Abstract: In an example embodiment, a system is provided to perform a convolution operation via optical fields. The system may include, for example, a Fourier transform lens to compute the Fourier transform of data encoded onto a coherent optical field. The system may also include a spatial light modulator to encode a superimposed object and constant function onto an optical field. The system may also include a spatial light modulator to encode a pattern onto an optical field. The system may also include a detector to detect the optical field that encodes the results of the convolution. In various instances, the detector is configured to detect the intensity of the optical fields encoding the result of convolutions. The first spatial light modulator may vary the phase between the signal and constant functions for each convolution that is encoded onto the field.

Abstract: In an embodiment, an antenna subsystem includes a sparse receive antenna and an electronically steerable transmit antenna. The sparse receive antenna includes an array of electronically steerable receive elements each configured to receive a respective signal having a wavelength and each spaced apart from each adjacent one of the receive elements by a respective first distance that is more than one half of the wavelength. And the electronically steerable transmit antenna includes an array of transmit elements each configured to radiate a respective signal having the wavelength and each spaced apart from each adjacent one of the transmit elements by a respective second distance that is less than one half of the wavelength. To reduce aliasing, such an antenna subsystem can be operated to filter, spatially, a receive beam pattern generated by the receive antenna with a transmit beam pattern generated by the transmit antenna.

Abstract: In an embodiment, an antenna unit includes a coupler, a phase-shifting modulator, and an antenna element. The coupler has first and second input-output ports, a coupled port, and an isolated port. The phase-shifting modulator includes a transmission medium coupled to the coupled port, a reflector, control nodes, and active devices each having a respective first device port coupled to a respective location of the transmission medium, a respective second device port coupled to the reflector, and a respective control port coupled to a respective one of the control nodes. And the antenna element is coupled to the phase-shifting modulator via the isolated port.

Abstract: According to various embodiments, an optoelectronic computer architecture is described herein for use as a convolutional neural network. The optoelectronic computer architecture includes a four-focal length (4F) optical subsystem that utilizes metasurfaces and lenses in conjunction with a digital electronic subsystem. Digital-to-analog converters and analog-to-digital converters are used to interface the optical subsystem and the digital subsystem. Various 4F lens and metasurface configurations are described herein, including various folded 4F lens configurations.

Abstract: This document is a disclosure of two related classes of metamaterial elements, based on a set of planar geometries that are homeomorphic to a coaxial element, or a sphere together with a torus. These cavities support a set of lossy optical resonances, known as quasinormal modes. Depending on the surrounding materials and the choice of quasinormal mode, the optical elements can be used either in transmission or reflection mode, and to generate either effective electric or magnetic dipoles. The metamaterial element is defined as a cavity with coaxial topology to operate in a particular range of quasinormal modes, defined by the mode numbers, within an operating bandwidth. The elements are tuned by application of a voltage differential to liquid crystal placed in the interior of the cavity of each respective element.

Abstract: An embodiment of a radar subsystem includes at least one antenna and a control circuit. The at least one antenna is configured to radiate at least one first transmit beam and to form at least one first receive beam. And the control circuit is configured to steer the at least one first transmit beam and the at least one first receive beam over a first field of regard during a first time period, and to steer the at least one first transmit beam and the at least one first receive beam over a second field of regard during a second time period.

Abstract: An embodiment an antenna unit of an antenna array includes a signal coupler, a phase-shifting modulator, and an antenna element. The signal coupler has a first input-output port, a second input-output port, and a coupled port. The phase-shifting modulator is coupled to the coupled port of the signal coupler, and the antenna element is coupled to the phase-shifting modulator via a connection remote from the signal coupler, or via an isolated port of the signal coupler. The phase-shifting modulator is configured for both relatively low signal loss and relatively low power consumption such that the antenna array can have significantly lower C-SWAP metrics than a conventional phased array while retaining the higher performance metrics of a conventional phased array.

Abstract: According to an embodiment, an antenna includes a conductive antenna element, a voltage-bias conductor, and a polarization-compensation conductor. The conductive antenna element is configured to radiate a first signal having a first polarization, and the voltage-bias conductor is coupled to a side of the antenna element and is configured to radiate a second signal having a second polarization that is different from the first polarization. And the polarization-compensating conductor is coupled to an opposite side of the antenna element and is configured to radiate third a signal having a third polarization that is approximately the same as the second polarization and that destructively interferes with the second signal. Such an antenna can be configured to reduce cross-polarization of the signals that its antenna elements radiate.

Abstract: An embodiment of a radar subsystem includes at least one antenna and a control circuit. The at least one antenna is configured to radiate at least one first transmit beam and to form at least one first receive beam. And the control circuit is configured to steer the at least one first transmit beam and the at least one first receive beam over a first field of regard during a first time period, and to steer the at least one first transmit beam and the at least one first receive beam over a second field of regard during a second time period.

Abstract: An embodiment of an antenna includes first and second transmission lines, first antenna elements, and second antenna elements. The first transmission line is configured to guide a first signal such that the first signal has a characteristic of a first value, and the second transmission line is configured to guide a second signal such that the second signal has the same characteristic but of a second value that is different than the first value. The first antenna elements are each disposed adjacent to the first transmission line and are each configured to radiate the first signal in response to a respective first control signal, and the second antenna elements are each disposed adjacent to the second transmission line and are each configured to radiate the second signal in response to a respective second control signal. Such an antenna can have better main-beam and side-lobe characteristics, and a better SIR, than prior antennas.

Abstract: An embodiment of an antenna array includes a transmit antenna and a receive antenna. The transmit antenna has, in one dimension, a first size, and has, in another dimension that is approximately orthogonal to the one dimension, a second size that is greater than the first size. And the receive antenna has, in approximately the one dimension, a third size that is greater than the first size, and has, in approximately the other dimension, a fourth size that is less than the second size. For example, such an antenna array, and a radar system that incorporates the antenna array, can provide a high Rayleigh resolution (i.e., a narrow Half Power Beam Width (HPBW)) with significantly reduced aliasing as compared to prior antenna arrays and radar systems for a given number of antenna-array channels.

Abstract: In an embodiment, an antenna unit for an antenna array allows shifting the phase of a radiated or received signal without the need for a phase shifter, and includes an antenna element, switching devices, and signal couplers. The antenna element includes at least one section and signal ports each electrically isolated from each other and from each of the at least one section. The switching devices are each configured to couple a respective one of the signal ports to one of the at least one section in response to a respective control signal, and the signal couplers are each configured to couple a respective one of the signal ports to a respective location of a respective transmission medium.

Abstract: In an embodiment, an antenna includes a one-dimensional array of antenna cells, a signal feed, and signal couplers. The antenna cells are each spaced from an adjacent antenna cell by less than one half a wavelength at which the antenna cells are configured to transmit and to receive, are configured to generate an array beam that is narrower in a dimension than in an orthogonal dimension, and are configured to steer the array beam in the dimension. And the signal couplers are each configured to couple a respective one of the antenna cells to the signal feed in response a respective control signal having an active level. For example, the antenna cells can be arranged such that a straight line intersects their geometric centers.

Abstract: Modulation patterns for surface scattering antennas provide desired antenna pattern attributes such as reduced side lobes and reduced grating lobes.

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: An embodiment an antenna unit of an antenna array includes a signal coupler, a phase-shifting modulator, and an antenna element. The signal coupler has a first input-output port, a second input-output port, and a coupled port. The phase-shifting modulator is coupled to the coupled port of the signal coupler, and the antenna element is coupled to the phase-shifting modulator via a connection remote from the signal coupler, or via an isolated port of the signal coupler. The phase-shifting modulator is configured for both relatively low signal loss and relatively low power consumption such that the antenna array can have significantly lower C-SWAP metrics than a conventional phased array while retaining the higher performance metrics of a conventional phased array.

Abstract: In an embodiment, an antenna unit for an antenna array allows shifting the phase of a radiated or received signal without the need for a phase shifter, and includes an antenna element, switching devices, and signal couplers. The antenna element includes at least one section and signal ports each electrically isolated from each other and from each of the at least one section. The switching devices are each configured to couple a respective one of the signal ports to one of the at least one section in response to a respective control signal, and the signal couplers are each configured to couple a respective one of the signal ports to a respective location of a respective transmission medium.

Abstract: In an embodiment, an antenna subsystem includes a sparse receive antenna and an electronically steerable transmit antenna. The sparse receive antenna includes an array of electronically steerable receive elements each configured to receive a respective signal having a wavelength and each spaced apart from each adjacent one of the receive elements by a respective first distance that is more than one half of the wavelength. And the electronically steerable transmit antenna includes an array of transmit elements each configured to radiate a respective signal having the wavelength and each spaced apart from each adjacent one of the transmit elements by a respective second distance that is less than one half of the wavelength. To reduce aliasing, such an antenna subsystem can be operated to filter, spatially, a receive beam pattern generated by the receive antenna with a transmit beam pattern generated by the transmit antenna.

Abstract: Surface scattering antennas with lumped elements provide adjustable radiation fields by adjustably coupling scattering elements along a wave-propagating structure. In some approaches, the surface scattering antenna is a multi-layer printed circuit board assembly, and the lumped elements are surface-mount components placed on an upper surface of the printed circuit board assembly. In some approaches, the scattering elements are adjusted by adjusting bias voltages for the lumped elements. In some approaches, the lumped elements include diodes or transistors.

Abstract: In an embodiment, an antenna subsystem includes a sparse receive antenna and an electronically steerable transmit antenna. The sparse receive antenna includes an array of receive elements each configured to receive a respective signal having a wavelength and each spaced apart from each adjacent one of the receive elements by a respective first distance that is more than one half of the wavelength. And the electronically steerable transmit antenna includes an array of transmit elements each configured to radiate a respective signal having the wavelength and each spaced apart from each adjacent one of the transmit elements by a respective second distance that is less than one half of the wavelength. To reduce aliasing, such an antenna subsystem can be operated to filter, spatially, a receive beam pattern generated by the receive antenna with a transmit beam pattern generated by the transmit antenna.