一维镜像综合孔径的近场相位校正方法

Near-Field Phase Correction Method for One-Dimensional Mirrored Aperture Synthesis

镜像综合孔径微波辐射成像的原理基于远场条件推导,不适用于近场成像。为了解决近场条件下的镜像综合孔径成像问题,本文推导了近场双天线互相关表达式,发现近场双天线互相关可以表示为远场双天线互相关与近场相位因子的乘积。校正该相位因子后,即可使用反余弦变换进行近场亮温重建,从而解决了近场条件下的成像问题。本文提出了两种基于外部点源的近场相位校正方法,并分别对点源目标及展源目标进行了仿真,仿真结果表明:校正后的亮温重建误差较小,从而验证了这两种方法的有效性。

The imaging principle of mirrored aperture synthesis(MAS), which is derived based on far-field conditions, is not suitable for near-field imaging. In order to solve this problem, the expression of the dual-antenna cross-correlation under near-field conditions is derived, which is a product of the far-field dual-antenna cross-correlation and the near-field phase factor. After eliminating the near-field phase factor, the inverse cosine transform can be used to reconstruct the brightness temperature under near-field conditions. In this paper, two near-field phase correction methods based on external sources are proposed. Simulations on the point source target and the extended source target are carried out, respectively. After the near-field phase correction, the error of the brightness temperature reconstruction becomes small, which verifies the effectiveness of these methods.