Synthesis technique for scanning and/or reconfigurable beam reflector antennas with phase-only control

Scanning and/or reconfigurable reflector antennas can be conveniently set up by using a hybrid antenna consisting of a reflector illuminated by a small phase-only controlled array feed. However, no general synthesis procedure performing the optimum design of such antennas seems to exist. In the paper a new general and flexible formulation of this synthesis problem is presented together with an iterative solution scheme? which make it possible to determine simultaneously the reflector geometry, the amplitude of the excitation coefficients common to all radiated beams and the phases of such excitations corresponding to each beam. The technique handles general and flexible requirements on the radiated beams (expressed by masks) as well as general constraints on the excitations of the feed array elements (the phase-only control is one of these). Furthermore, it exploits a new choice for the quantity to which the design specifications concerning the radiated field are applied, in order to alleviate the trapping problems encountered in power synthesis. A numerical analysis is performed in order to demonstrate the effectiveness of the approach as well as the possibilities offered by the hybrid reflector antenna configuration.