Compact Range Performance Evaluation Using Aperture Near-Field Angular Spectrums

Abstract

For a compact range (CR), the near-field angular spectrum can be obtained by making an inverse Fourier transform of its aperture spatial near field. The characteristics of the aperture design have been carried by the aperture near-field angular spectrum. The direct wave and edge-diffracted waves from the aperture can be separated and distinguished clearly in the angular domain. Therefore, the CR performance can be evaluated and improved accordingly. In this paper, based on the aperture field convolution method and plane wave spectrum (PWS) theory, near-field angular spectrums for different apertures have been computed. The general criteria for the CR aperture design have been discussed. The selections of the whole aperture shape, the serration height, the serration base length, the serration number, and the serration shape (including isosceles and right-angled triangles) have been compared. At last, the near fields of an optimized serrated-edge aperture and an original circular aperture in different transverse planes have been computed and compared. The width and height of the apertures are all 30 wavelengths in free space. In order to suppress the sidelobes, a Chebyshev window with ${- 50} $ dB sidelobes has been adopted in the spatial-angular transform.