Browsing by Subject "Radar imaging"
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Item Design and application of microstrip leaky wave antennas for radar sensing(2014-08) Yang, Shang-Te; Ling, HaoThis dissertation investigates the application of the frequency-scanned beam of a microstrip leaky wave antenna (LWA) to track humans in the two-dimensional (2-D) range-azimuth plane. The history, operating principles and frequency-scanned properties of a microstrip LWA are first reviewed. The basic concept of using a microstrip LWA to track humans is verified by designing, building and testing a broadband microstrip LWA, developing the necessary processing algorithm, and collecting data using a vector network analyzer. A number of topics are then investigated to further advance the concept. First, the idea of combining the frequency-scanned antenna with a short-pulse ultra-wideband (UWB) radar is developed to realize a portable, real-time system for human tracking. The radar concept and the components of the system are discussed in detail. Line-of-sight and through-wall measurements of a human subject are carried out to demonstrate the performance. Second, a new LWA structure is proposed to achieve a narrower azimuth beam, which requires both a small leaky-wave attenuation constant and a long aperture. The transverse resonance method (TRM) is applied to analyze the proposed structure and the results are verified with measurements of a built prototype. Third, a new signal processing technique, compressive sensing, is applied to further improve the resolution in both the azimuth and down range dimensions. The technique is tested with simulation and measurement data and is shown to produce sharper target responses in both the down range and azimuth dimensions. Lastly, the radar cross-section (RCS) of a microstrip LWA is studied. The antenna mode scattering and structural mode scattering are modeled separately. A ray picture is provided to explain the observed time-domain features using the group delay of the leaky wave.Item In-situ, high-resolution radar imaging of dynamic targets using an ultra-wideband radar(2016-08) Li, Chenchen Jimmy; Ling, Hao; Yilmaz, Ali; Hamilton, Mark; Santoso, Surya; Lin, AdrianThis dissertation investigates in-situ, high-resolution radar imaging of dynamic targets using an ultra-wideband (UWB) radar. Three challenging classes of dynamic targets are investigated: wind turbines, vehicles, and small consumer drones. First, the measurement and processing methodologies are developed to capture the inverse synthetic aperture radar (ISAR) image of an operating horizontal-axis wind turbine. Measurement data of a small three-blade wind turbine are collected using a UWB radar, and the measured signatures are compared to simulation results based on physical optics. The backscattering phenomenology is examined in the sinogram, spectrogram, and ISAR image domains. The same methodologies are then applied to generate the in-situ ISAR imagery of an 18-blade windmill and a 1.7 MW utility-class wind turbine. Next, the radar signatures of a vertical-axis wind turbine are studied. Measurement and simulation are carried out for a 1.5 m tall Darrieus-type turbine model. Interpretation of the dominant backscattering mechanisms is carried out. Subsequently, the radar signatures of a 112 m tall turbine are examined using simulation. Second, wide-angle ISAR imaging of vehicles is investigated. Measurement data of moving vehicles are collected using a stationary roadside UWB radar. The generated baseline ISAR images show a clear distinction between different-sized vehicles. The images are further focused through motion compensation using a p-norm minimization. The resulting images are well focused and correspond closely to the physical dimensions of the vehicles. Third, the ISAR imaging of small consumer drones is considered. Laboratory measurement is conducted first, where the drones are rotated on a turntable and the backscatterered data are collected over a wide frequency band to form high-resolution images. The effects of frequency band, aspect, polarization, dynamic blade rotation, camera mount, and drone types are examined. Subsequently, ISAR imaging of in-flight drones, from data collected using a stationary UWB radar on the ground, is demonstrated. Finally, synthetic aperture radar (SAR) imaging using a small drone as the radar platform is explored. The entire system including a UWB radar, antennas, a camera, and a single-board computer fits on the small drone and is controlled through a Wi-Fi connection. Both the side-looking and downward-looking SAR scenarios are presented.