A broadband omnidirectional microwave antenna with decreased sky radiation and with a simple means of elevation-plane pattern control

摘要

An omnidirectional microwave antenna comprises a paraboloidal reflector 12 disposed above the ground and facing downwardly with a substantially horizontal aperture and a substantially vertical axis. A vertically oriented feed horn 10 is located below the paraboloidal reflector 12 on the axis of the paraboloidal reflector 12 and has a phase center located near the focal point F of the paraboloidal reflector 12. A conical reflector 11 extends downwardly away from the periphery of the feed horn 10 for reflecting radiation received vertically from the paraboloidal reflector 12 in a horizontal direction away from the conical reflector 11, and for reflecting horizontally received radiation vertically to the paraboloidal reflector 12. A radome 15 extends downwardly from the outer periphery of the paraboloidal reflector 12 and includes an absorber material (16, fig. 2) for absorbing radiation propagated laterally from the feed horn 10 and the conical reflector 11 above the aperture of the feed horn 10. The absorber material 16 may extend fully across the aperture of the antenna in a sector to control the azimuthal directivity of the antenna (fig. 8).