Communications: radio wave antennas – Antennas – Plural separate diverse type
Reexamination Certificate
1999-07-22
2001-01-30
Wong, Don (Department: 2821)
Communications: radio wave antennas
Antennas
Plural separate diverse type
C343S895000, C343S702000
Reexamination Certificate
active
06181286
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to an integrated antenna and more particularly, the present invention relates to a dual mode antenna system.
BACKGROUND OF THE INVENTION
In the prior art, satellite antennae, terrestrial antennae and integrations of these two have been proposed. Referring initially to the satellite antennae prior art, the quadrifilar helix has been known for several decades. This antenna includes four helical windings fed in phase quadrature. This arrangement provided several characteristics particularly well suited to satellite communications including a hemispherical omnidirectional radiation pattern with excellent circular polarization throughout the radiation pattern as well as compactness and structural simplicity.
For mobile terrestrial communications, the same omnidirectional requirement exists, but the radiation pattern need only to be omnidirectional at the horizon due to the constraints of terrestrial communications on the position of the user relative to base stations. The most common arrangement in the art is the monopole antenna comprising a simple wire above a ground plane.
More contemporary designs of antennae have included dual mode systems. These systems accommodate satellite and terrestrial antennae. These systems present significant design problems particularly with respect to isolation between the two antennae, signal blockage minimization and compactness.
The prior art systems attempted to alleviate the design difficulties by simply placing a satellite antenna and a terrestrial antenna a minimum distance apart such that isolation and blockage requirements were met. Although a generally useful concept, in order to achieve the most desirable performance, a significant separation between the antennae was required. This did not solve the problem of compactness and, in fact, compromised the compactness requirement.
In U.S. Pat. No. 5,600,341, issued Feb. 4, 1997, to Thill et al., there is provided a dual function antenna structure for transceiving in first and second modes.
The apparatus taught in this U.S. patent is a dual frequency single antenna as opposed to a dual mode dual antenna. Accordingly, in the Thill et al. disclosure, there is no teaching with respect to a co-location of two discrete antennae and accordingly, there is no recognition or discussion of the problems encountered when one attempts to co-locate two antennae. The structure provides two feed points for two fields but remains a dual frequency single antenna. This arrangement does not address whatsoever any of the complications inherent in co-location of two antennae such as caging of the signal from antenna to block communication of the co-located antenna.
Further prior art related to the present invention is set forth in U.S. Pat. No. 4,959,657, issued to Mochizuki, issued Sep. 25, 1990. This reference teaches an omnidirectional antenna having a reflector. There is no provision in this reference for the isolation of a monopole antenna with a quadrifilar antenna and accordingly, this reference simply teaches a variation on what is already known in this art.
Moore et al., in U.S. Pat. No. 5,657,792, issued Jul. 22, 1997, discloses a combination GPS and VHF antenna. The combination antenna provides a volute or quadrifilar antenna together with a monopole. Although the elements are provided, there is no co-location between the two antennae which, of course, does not contribute to the compactness of the antenna. By simply providing the combination of the two known antennae in spaced relation, interference problems are not in issue. From a review of the disclosure, it is clear that the Moore et al. reference fails to recognize the value of having a co-located antenna system.
The present invention completely overcomes the limitations in the known art and provides a dual mode antenna system having outstanding performance in a compact system.
SUMMARY OF THE INVENTION
One object of the present invention is to provide an improved dual mode antenna system.
A further object of the present invention is to provide an integrated antenna, comprising:
a quadrifilar antenna; and
a monopole antenna positioned within the quadrifilar antenna and independent of said quadrifilar antenna.
Advantageously, the isolation difficulties inherent with prior art arrangements do not present any concerns in the instant system. In view of the fact that the monopole antenna has a field null in its center, interference or blockage of the monopole signal does not occur, thus allowing the antennae to function as if completely isolated. This feature facilitates collocation of the antennae without any loss in performance.
Another object of the present invention is to provide a method of forming a dual mode integrated antenna, comprising the steps of:
providing a quadrifilar antenna for transceiving circularly polarized fields;
providing a monopole antenna for transceiving linearly polarized fields;
co-locating the monopole antenna within the quadrifilar antenna and independent of the quadrifilar antenna; and
phase coupling the monopole antenna to the quadrifilar antenna.
Having thus described the invention, reference will now be made to the accompanying drawings illustrating preferred embodiments.
REFERENCES:
patent: 4030100 (1977-06-01), Perrotti
patent: 4959657 (1990-09-01), Mochizuki
patent: 5317327 (1994-05-01), Piole
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patent: 5479178 (1995-12-01), Ha
patent: 5546094 (1996-08-01), Egashira
patent: 5583520 (1996-12-01), Thill
patent: 5600341 (1997-02-01), Thill et al.
patent: 5610620 (1997-03-01), Stites et al.
patent: 5650792 (1997-07-01), Moore et al.
patent: 5684672 (1997-11-01), Karidis et al.
patent: 5717409 (1998-02-01), Garner et al.
patent: 5731791 (1998-03-01), Jang
patent: 5812097 (1998-09-01), Maldonado
patent: 5859618 (1999-01-01), Miller, II et al.
patent: 0747990 A1 (1996-12-01), None
patent: 0755091 A1 (1997-01-01), None
patent: 2206243 (1988-12-01), None
patent: 2243724 (1991-11-01), None
patent: 2246910 (1992-02-01), None
patent: 2339969 (2000-02-01), None
patent: WO 97/41621 (1997-11-01), None
patent: WO 98/15029 (1998-04-01), None
patent: WO 99/28989 (1999-06-01), None
Clarke Brian
LaFleur Philippe
Roscoe David
(Marks & Clerk)
Alemu Ephrem
Sharpe Paul S.
Vistar Telecommunications Inc.
Wong Don
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