Research on Millimeter Wave Imaging with Scanning Array
|School||Harbin Institute of Technology|
|Course||Electromagnetic Field and Microwave Technology|
|Keywords||millimeter wave imaging apparent temperature array scanning quasi-optics|
Millimeter wave imaging technology is widely used in security scanning at airports, aircraft landing navigation, military detection, medical diagnosis and so on, especially for security scanning, millimeter wave has inherent advantages due to its adequate wavelength. Compared with infra-red ray, millimeter wave has longer wave length, so the diffraction in millimeter wave is apparent; while millimeter wave has shorter wave length than centimeter or other low frequency wave, so system working in millimeter wave region has higher resolution. Researchers in many countries have been engaged in this technology, and commercial products for airport security scanning had been put forward around the year of 2000. Research in our country is still at the primary stage, so it is urgent to accelerate the steps.This dissertation focuses on near-field millimeter wave imaging technology and systems. It includes deep study on basic principle and structure, array arrange of antennas, scanning method, quasi optics analysis and design method, theoretical analysis and numerical simulation of imaging with artificial noise, and imaging experiment both indoor and outdoor.First, typical millimeter wave imaging systems in the world was introduced, the principles and key technologies were analyzed, which provided valuable ideas for research in this work. Second, basic principle was studied in details, and some theoretical analysis was taken for engineering design. The structure and key parameters were discussed, and method of the designing was fixed. Third, contradiction between thermal sensitivity and spatial resolution was discussed, which help to determine the array arrangement and the scanning method. Forth, basic theoretical quasi optics was studied, and one engineering design method for quasi optics was proposed. Based on this method, the structure parameters were determined, and were examined using simulation tool. Fifth, theoretical analysis and numerical simulation were taken for millimeter wave imaging with artificial noise illumination, which could benefit the resolution even with an ordinary receiver. At last, experiments with one receiver were taken both indoor and outdoor. Results shows that artificial noise is valid for current system, and relation between spatial resolution and antenna aperture is demonstrated.