High frequency techniques for reflector antenna analysis

High frequency (HF) techniques are extensively used for reflector antenna analysis. The ray based optical HF technique dasiageometrical optics (GO)psila enhanced by geometrical theory of diffraction (GTD) predicts accurate radiation pattern but suffers caustics at focal point. On the other hand wave based optical HF technique dasiaphysical optics (PO)psila predicts antenna main lobe and near-in side lobes accurately but is less accurate for far-out side lobes. PO when supported by physical theory of diffraction (PTD) displays improved accuracy for far-out side lobes. The PO technique is slower than GO for radiation pattern calculation of large reflector antennas. In this paper a review of HF techniques is presented. The techniques were applied for radiation pattern analysis of a 30 m earth station antenna @ 40 GHz for radio astronomy. Guidelines for selecting the appropriate HF technique for a given application are presented.