Abstract: Methods for generating weights for the antenna elements (110) in an AESA antenna (100). In one embodiment, transmitting weights are selected to have unit amplitude and quadratic phase, and receiving weights are selected to provide a two-way antenna pattern which is uniform over a useful portion (300) of the main lobe, and decreases rapidly outside of the uniform portion. In another embodiment the transmitting weights have unit amplitude over a central portion of the array and the receiving weights are selected to provide a two-way antenna pattern which is uniform over a useful portion (300) of the main lobe.

Abstract: Embodiments are directed to generating a plurality of sub-images associated with a target via a synthetic aperture radar, processing, by a processor, the sub-images using a sub-aperture algorithm to generate an intermediate image, and applying, by the processor, a phase shift to the intermediate image to generate an output image.

Abstract: SAR imaging method that includes applying PRF decimation to range-compressed IQ data to generate PRF-decimated range-compressed IQ data for each image block of an image and applying motion compensation to the PRF-decimated range-compressed IQ data to generate motion-compensated data for each image block. The method includes computing first stage image values at image grid point intersections of iso-range lines and vertical grid lines for each image bock based on the motion-compensated data for each image block. The method also includes computing second stage image values for the image grid point intersections by interpolation using the first stage image values at the image grid point intersections and correcting image phase of the second stage image values for the image grid point intersections to generate phase-corrected image values for each image block. The method includes generating a full-resolution SAR image by summing the phase-corrected image values for each image block.

Abstract: Embodiments are directed to generating a plurality of sub-images associated with a target via a synthetic aperture radar, processing, by a processor, the sub-images using a sub-aperture algorithm to generate an intermediate image, and applying, by the processor, a phase shift to the intermediate image to generate an output image.

Abstract: A method of synthetic aperture radar autofocus for ground penetration radar. The method includes transmitting a signal via an antenna; receiving a reflected signal comprising a plurality of image blocks via the antenna; reading each image block from the reflected signal via a processor; locating prominent targets in each image block via the processor; estimating ground penetration phase error via the processor in each image block via phase error inputs including pulling range and quantization level by generating a 1D phase error and converting the 1D phase error into a 2D phase error of an image spectra; refocusing each image block according to estimated ground penetration phase error for that image block via the processor; and forming an image mosaic comprising each refocused image block via the processor.

Abstract: SAR imaging method that includes applying PRF decimation to range-compressed IQ data to generate PRF-decimated range-compressed IQ data for each image block of an image and applying motion compensation to the PRF-decimated range-compressed IQ data to generate motion-compensated data for each image block. The method includes computing first stage image values at image grid point intersections of iso-range lines and vertical grid lines for each image bock based on the motion-compensated data for each image block. The method also includes computing second stage image values for the image grid point intersections by interpolation using the first stage image values at the image grid point intersections and correcting image phase of the second stage image values for the image grid point intersections to generate phase-corrected image values for each image block. The method includes generating a full-resolution SAR image by summing the phase-corrected image values for each image block.

Abstract: A method of synthetic aperture radar autofocus for ground penetration radar (100). The method includes transmitting a signal via an antenna (102); receiving a reflected signal comprising a plurality of image blocks via the antenna (102); reading each image block from the reflected signal (602) via a processor (108); locating prominent targets in each image block (604) via the processor (108); estimating ground penetration phase error (606) via the processor (108) in each image block via phase error inputs (608) including pulling range and quantization level by generating a 1D phase error (706) and converting the 1D phase error into a 2D phase error of an image spectra (708); refocusing each image block according to estimated ground penetration phase error for that image block (610) via the processor (108); and forming an image mosaic comprising each refocused image block (614) via the processor (108).

Abstract: The technology described herein includes a system and/or a method of automated layout of beams. The method includes generating a plurality of boundary positions along boundaries of an image frame. The method further includes determining a start location for a first beam within the plurality of boundary positions based on at least one of a mapping priority, direction of movement of a beam platform, and speed of movement of the beam platform. The method further includes modifying the plurality of boundary positions based on the start location. The method further includes determining a second location for a second beam within the modified plurality of boundary positions based on at least one of a mapping priority, direction of movement of a beam platform, and speed of movement of the beam platform. The method further includes modifying the modified plurality of boundary positions based on the second location.

Abstract: The technology described herein includes a system and/or a method of automated layout of beams. The method includes generating a plurality of boundary positions along boundaries of an image frame. The method further includes determining a start location for a first beam within the plurality of boundary positions based on at least one of a mapping priority, direction of movement of a beam platform, and speed of movement of the beam platform. The method further includes modifying the plurality of boundary positions based on the start location. The method further includes determining a second location for a second beam within the modified plurality of boundary positions based on at least one of a mapping priority, direction of movement of a beam platform, and speed of movement of the beam platform. The method further includes modifying the modified plurality of boundary positions based on the second location.

Abstract: A method for processing squint-mapped synthetic aperture radar data of the present invention. The inventive method includes the steps of effecting range compression of the data; deskewing the data; performing a Fourier transform with respect to the deskewed data; providing a range migration interpolation of the transformed data; effecting a frequency remapping of the range interpolated data; and performing an inverse Fourier transform with respect to the deskewed data.

Abstract: Am image is reconstructed from x-ray attenuation data or other types of data using fast Fourier circular convolution (FFCC). Reference spectra and mask functions are generated for the FFCC. Also, the data is zero-padded for the FFCC. The data is transformed, multiplied by a radial filter, and transposed in order to construct the image by FFCC. The reconstructed image is converted from polar to Cartesian coordinates for viewing.

Abstract: A cryogenic rectification system for producing nitrogen having a low argon content wherein the reflux ratio in the upper portion of the higher pressure column of a double column system is modified by withdrawing nitrogen vapor from below the top of the column, liquefying the withdrawn vapor, and returning the liquefied nitrogen to the column at or near the withdrawal point and below the top of the column.