An electrically small compact minimum scattering shaped reflector for a large beam

Shaped reflectors have found a wide variety of geostationary satellite applications in the last few years. Relatively larger beam sizes are required for satellites operating from lower Earth orbits. The larger beams allow the use of relatively smaller antenna sizes to obtain satisfactory gain performance. However, antennas generating larger coverage regions (larger than 30 degrees) are more susceptible to scattering from spacecraft structures and from feed blockage (if a reflector configuration is used). This scattering can be minimized by using a larger offset and a larger reflector size. One of the interesting aspects of shaped reflectors is the possibility of using either converging or diverging solutions, to generate almost identical beam shapes. Intuitively the converging solution appears to be less prone to scattering from adjacent structures and feed blockage. This paper describes an interesting example of a converging shaped reflector designed to generate a very large beam shape (>40 degrees).