COMPARISON OF PO AND PTD ANALYSES OF OFFSET REFLECTOR ANTENNA PATTERNS

Physical optics (PO) have been extensively used in radiation pattern analysis of offset parabola. Physical Theory of Diffraction (PTD) proposed later has better accuracy. This paper presents an analytical/numerical comparative study of these methods to demonstrate the limitations of PO. PO envelope errors in co-polar patterns are expressed as functions of antenna parameters. Serious PO errors in cross polarization prediction are pointed out for antennas with cross-polar suppressing feeds polarized in the plane of asymmetry.