Novel Gaussian beam method for the rapid analysis of large reflector antennas

A relatively fast and simple method utilizing Gaussian beams (GBs) is devel oped which requires only a few seconds on a workstation to compute the near /far fields of electrically large reflector antennas when they are illumina ted by a feed with a known radiation pattern. This GB technique is fast, be cause it completely avoids any numerical integration on the large reflector surface which is required in the conventional physical optics (PO) analysi s of such antennas and which could take several hours on a workstation. Spe cifically, the known feed radiation field is represented by a set of relati vely few, rotationally symmetric GBs that are launched radially out from th e feed plane and with almost identical interbeam angular spacing. These GBs strike the reflector surface from where they are reflected, and also diffr acted by the reflector edge; the expressions for the fields reflected and d iffracted by the reflector illuminated with a general astigmatic incident G B from an arbitrary direction (but not close to grazing on the reflector) h ave been developed in [I] and utilized in this work. Numerical results are presented to illustrate the versatility, accuracy, and efficiency of this G B method when it is used for analyzing general offset parabolic reflectors with a single feed or an array feed, as well as for analyzing nonparabolic reflectors such as those described by ellipsoidal and even general shaped s urfaces.