Optimum shape of dipole-fed reflector antennas

Deals with the optimisation of dipole-fed reflector antennas which predominately are used in the UHF band. The main object of the shaping process, which simultaneously includes dipole and reflector, is to obtain radiation patterns that are frequency independent within a certain bandwidth. Both dipole and reflector are shaped in three dimensional space in order to exploit all degrees of freedom which have any influence on the radiation pattern. For the analysis and the computation of farfields the method of moments NEC program is used. The reflector is approximated by wire grid modelling. Optimisation methods applied are the Simplex Method, the conjugate gradient method and the quasi-Newton method. In order to find an appropriate optimisation method, the topography of the quality criterion at first is analysed