Research On The Brightness Temperature Reconstruction Of Microwave Synthetic Aperture Radiometer

Aperture synthesis uses interferometric techniques to overcome the limitations set by antenna physical aperture while working at lower frequency.The basic theory of synthetic aperture used in microwave radiometer is introduced according to interferometry principle. The principle of general case inversion algorithms is presented. Then Fourier transform inversion algorithm and the inversion algorithm based on G operator are expatiated. The performances of the inversion algorithm based on G operator are compared by means of numerical simulation, the results show the measurement of the G operator is of the most importance to the inversion algorithms.What's more ,the result of the experiment show that the the steppest-descent gradient method is prior to the Moore-Penrose pseudoinverse method.The Van Cittert filter method is prior to the steppest-descent gradient method.Synthetic aperture radiometer inversion algorithm module is designed and programmed by matlab language. The module is adapted to analyse and validate the performance of various inversion algorithms. It is a part of the microwave radiation detecting simulation system.Researched on the key factors of the G operator algorithms of synthetic aperture microwave radiometer .The principle of the measurement of the G operator using approximate point source are presented and the step of the measurement is also given..The effect from multual and imbalance between channels on the measurement of the G operator are analyzed.It shows that the effect is potty. However, the effect of the correlative background noise has great influence to the measurement .Finally, I focus on the antenna major lobe pattern and the background noise .The simulation result shows that if the antenna major lobe pattern is aimed to the objection , we can get the right image ,otherwise , the power of the temperature will be reduced and we can not get the objection in the image.