| 摘要 |
PURPOSE:To improve the wide-angle radiation characteristics by attaching a radio wave shielding plate made of a metal or a dielectric substance along the edge of a secondary reflector and attaching a radio wave absorber to said shielding plate. CONSTITUTION:A secondary reflector 2 and a main reflector 3 have a rotary concave oval surface and a rotary concave paraboloidal surface respectively and are set symmetrical to an axis 6 in terms of revolution. The phase center F1 of the primary radiator 1 is set inside both reflectors 2 and 3. A radio wave shielding plate 4 is set around the reflector 2 in such a range that does not disturb the travel of radio waves. A radio wave absorber 7 is attached inside the plate 4 to absorb the radio waves leaking out around the reflector 2 as well as the radio waves which are radiated in the opposite direction to the axis 6 at the edge of the reflector 2 owing to the diffracted wave at said edge. In this way, the wide- angle radiation characteristics of an antenna are improved. In such a constitution, both the length of the plate 4 and the size of the absorber 7 can be reduced compared with the structure where the absorber is set around the reflector 3. |
