| 摘要 |
An earth station antenna is employed for telecommunicating with a satellite in combination with an automatic tracking apparatus. The antenna is a dual reflector antenna which comprises a main reflector, a sub-reflector and a primary radiator, and the used frequency band of the antenna is at least 1.8 octaves. A parameter t of the antenna, defined by a configuration of the primary radiator is less than 0.3 at the lowest operating frequency. The phase center of the primary radiator, at a low frequency within the operating frequency range, is made to correspond with the focus of the sub-reflector. The above parameter t is defined by: <IMAGE> where: lambda : wavelength in free space, Dh: aperture diameter of the primary radiator, Lh: center axial length from the radiator apex to the radiator aperture plane, and Ls: length from the radiator aperture plane to the bottom surface of the sub-reflector.
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