Communications: radio wave antennas – Antennas – Spiral or helical type
Patent
1997-12-17
1999-07-27
Wong, Don
Communications: radio wave antennas
Antennas
Spiral or helical type
343853, H01Q 136
Patent
active
059298243
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to antenna elements, typically for use on satellites.
BACKGROUND OF THE INVENTION
Antenna elements such as those of the present invention are used particularly in group antennas for satellites. Such antennas should have a good polarization purity. That is, such antennas should obtain a low amount of radiation of non-desired polarization and a high amount of radiation having desired polarization. At the same time there is a need for broadband such antennas should obtain the antenna will be able to emit and receive microwave signals within a relatively wide frequency range. If the frequency range is limited to one or more narrow bands, the polarization purity itself can be improved but only at the sacrifice of the broadband characteristics.
SUMMARY OF THE INVENTION
The purpose of the present invention is to provide an antenna element of the kind discussed above, which permits both a high polarization purity and broad band properties. The present invention relates to an antenna element comprising a ground plane and a conical support of a dielectric material. A bottom portion of the conical support is attached to the ground plane and supports first to fourth radiation means having the shape of helical wires arranged symmetrically around and carried by the support. The radiation means are, at their exterior, lower ends attached to the ground plane. For transmission, each radiation means is provided, at their upper, interior parts, through an individual coaxial cable with an individual microwave signal, so that two orthogonal polarizations that preferably are circular are generated by the emitted radiation.
According to the present invention such an antenna element is primarily characterized in that. for transmission, a distribution network is arranged to divide the incoming signal into four subsignals that are offset in phase in relation to each other. Each signal is provided to one of the first to fourth radiation means mentioned above. Adaption means are arranged to adapt the output impedance of the distribution network to the input impedance of the radiation means, so that it is substantially independent of the actual microwave frequency used within a relatively wide frequency range.
In an advantageous embodiment of the antenna element according to the present invention, the adaption means comprises four separate conductors that constitute capacitive loads, which, with their ends are connected to the upper ends of a corresponding radiation means.
In an alternative embodiment, the adaption means comprises a metal block constructed to include four interior channels through which the respective conductor in the coaxial cables extend substantially centrally.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention will be described in the following in greater detail with reference to the accompanying schematic drawings in which:
FIG. 1A shows an elevational view, which partially is a sectional view, of an antenna element according to the present invention,
FIG. 1B shows the antenna element of FIG. 1A as seen from above,
FIG. 2A shows an elevational view, which partially is a sectional view, of an adaption means,
FIG. 2B shows the adaption means of FIG. 2A as seen from above,
FIG. 3A shows an elevational view, which partially is a sectional view, of an alternative adaption means,
FIG. 3B shows the adaption means of FIG. 3A as seen from above,
FIG. 4 shows the input impedance Z of the radiation means as a function of the frequency in GHz for an older antenna element, graph I, and an antenna element according to the invention, graph II.
DETAILED DESCRIPTION OF THE INVENTION
In FIGS. 1A and 1B a ground plane having the shape of a circular metal plate has the reference numeral 1. A conical support 2 of a dielectric material is, with its bottom, portion attached to the ground plane. The support is constructed from two planes arranged orthogonally in relation to each other and carries at its geometric envelope surface first to fourth radiation means having the sh
REFERENCES:
patent: 3188643 (1965-06-01), Dyson et al.
patent: 3633210 (1972-01-01), Westerman
patent: 4008479 (1977-02-01), Smith
patent: 4766444 (1988-08-01), Conroy
patent: 5346300 (1994-09-01), Yamamoto et al.
patent: 5349365 (1994-09-01), Ow et al.
patent: 5479182 (1995-12-01), Sydor
patent: 5485170 (1996-01-01), McCarrick
Bengtsson Par
Johansson Jan-Olof
Phan Tho
Saab Ericsson Space AB
Wong Don
LandOfFree
Antenna element, conically helical, for polarization purity with does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Antenna element, conically helical, for polarization purity with, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Antenna element, conically helical, for polarization purity with will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-884149