Spatial and angular domain analysis of the near-field radiation of electrically large apertures with non-uniform field

According to the equivalence principle, the design of the compact range (CR) reflector can be transformed into the design of its aperture. Therefore the analysis of the CR performance variations caused by the mechanical and electrical defects can be transformed into the analysis of the aperture near-field in the spatial and angular domains. Based on a square aperture and a well-designed serrated-edge aperture, the near-field characteristics have been analysed when typical amplitude and phase non-uniformities have been induced in the aperture. The aperture field convolution method and plane wave spectrum method have been adopted. Simulation results have been presented and compared in detail. The width and height of the apertures are 150 wavelengths in free space. The amplitude and phase non-uniformities discussed include: amplitude taper, serrated edge, periodic amplitude, periodic phase, linear amplitude, linear phase, local amplitude mutation and local phase mutation. The conclusions provide references for CR design, testing, measurements and antenna tolerance analysis.