Communications: radio wave antennas – Antennas – With means for moving directive antenna for scanning,...
Reexamination Certificate
1999-10-29
2001-04-17
Phan, Tho (Department: 2821)
Communications: radio wave antennas
Antennas
With means for moving directive antenna for scanning,...
C343S757000, C343S840000, C343S872000
Reexamination Certificate
active
06218999
ABSTRACT:
BACKGROUND OF THE INVENTION
The field of the invention is that of antenna systems, in particular for pointing at non-geostationary satellites. To be more precise, the present invention concerns a system with at least two antennas capable of pointing independently of each other in any direction within a solid angle.
In the context of the present invention, a terrestrial transmission system is considered, e.g. as installed on the roof of a building. The system includes at least two antennas, for example parabolic antennas, designed to communicate with, i.e. to transmit to and/or receive from, non-geostationary satellites. The antennas are close together (i.e. co-located) for reasons of overall size and/or to reduce the lengths of the connections to a single modem and/or so that they can be located under the same protective radome. The two antennas can be steered independently of each other in azimuth and in elevation, i.e. each is mounted on a separate support.
The problem that arises with a system of the above kind is that one antenna may mask the other antenna(s), as shown in
FIGS. 1 and 2
, because of the position of the satellites, and in particular when their elevation is low. The antennas are considered to be located in the same horizontal plane, i.e. at the same height.
In
FIG. 1
, which is a simplified plan view of a system with two co-located parabolic antennas, the two antennas
10
and
11
are pointing in opposite directions and neither of them can transmit or receive signals because they mask each other. In
FIG. 2
, the antennas
10
and
11
are pointing in the same direction and the antenna
11
is therefore masking the antenna
10
.
To avoid such masking, it is possible to move the antennas a greater distance apart, the requirements for compactness are then no longer satisfied. Also, it is no longer possible to protect them by a common radome.
One object of the present invention is to remedy the above drawbacks.
SUMMARY OF THE INVENTION
To be more precise, one object of the invention is to provide an antenna system including at least two antennas each of which is capable of pointing independently of the other(s) in any direction within a solid angle, the system enabling the antennas to be colocated without masking each other.
The above object, and others that become apparent below, are achieved by an antenna system including at least two antennas, each of the antennas being capable of pointing independently of the other(s) in any direction within a solid angle, the system being characterized in that the antennas are mounted on a common support cooperating with rotation means for rotating the common support, the rotation means being activated to prevent masking of one of the antennas by another of the antennas.
Rotation of the common support enables the antennas to be disposed beside each other for aiming in the same direction or opposite directions.
The antennas used can be circular or elliptical parabolic antennas, i.e. passive antennas, or active antennas made up of patches.
The rotation means are preferably adapted for rotation of ±45° relative to a median position.
The antenna system is advantageously covered by a radome and the invention applies in particular to tracking non-geostationary satellites.
REFERENCES:
patent: 2408825 (1946-10-01), Varian et al.
patent: 3893123 (1975-07-01), Bieser
patent: 4791428 (1988-12-01), Anderson
patent: 5089824 (1992-02-01), Uematsu et al.
patent: 5245348 (1993-09-01), Nishikawa et al.
patent: 5420598 (1995-05-01), Uematsu et al.
patent: 0 579 407 A1 (1994-01-01), None
patent: 0 600 699 A1 (1994-06-01), None
patent: 0 707 356 A1 (1996-04-01), None
patent: WO 88/09066 (1988-11-01), None
Bousquet Jacques
Menard Pierre
Alcatel
Phan Tho
Sughrue Mion Zinn Macpeak & Seas, PLLC
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