Synthetic Aperture Microwave Radiometer Spatial Frequency Sampling

He Baoyu (Aerocraft Design)Directed by Wu JiSynthetic aperture technology in radio astronomy is introduced into microwave radiometer since 1980's. Synthetic aperture radiometer applies the interferometric principle to sample in the spatial frequency domain and retrieves the image by Fourier or other numerical transformation. Through this technique, a substantial reduction can be obtained compared to a conventional radiometer, at the same time, the contrary between the space resolution and system volume is well solved. As a crucial consideration of the synthetic aperture radiometer system design, the choice of spatial frequency samplings is always the issue among people's discussion. This paper studies the least redundant solutions of two-dimensional array system by using the simulated annealing algorithm. Two ideal thinning solutions for the two-dimensional circle array were discussed intensively in this paper. One solution uses half-circle configuration with very much reduced number of elements and taking an image by rotating the array; the other selects element positions around the full circle to provide a roughly uniform coverage in the spatial frequency domain.Furthermore, another two important parts of the design of synthetic aperture radiometer are also discussed in this paper. One is the optimizing of the distribution of receiving elements; the other is the image retrieving algorithm. The results of numerical simulations and field experiments show that the theory of aperture synthesis is feasible.