| 摘要 |
PURPOSE:To decrease the leak power for the antenna device used at plural frequency bands and thus to enhance the performance of the antenna device by securing the special mirror surface at the periphery of the subreflector. CONSTITUTION:Mirror surface part S1S2 and A1'S2' of the special shapes are formed at the periphery of central mirror surface S1S1' of subreflector 4 featuring a hyperboloid containing focal point F1 and F2. Now, the loci at the point where the electric waves reflected from periphery part M1M2 of main reflector 3 feature the equal phase is referred to as M2M2' respectively. Thus, the locus forms an arc centering on point O on the straight line parallel to the axis of the reflector and passing through point M1. This arc forms curve S1S2. As a result, the electric wave from F1 is refleted on surface S1S' in the high frequency band, and then goes toward mirror surface M1M1' of reflector 3. Thus, the leak power is reduced. While in the low frequency band, the phase error is reduced by reflector 4 of a special shape thus to decrease the leak power. In such way, the leak power can be decreased for the antenna device used at plural frequency bands, thus enhancing the performance of the antenna device. |
