Mobile devices, climate science, and autonomous vehicles all require advanced microwave antennas for imaging, radar, and wireless communications. We propose a waveguide-fed metasurface antenna architecture that enables electronic beamsteering from a lightweight circuit board with varactor-tuned elements. Our approach uses a unique feed structure and layout that enables spatial sampling at the Nyquist limit of half a wavelength.
View Article and Find Full Text PDFMetasurface antennas offer an alternative architecture to electrically large beamsteering arrays often used in radar and communications. The advantages offered by metasurfaces are enabled by the use of passive, tunable radiating elements. While these metamaterial elements do not exhibit the full range of phase tuning as can be obtained with phase shifters, they can be engineered to provide a similar level of performance with much lower power requirements and circuit complexity.
View Article and Find Full Text PDFThrough aperture synthesis, an electrically small antenna can be used to form a high-resolution imaging system capable of reconstructing three-dimensional (3D) scenes. However, the large spectral bandwidth typically required in synthetic aperture radar systems to resolve objects in range often requires costly and complex RF components. We present here an alternative approach based on a hybrid imaging system that combines a dynamically reconfigurable aperture with synthetic aperture techniques, demonstrating the capability to resolve objects in three dimensions (3D), with measurements taken at a single frequency.
View Article and Find Full Text PDFWe propose a polarimetric microwave imaging technique that exploits recent advances in computational imaging. We utilize a frequency-diverse cavity-backed metasurface, allowing us to demonstrate high-resolution polarimetric imaging using a single transceiver and frequency sweep over the operational microwave bandwidth. The frequency-diverse metasurface imager greatly simplifies the system architecture compared with active arrays and other conventional microwave imaging approaches.
View Article and Find Full Text PDFJ Opt Soc Am A Opt Image Sci Vis
May 2017
We investigate the application of dynamic metasurface antennas (DMAs) to synthetic aperture radar (SAR) systems. Metasurface antennas can generate a multitude of tailored electromagnetic waveforms from a physical platform that is low-cost, lightweight, and planar; these characteristics are not readily available with traditional SAR technologies, such as phased arrays and mechanically steered systems. We show that electronically tuned DMAs can generate steerable, directive beams for traditional stripmap and spotlight SAR imaging modes.
View Article and Find Full Text PDFWe demonstrate a low-profile holographic imaging system at millimeter wavelengths based on an aperture composed of frequency-diverse metasurfaces. Utilizing measurements of spatially-diverse field patterns, diffraction-limited images of human-sized subjects are reconstructed. The system is driven by a single microwave source swept over a band of frequencies (17.
View Article and Find Full Text PDFComputational imaging modalities support a simplification of the active architectures required in an imaging system and these approaches have been validated across the electromagnetic spectrum. Recent implementations have utilized pseudo-orthogonal radiation patterns to illuminate an object of interest-notably, frequency-diverse metasurfaces have been exploited as fast and low-cost alternative to conventional coherent imaging systems. However, accurately measuring the complex-valued signals in the frequency domain can be burdensome, particularly for sub-centimeter wavelengths.
View Article and Find Full Text PDFVestn Ross Akad Med Nauk
February 2016
Interest in the mathematical modeling of the carbohydrate metabolism regulation system increases in recent years. This is associated with a "closed loop" insulin pump development (it controls an insulin infusion depending on the blood glucose level). To create an algorithm for the automatic control of insulin (and other hormones) infusion using an insulin pump it is necessary to accurately predict glycaemia level.
View Article and Find Full Text PDFPatient: Male, 30 FINAL DIAGNOSIS: Hemophagocytic lymphohistiocytosis (LHL) Symptoms: Abdominal pain • fever • hypotension • pancytopenia
Medication: - Clinical Procedure:- Specialty: Infectious Diseases.
Objective: Rare disease.
Background: Hemophagocytic lymphohistiocytosis (HLH) is a result of dysregulated cellular response system.
Proc Annu Symp Comput Appl Med Care
May 1992
An architecture for providing an institutional systems infrastructure is proposed. The architecture permits distributed applications while maintaining an integrated patient database.
View Article and Find Full Text PDFA flagging system to identify blood specimens requiring a blood film review and/or differential leukocyte count is described. Its utility in avoiding unnecessary differential counts particularly in outpatients is given. Significant reductions in workload can be anticipated without deterioration of patient care.
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