NUFFT_based Synthesis Aperture Microwave Radiometric Circle Array Imaging Inversion

As a new kind of imaging system, Synthetic aperture microwave radiometer used small antenna array to “equivalent” large-caliber real aperture antenna,which reduced antenna processing difficulty and improved the time resolution at the expense of the high system complexity. In order to further reduce the complexity of the synthetic aperture system, circle array and rotating circle array was proposed. But the u –v distribution of circle array is not uniform, the conventional cartesian FFT method could not be used directly for Image inversion. The traditional circle array image inversion method is G matrix algorithm, grid method and pseudo polar coordinates method, all of them have their limitations. In this background, this article studies the rapid and high quality synthetic aperture circle array inversion algorithm.This article first expounds the basic theory of synthetic aperture microwave radiation imaging. The non-uniform fast Fourier transform based on minimum maximum error is applied to synthetic aperture circle array image inversion. Image inversion mathematical model has been established, and some work has been done to balance between speed and image quality of inversion; In this paper, the inversion model based on regularization method is added to effectively suppress the ill-condition of G, which enlarges the noise and error of the image; Calculation of synthetic aperture image inversion is huge, this paper puts forward using conjugate gradient iteration to gradually approximate optimal solution, compared with the traditional algorithm of generalized inverse calculation,the speed is greatly increased.This article also proposed simulation for the inversion algorithm. The simulation results show that the new algorithm can achieve different forms circle array and non-ideal visibility function image inversion, and inversion effect significantly better to traditional methods.