Abstract: A monopole antenna, comprising: a radiating element, wherein the radiating element has a first curved outer surface that is rotationally symmetric about a longitudinal axis extending through the monopole antenna, wherein a first diameter at a first end of the radiating element is less than a second diameter at a second end of the radiating element; and a ground plane disposed opposite the radiating element such that an electric field is generated by the radiating element with a ground plane providing the counterpoise, wherein the ground plane has a second curved outer surface that is rotationally symmetric about the longitudinal axis, wherein a first diameter at a first end of the ground plane is less than a second at a second end of the ground plane, wherein the first end of the radiating element is disposed adjacent the first end of the ground plane.

Abstract: A method for radar signal processing separates an electric signal generated by Doppler processors of a radar into alternating current (AC) magnitudes with Doppler frequencies corresponding to absolute values between 0.1 and 4 Hz and direct current (DC) magnitudes with no Doppler frequency. An AC line and a DC line are generated, based on the AC magnitudes and the DC magnitudes, respectively, by adding respective energies across Doppler cells for each range cell and subsequently applying CFAR detector algorithm respectively. An energy level difference between an energy spike in the AC line and another energy spike in the DC line is calculated and compared with a threshold set for detecting a breathing target that is stationary. If the energy level difference is greater than the threshold, the breathing target that is stationary is detected and reported to the radar operator.

Abstract: A method of processing a radar hit from an object using, for each of a plurality of cells, a signal strength threshold, a hit rate threshold, a time of last detection; and receiving, for one of the plurality of cells corresponding to the object, a measured signal strength, a measured hit rate and a time of measurement. The object is identified as clutter if the measured hit rate is greater than the hit rate threshold, and the measured signal strength is less than signal strength threshold. The signal strength threshold is above a conventional CFAR signal threshold. Measured Doppler strength may also be used to identify clutter. Identification can be determined using Doppler-polarity-specific data values. The hit rate and the mean Doppler speed of the one of the plurality of cells can be updated using a running average.

Abstract: A radar system, comprising: a receive antenna configured to receive a receive signal reflected from a bullet, the receive signal exhibiting a Doppler shift according to the motion of the bullet; and a detector implementing a set of matched filters each configured to determine a measure of correlation between the Doppler shift of the receive signal and one of a set of pre-stored Doppler shifts, wherein each of the pre-stored Doppler shifts respectively represents the Doppler shift of a bullet passing the antenna at a different speed or a distance of a point of closest approach.

Abstract: A system for developing machine learning for use in the radiofrequency domain that produces a robust set of training data for machine learning from a small set of labelled training data that is bootstrapped with unlabeled electromagnetic environment data. A raw signal set is prepared from the labeled data and separately processed for any electromagnetic environment and interference signals as well as for a primary signal by applying the real electromagnetic environment data and then summed to generate a second data set that is larger than the first data set. Feature extraction is used to produce a bootstrapped labelled data set that is larger than the original labelled data set and that can be used as training data for machine language classification.

Abstract: A monopole antenna, comprising: a radiating element, wherein the radiating element has a first curved outer surface that is rotationally symmetric about a longitudinal axis extending through the monopole antenna, wherein a first diameter at a first end of the radiating element is less than a second diameter at a second end of the radiating element; and a ground plane disposed opposite the radiating element such that an electric field is generated by the radiating element with a ground plane providing the counterpoise, wherein the ground plane has a second curved outer surface that is rotationally symmetric about the longitudinal axis, wherein a first diameter at a first end of the ground plane is less than a second at a second end of the ground plane, wherein the first end of the radiating element is disposed adjacent the first end of the ground plane.

Abstract: An airborne radar system and signal interpretation approach that detects slow moving ground targets using angle and Doppler of Keystone formatting process, and is referred to as Angle-Doppler Keystone Formatting (ADK). ADK collapses the clutter ridge to a constant Doppler or to a constant angle, thereby transforming a clutter ridge in angle-Doppler space into a horizontal line of constant Doppler or a vertical line of constant angle. Clutter may then be filtered more effectively, such as by using multiple beams as the source of STAP training data or by using multiple Doppler bins.

Abstract: An antenna array includes a first ground plane; a second ground plane disposed below the first ground plane; a folded monopole antenna disposed between the first ground plane and the second ground plane, the folded monopole antenna comprising a driven arm, a parasitic arm, and a short connecting the driven arm to the parasitic arm; an antenna disposed above the first ground plane; and a feedline in electrical communication with the antenna such that an electrical signal input to the feedline drives the antenna, wherein the feedline extends through a cavity formed within the parasitic arm of the folded monopole antenna.

Abstract: A method for calibrating a phased array including an antenna array comprising a plurality of antenna elements, comprising the steps: measuring with a probe a first antenna element pattern of a first antenna element of the plurality of antenna elements; performing a spherical near-field to far-field transformation of the first antenna element pattern; transforming the far-field first antenna element pattern to a plane-wave spectrum; back transforming the plane-wave far-field first antenna element pattern to a reference point within the near-field of the antenna array; normalizing the first antenna element pattern according to, at least, the value at the phase center of the plane-wave near-field first antenna element pattern; and calibrating the first antenna element based, at least in the part, on the normalized first antenna element pattern.

Abstract: A radar system includes an antenna array including a plurality of antenna elements; and a transmitter portion coupled to the antenna array, the transmitter portion being configured to sequentially transmit a first transmit beam and a second transmit beam from a single pulse, the first transmit beam and second transmit beam being formed using the same aperture of the antenna array, wherein a skew angle of the first transmit beam is distinct from a skew angle of the second beam. Such radar system alternatively transmitting through subarrays and receiving each via the entire array and combining the signals such that the transmit and receive parts of one of two 2-way beams point in the same direction and the transmit and receive parts of the second 2-way beam point in the same direction and these directions are within a standard beamwidth of each other.

Abstract: A radar system includes an antenna array including a plurality of antenna elements; and a transmitter portion coupled to the antenna array, the transmitter portion being configured to sequentially transmit a first transmit beam and a second transmit beam from a single pulse, the first transmit beam and second transmit beam being formed using the same aperture of the antenna array, wherein a skew angle of the first transmit beam is distinct from a skew angle of the second beam. Such radar system alternatively transmitting through subarrays and receiving each via the entire array and combining the signals such that the transmit and receive parts of one of two 2-way beams point in the same direction and the transmit and receive parts of the second 2-way beam point in the same direction and these directions are within a standard beamwidth of each other.

Abstract: A system and method for tuning a transistor-based circuit. The system includes a negative impedance converter circuit having a capacitor, a first transistor, and a second transistor. As a current travels through the capacitor, the first transistor and the second transistor each sample voltage at the capacitor and invert the voltage at an input of the negative impedance converter circuit. The negative impedance converter circuit also has a third transistor in series with the capacitor. The third transistor has a base voltage. Changing the base voltage of the third transistor changes the voltage sampled by the first transistor and the second transistor.

Abstract: Processing of MIMO radar data generated from overlapped MIMO arrays. The method of virtualizing (basebanding the MIMO phase centers) allows for processing without the need to omit content/information/energy from overlapped virtual elements.

Abstract: A radar system, comprising: a receive antenna configured to receive a receive signal reflected from a bullet, the receive signal exhibiting a Doppler shift according to the motion of the bullet; and a detector implementing a set of matched filters each configured to determine a measure of correlation between the Doppler shift of the receive signal and one of a set of pre-stored Doppler shifts, wherein each of the pre-stored Doppler shifts respectively represents the Doppler shift of a bullet passing the antenna at a different speed or a distance of a point of closest approach.

Abstract: An accessory for tethering a cap for a SMA/SMP bulkhead to a device assembly without having to introduce elements that could compromise the integrity of the device assembly. The accessory includes a first portion that engages the SMA/SMP bulkhead and securely interconnects thereto, and a second portion that includes an opening where a tether chain is physically interconnected thereto. The tether chain includes the cap for the SMA/SMP bulkhead secured to the second end thereof.

Abstract: A new way of beamforming in a phased array through use of a compression algorithm. The compression algorithm provides a beamforming technique that requires less memory, computes beams faster, and can be done without losing information as compared to prior art beamforming methods.

Abstract: A system for developing machine learning for use in the radiofrequency domain that produces a robust set of training data for machine learning from a small set of labelled training data that is bootstrapped with unlabeled electromagnetic environment data. A raw signal set is prepared from the labeled data and separately processed for any electromagnetic environment and interference signals as well as for a primary signal by applying the real electromagnetic environment data and then summed to generate a second data set that is larger than the first data set. Feature extraction is used to produce a bootstrapped labelled data set that is larger than the original labelled data set and that can be used as training data for machine language classification.

Abstract: A radar system located on an antenna array mounted on a moving carrier and including plurality of antenna elements; a transmitter portion coupled to the antenna and configured to transmit a plurality of transmit beams, each including a corresponding orthogonal transmit waveform of a plurality of orthogonal transmit waveforms, each of the plurality of transmit beams having a transmit phase center spatially located at a respective point along the antenna array, the transmitter portion being configured to transmit each transmit beam during at least a portion of a pulse repetition interval, wherein the transmitter portion is configured to shift the transmit phase center of each transmit beam for each pulse repetition interval to a respective point along the antenna array in a direction opposite the movement of the carrier, such that a speed of the respective transmit phase center of each beam remains is reduced.

Abstract: A spiral antenna, comprising a first arm and a second arm. The first arm and second arm are interlaced with each other. Each arm has a plurality of turns comprising an inner subset of circular turns, and an outer subset of turns, electrically coupled to the inner subset, having a shape with only four lines of symmetry. An array of such spiral antennas disposed a substrate that extends in a direction of a longitudinal axis and having a round cross section in a plan transverse to the longitudinal axis.

Abstract: Methods and systems for scalable high-performance embedded computing architectures. According to an embodiment, a scalable high-performance embedded computing system increases computational capability within the restrictive size, weight, and power constraints of systems such as the external pod payloads of unmanned aircraft systems, among many other possible systems. The core computer capability can be placed in various environments, and according to one embodiment utilizes a flight-certified aeronautics pod that is scalable in length. The scalable HPEC system can be connected to external data sources, or the nose and tail can be made of Radio Frequency transparent material, enabling the use of various RF sensing technologies within the same aeronautics enclosure. According to an embodiment, a lightweight, thermally-efficient conduction cooled chassis supports the required board and interface hardware.