Imaging Simulation Of Mixing Aperture Antenna Of Microwave Aperture Synthetic Radiometer

Microwave aperture synthetic radiometer(ASR)uses the sparse small aperture antenna array to synthesize the equivalent large real aperture to improve the spatial resolution,which has a good prospect in the remote sensing of the earth.In order to improve the sensitivity of the Microwave aperture synthetic radiometer,there are two ways,one of the way is to increase the unit antenna diameter.Since diameter of the antenna is limited by the antenna array element spacing.It is difficult to expand the diameter of an antenna in the array,which is in the densely arranged part.However,in the sparse part of the array,we can increase the antenna diameter.In this thesis,based on the one-dimensional minimum redundant antenna array,a mixed aperture antenna array scheme is proposed,which uses small-diameter antennas in the densed a arranged part,and the large-diameter antenna is used in the relatively sparse part of the array.Firstly,a one-dimensional minimum redundant antenna array is generated,and then the antenna pattern of different diameter is introduced at different array positions.Finally,the brightness temperature distribution image of the original scene is obtained by Fourier transform inversion.But the brightness temperature image fluctuates greatly and the distortion is serious.After analysis,we find the reason,why the brightness temperature image fluctuates greatly,is that the Fourier transform inversion method is an ideal inversion method based on the case where all the unit antennas have the same antenna pattern.Because the array antenna pattern of the mixing aperture antenna array is different,The brightness temperature image quality obtained by the inversion method is uncertain.However,if we still want to get the ideal bright temperature image,there are two methods,one is to eliminate the difference between the unit antenna patterns,and then use Fourier transform method to reconstruct the bright temperature image;the second one is directly using generalized inverse G matrix inversion method to inversion the bright temperature image.In this paper,the second method is adopted to reconstruct the bright temperature image.The G matrix inversion process involves the calibration of the bright temperature image.The bright image obtained by the generalized inverse G matrix inversion method basically restores the original scene,and the inversion effect is much better.