Short Range Millimeter-Wave Inverse Synthetic Aperture Radar Imaging
Abstract: Millimeter-wave radar imaging has potential uses in applications such as material analysis and medical in-vivo scanning of tissue. This thesis is about measuring objects using a millimeter wave radar, implement radar imaging algorithms and evaluate the resulting images. The measured objects are plates and rods made of metal and a rod made of acrylic glass (PMMA). The objects are measured using the inverse synthetic aperture radar technique, in which the radar is stationary and and the scene is either moving in a line or rotating in front of the radar, in our case at a few decimeters distance. A pulse generating circuit is used as transmitter and the receiver is a sampling oscilloscope. Multiple imaging algorithms, including backprojection and gridding, are implemented in Matlab. In order to test the algorithms, scripts are implemented to create simulated ideal data from line and rotation measurements. Data for multiple point scatterers is simulated and used in the imaging algorithms to identify if the scatterers are correctly resolved. Using this approach the implemented methods are shown to work as intended. Using strip-map measurement data for two separated metal plates it is shown that an image can be produced where the objects are resolved with correct width, spacing and down-range position. Both the backprojection and gridding algorithms are shown to produce higher quality images with a resolution of less than one centimeter when used in spotlight mode. For gridding it is found that objects with a small distance-to-radius ratio are distorted, which limits the object size for a specific distance.
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