This work presents a shaping method for offset dual reflector antennas. The shaping method for an offset dual reflector antenna has been studied by many authors [l]-[3], since its geometry provides blockage free aperture distribution. While those shaping techniques are based on solving partial differential equations, the method in this work solves nonlinear equations to obtain an electrically small local dual reflector surface section. A shaped offset dual reflector antenna surface is created by combining them and the desired aperture distribution is controlled by the location of caustic for each local dual reflector system. This idea was first introduced in [4] for two dimensional dual reflector antenna and extended to the circularly symmetric case as in [5]. The same approach is used for the offset dual reflector antenna on a 3D basis in this work. In shaping dual reflectors, the principles of geometrical optics (GO), such as conservation of power and Snell's law, have been widely used as in [1]-[3]. In addition, geometrical properties of parabolic main reflector and either elliptic or hyperbolic subreflector surface are used in this work to formulate the shaped surface equations.
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