Near field image reconstruction algorithm of synthetic aperture radiometer based on partial differential equations

Since the Fourier imaging theory of the synthetic aperture interferometric radiometer (SAIR) is unavailable under near field conditions, a nontrivial numeric image reconstruction algorithm based on the local adaptive partial differential equations (PDE) was proposed. Based on the prior information of the desired brightness temperature distribution, an isotropic diffusion was applied at the image background areas to denoise, whereas adaptive diffusion was performed at image target areas to maintain image edges. It was demonstrated by near-field simulation that this algorithm is effective in lowering the image reconstruction errors caused by visibility measurement noise. Imaging experiments were conducted on the two-dimensional 8 mm band SAIR BHU-2D-U, and the advantages of this method were proved.