In particular, the present disclosure provides systems and methods for detecting the presence of a lifeform in a building or room using dynamic metasurface aperture (DMA), which overcome many limitations of currently available radio frequency (RF) or infrared (IR)-based systems.

Abstract: A reconfigurable reflectarray antenna (RAA) system includes a reconfigurable RAA and a controller. The RAA includes a metasurface having a dynamically tunable electromagnetic characteristic and is configured to receive a signal of opportunity. The signal of opportunity is generated separately and independently from the reconfigurable RAA system. The controller is in signal communication with the reconfigurable RAA and is configured to generate a control signal configured to dynamically tune the electromagnetic characteristic of the metasurface. The electromagnetic characteristic includes a reflection phase, which when varied, dynamically beam steers the signal of opportunity reflected from the metasurface.

Abstract: A MIMO communication system is provided. The system may include a first antenna comprising a first cavity, a first plurality of RF ports for generating a feed wave within the first cavity, and a first plurality of sub-wavelength artificially structured material elements as arranged on a surface of the first cavity as RF radiators. The first antenna is configured to generate a plurality of radiation patterns respectively corresponding to the first plurality of ports. The system may also include a second antenna comprising a second cavity and a second plurality of sub-wavelength artificially structured material elements arranged on a surface of the second cavity.

Abstract: According to various embodiments, systems and methods for spatial sampling in proximity to the Nyquist limit in traveling-wave antenna systems are disclosed. An apparatus can include a traveling-wave antenna array comprising a plurality of adjacent traveling-wave antennas that each include a plurality of tunable elements that are spaced at, near, or above a Nyquist limit spacing to form an array of tunable elements. The apparatus also includes a phase diversity feed coupled to the traveling-wave antenna array that is configured to provide input to the traveling-wave antenna array including phase diverse input to two or more of the plurality of adjacent traveling-wave antennas. Further, the apparatus includes a plurality of grayscale tuning elements configured to tune the plurality of tunable elements along one or more ranges of one or more tuning variables to form one or more specific output radiation patterns through the traveling-wave antenna array based on the input.

Abstract: A MIMO communication system is provided. The system may include a first antenna comprising a first cavity, a first plurality of RF ports for generating a feed wave within the first cavity, and a first plurality of sub-wavelength artificially structured material elements as arranged on a surface of the first cavity as RF radiators. The first antenna is configured to generate a plurality of radiation patterns respectively corresponding to the first plurality of ports. The system may also include a second antenna comprising a second cavity and a second plurality of sub-wavelength artificially structured material elements arranged on a surface of the second cavity.

Abstract: A reconfigurable reflectarray antenna (RAA) system includes a reconfigurable RAA and a controller. The RAA includes a metasurface having a dynamically tunable electromagnetic characteristic and is configured to receive a signal of opportunity. The signal of opportunity is generated separately and independently from the reconfigurable RAA system. The controller is in signal communication with the reconfigurable RAA and is configured to generate a control signal configured to dynamically tune the electromagnetic characteristic of the metasurface. The electromagnetic characteristic includes a reflection phase, which when varied, dynamically beam steers the signal of opportunity reflected from the metasurface.

Abstract: The present disclosure provides systems and methods relating to sensing the presence of a lifeform. In particular, the present disclosure provides systems and methods for detecting the presence of a lifeform in a building or room using dynamic metasurface aperture (DMA), which overcome many limitations of currently available radio frequency (RF) or infrared (IR)-based systems.

Abstract: A single frequency, or very narrow frequency band, microwave imaging system is described herein. A microwave imaging system can include an array transmitter; an array receiver; and a computing device that receives signals detected from the array receiver, transforms the signals received by the array receiver into independent spatial measurements, constructs an image using the independent spatial measurements, and outputs a reconstructed image. The array transmitter and the array receiver may each have a plurality of independently controllable metasurface resonant elements.

Abstract: A single frequency, or very narrow frequency band, microwave imaging system is described herein. A microwave imaging system can include an array transmitter; an array receiver; and a computing device that receives signals detected from the array receiver, transforms the signals received by the array receiver into independent spatial measurements, constructs an image using the independent spatial measurements, and outputs a reconstructed image. The array transmitter and the array receiver may each have a plurality of independently controllable metasurface resonant elements.