Wide-angle radiation pattern calculation of paraboloidal reflector antennas : a comparative study

In the first part of the report, the complete radiation pattern of a symmetrical paraboloidal 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 forwardand rear-axial region, the PO and EEC method are used, respectively. The results obtained agree well with previous theoretical and experimental work. In the second part of the report, the wide-angle radiation pattern of an offset paraboloidal 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~irection 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. Chen, J. and 1'.J.I. de l1aagt, M.lI.A.J. Herben I"lIDE-ANGLE RADIATIOll PA'fTERN CALCULATION OF PARABOLOIDAL llEFLEC·rOR ANTENNAS: A COI·U'ARATI VE STUDY. Faculty of ~lectrical Engineering, Eindhoven University of Technology, The Netherlands, 1991. EUT Report 91-E-252 Ad<lress of the authors: Telecommunications Division, Faculty of Electrical Engineering, Eindhoven University of Technology, P.O. Box 513, 5600 Jill EINDHOVEN, The Netherlands Acknowledgements Firstly, the authors would like to thank the Chinese Government and Chengdu Aircraft Company for their financial support and for giving mr. Chen the opportunity to work at the Eindhoven University of Technology for the period from September, 1989 to December, 1990. Furthermore, we want to thank prof.dr.ir. G. Brussaard for his continued interest. Finally, we want to thank dr. P.R. Attwood for reading and correcting the grammar of the original version of this report. TABLE OF CONTENTS Abstract Acknowledgements