Multicoverage shaped reflector antenna designs

The application of the hybrid shaped reflector/array feed approach to the design of multiple contoured antennas is examined. The results show that a hybrid antenna can achieve coverage gain performance comparable to that of a conventional array-fed parabolic reflector design but with a significantly reduced number of feed elements. Increasing the number of feed elements results in a reduced amount of reflector shaping, which in turn leads to better control of the sidelobes and roll-off characteristics. For single and dual beam coverages, improvements can be achieved by imposing constraints on these parameters during the optimization process. For multiple coverages, however, the need to share the reflector shape between several beams restricts the freedom to control the spurious radiation. It appears that for such requirements the sidelobes can be improved only by increasing the number of feed elements to reduce the amount of reflector shaping. This design approach has been used to deal with different multicoverage scenarios including dual-beam AFSAT coverage (C-band), the seven-beam EUROPESAT coverage (Ka-band), and the modified five-beam EUROPESAT supercoverage.<
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