Wide-Angle Radiation Pattern Calculation of Paraboloidal Reflector Antennas: A Comparative Study.

摘要

In part one, the complete radiation pattern of a symmetrical parabolodial reflector antenna is calculated by high-frequency asymptotic techniques. These techniques are reviewed and the diffraction coefficients, derived for GTD, UTD, APO, and CAPO, are compared. The angle regions in which these methods are valid, are discussed and some associated conflicting statements in literature are cleared up. It is shown that GTD (or UTD) is the most successful method to calculate the scattered field for reflector antennas in wide-angle (away from the antenna axis) regions. To obtain the correct results in the forward- and real-axial region, the PO and EEC method are used, respectively. The results obtained agree well with previous theoretical and experimental work. In part 2, the wide-angle radiation pattern of an offset parabolodial reflector antenna is calculated using the successful GTD (UTD) method. It is shown that there are two far-field caustics in the symmetry plane of the offset configuration: one in the antenna forward-direction and one at a specific angle determined by the offset configuration. In the latter caustic-region the EEC method is used. Outside the symmetry plane specific far-field angles are found where GTD fails; this phenomenon is explained with the help of far-field 'caustic' points. To obtain the complete power pattern, PO is used in the forward axial-region.