Abstract:

The concept of diagnostic spectrum of aperture near field is presented to describe the near field characteristics of an aperture. The diagnostic spectrums include angular spectrum and time spectrum, which are defined as transformation of spatial and frequency near field in angle and time domains respectively. Theoretical analysis and numerical computation show that the direct and diffractive waves of an aperture can be distinguished by the diagnostic spectrum. Therefore, they can be used to describe the relative diffractive field changes of an aperture while its size,shape and field distribution changed. This is useful for compact range (CR) design. Near field of a 5 m×5 m circular and quadrangular aperture is computed and compared based on aperture field convolution method. It can be deduced that the aperture near field angular spectrum is a product of the aperture field angular spectrum and the spatial network response function angular spectrum. Therefore, the spatial network function acts as a spatial angular spectrum filter.

Key words: diagnostic , spectrum,  , aperture , field,  , near , field,  , convolution , method,  , compact , range