Communications: radio wave antennas – Antennas – Balanced doublet - centerfed
Reexamination Certificate
1999-06-03
2001-01-16
Wimer, Michael C. (Department: 2821)
Communications: radio wave antennas
Antennas
Balanced doublet - centerfed
C343S840000
Reexamination Certificate
active
06175338
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to antennas of the type having a parabolic reflector element for concentrating microwave radiation, transmitted from a feed arrangement located at the focal point of the reflector, into a collimated microwave beam. More particularly, the invention relates to feed arrangements for such antennas.
Parabolic reflector antennas are used for directional radio and satellite transmission. The parabolic reflector can be a grid structure or a solid structure.
The reflectors of the antennas are normally illuminated by feed arrangements in the form of either a buttonhook feed horn or a dipole radiator with a subreflector. Horn fed antennas are normally used for frequencies above 3 GHz, and dipole radiator arrangements are used for frequencies below 3 GHz.
Above 3 GHz, required dimensions of the horn feed structure of a horn fed antenna are such that the minimum parabolic reflector size is typically limited to about 1.8 meters. Below this reflector size the antenna suffers aperture blockage which degrades the radiation pattern of the antenna and renders it less efficient.
Known dipole feed arrangements are commonly made from discrete machined metallic components, and moreover, require a separate balun arrangement.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a cost effective, easily manufactured dipole feed arrangement for a reflector antenna for operation at frequencies above 3 GHz.
It is a further object of the present invention to provide a dipole feed arrangement for a reflector antenna, that has an integral balun.
It is a still further object of the present invention to provide a dipole feed arrangement for a reflector antenna, that can be implemented using printed circuit board (PCB) techniques.
According to the invention there is provided a dipole feed arrangement for a parabolic reflector antenna, said arrangement comprising a planar member of insulating material supporting on one side thereof a first pattern of conductive material forming at least two spaced parallel dipole elements of pre-determined dimensions whose respective intermediate parts are connected by a single conductive element provided with two opposite collinear slots whose electrical lengths are approximately one quarter of a wavelength at said antenna's operating frequency, said slots bifurcating respective dipoles, said conductive element including a first connection zone for connection of a coaxial feeder cable's outer conductor, said slots and said conductive element forming part of an integral balun means, wherein said conductive element further includes at least two spaced notches of predetermined depth and location on one side of the said conductor element, and wherein a second pattern of conductive material is supported on the other side of said planar member, forming a transmission line element provided with a second connection zone for connection to said coaxial feeder cable's inner conductor, said first connection zone and said second connection zone being coaxial, said transmission line element having two spaced through-connection means each of which communicates with a pre-determined part of a respective dipole element.
REFERENCES:
patent: 5229782 (1993-07-01), Hemmie et al.
Alcatel
Sughrue Mion Zinn Macpeak & Seas, PLLC
Wimer Michael C.
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