Offset-fed radial-rib umbrella reflector antenna analysis using Zernike polynomials

Zernike polynomials were used to perform the physical optics scattering integral of umbrella reflectors. A computationally efficient numerical procedure was obtained for the umbrella reflector. To demonstrate the method, it was applied to a typical offset umbrella reflector. The radiation patterns for a focused and a scanned feed are shown. Three patterns are shown superposed: one was computed using a conventional two-dimensional integration, and the other two using the Zernike expansion procedure. The agreement between the Zernike approach and the conventional method is good, provided that enough gore-related expansion terms are included in the computations.<>