The screening systems in the airports are using two technologies, x-ray backscattering and millimeter wave radar. The millimeter wave radar is a more desirable technology since it has depth information and is not an ionizing radiation, although the resolution in the millimeter wave frequency is not as high as x-ray frequency. However to have good detection from the millimeter wave radars, different methods has been used to improve the resolution of the images reconstructed by the radar. ææHere we improve the resolution of the images by using a regularization method. The regularization method is used in the process of image reconstruction rather than a post-processing procedure, so it is more effective in dealing with the artifacts resulted from limitations or noise in the data. We find the best regularized image of all the infinite solutions of the imaging system by introducing a priori information about the reconstructed images in the form of regularization terms. This method also deals with the ill-posed nature of the synthetic aperture radar (SAR) imaging system. The results are shown for some examples and compared to the conventional SAR reconstruction method.