Predicting influence of the rest spherical surface on the instantaneous parabolic surface of multi-beam for radio astronomy

The instantaneous parabolic antenna deformed from an active spherical main reflector in real time has been proposed for years to achieve space scanning without rotating the giant body of radio telescope and enable the realization of wide bandwidth, high sensitivity, full polarization capability and multiple beams by standard feed design. When the reflector is operating in a wide bandwidth, the inevitable energy leaking into the rest spherical surface will influence the illuminated parabolic surface. When the feed moves along the focus plane to track the radio source, the influence varies with the changing leakage energy. In order to predict this influence, a dual-polarization, 19-beam feed with relative bandwidth of 32% is designed and the calculation principles of the influence is derived, and simulated results of the independent illuminated parabolic reflector and the hybrid reflector are compared with each other to evaluate the influence.