Broadband omnidirectional microwave antenna for minimizing radiation toward the upper hemisphere

DETAILED DESCRIPTION It is a primary object of the present invention to provide an improved omnidirectional antenna which is a reflector-type antenna capable of operating over a wide frequency band, at relatively high power levels, and at high frequencies.
Specifically, it is an object of this invention to provide such an antenna which is capable of operating at frequencies above 10 GHz, including the 7.
5 to 29.
5 GHz band, and at power levels as high as 2 Kw.
It is another object of this invention to provide such an improved omnidirectional antenna which can transmit and receive signals having either horizontal or vertical polarization.
A still further object of this invention is to provide such an improved omnidirectional antenna which permits field-adjustable beam tilt by simply moving the feed along the axis of the antenna.
A further object of this invention is to provide such an improved omnidirectional antenna which produces a pattern shape that remains stable as the frequency changes.
Yet another object of this invention is to provide such an improved omnidirectional antenna which facilitates the achievement of a shaped elevation beam, which is stable with frequency, and requires only a slight change in the reflector shape.
Yet a further object of this invention is to provide an improved omnidirectional antenna which reduces the amount of radiation toward and into the upper hemisphere so as to avoid interference with satellite communications.
Other objects and advantages of the invention will be apparent from the following detailed description and the accompanying drawings.
In accordance with the present invention, the foregoing objectives are realized by providing an omnidirectional microwave antenna comprising a conical reflector having a surface of revolution defined by a segment of a parabolic curve rotated around the axis of the conical reflector, and a feed horn located on the axis of the reflector.
The center of the aperture of the feedhorn is located substantially at the apex of the reflector