Low sidelobe reflector antenna design

Satellite ground stations are typically designed to suppress interference by ensuring that off-axis sidelobe radiation conforms to levels recommended by the ITU. However, significantly lower sidelobes than this are required in systems that may be subject to electronic countermeasures or operate at higher powers. Reflectors are the antenna of choice in most high gain systems, and a number of different configurations may be shown to have the potential for low sidelobe performance. This paper highlights the critical design trade-offs and limitations of such antennas, with emphasis on the practically realisable performance. The systems considered have aperture diameters in the range 4 to 7 metres and are aimed at a requirement for a transportable ground station capable of rapid deployment. Realising a low sidelobe performance relies strongly on maintaining a highly accurate reflector surface; the antenna structural design is therefore very important. Particular attention is given to reflector surface tolerances and the control of highly correlated surface distortions. In this respect, a concurrent approach to electrical and mechanical aspects of the design is essential