Communications: radio wave antennas – Antennas – With means for moving directive antenna for scanning,...
Reexamination Certificate
2000-01-28
2001-10-30
Wong, Don (Department: 2821)
Communications: radio wave antennas
Antennas
With means for moving directive antenna for scanning,...
C343S882000, C343S890000
Reexamination Certificate
active
06310582
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an antenna system suitable for a communication system using a non-geostationary satellite such as a low orbit satellite or the like.
2. Description of the Prior Art
FIG.
1
and
FIG. 2
show the antenna system used for the communication with a conventional non-geostationary satellite. Conventionally, with this kind of antenna system, as shown in
FIG. 1
, a parabolic antenna
1
is attached to a support
103
having at both ends an elevation angle adjusting mechanism
101
adjustable in the angle Y (angle of elevation) from the horizontal direction and an azimuth angle adjusting mechanism
102
adjustable in the angle X (azimuth angle) in the horizontal direction, via the elevation angle adjusting mechanism
101
.
Therefore, with the conventional antenna system, the elevation angle adjusting mechanism
101
and the azimuth angle adjusting mechanism
102
of the antenna are provided for each antenna, and the direction of the antenna is adjusted by adjusting the two adjusting mechanisms
101
and
102
.
Therefore, at the time of communication with the non-geostationary satellite, when the direction of the communication target as seen from a reception point (where the antenna is set up) changes with the lapse of time, it is necessary to have the same number of antenna systems as shown in
FIG. 1
as that of the communication targets, in order to communicate simultaneously with a plurality of communication targets which are in the different direction as seen from the reception point.
However, setting of a plurality of antennas including the direction adjusting mechanism has such problems that not only it simply takes up a lot of space, but also there is a case where antennas become an obstacle to the communication with each other, depending upon the positional relationship of the antennas and the direction of the communication target.
Therefore, there has been proposed an antenna system
1
A having a construction shown in
FIG. 2
in which two antenna systems are placed on the same turntable
105
, and the turntable
105
is rotated so that the antennas
1
a
and
1
b
do not become an obstacle to the communication with each other.
However, with the construction of the antenna system
1
A as shown in
FIG. 2
, five movable adjusting sections are required for adjusting the direction of the antennas
1
a
and
1
b
. Hence, there is a problem that the mechanism becomes complicated and the direction control of the antenna (particularly, the control of the azimuth angle X) becomes complicated.
Moreover, with the satellite communication using a non-geostationary satellite, since the position of the target satellite to be communicated with as seen from the reception point on the ground changes with the lapse of time, it is necessary to follow the target satellite and direct the antenna accurately to the satellite for continuing the communication (for example, see Japanese Patent Application Laid-open Hei 9 No. 321523).
When the satellite used for the communication is to be replaced, an operation for searching and acquiring a new satellite is necessary. Even if the orbit information of the satellite is known and estimate of the position of the satellite is possible by means of calculation, there is a subtle difference between the calculated value and the actual value, hence follow up and acquisition of a satellite cannot be done so easily by means of an antenna having a high directivity used in a ground station of the satellite communication.
Therefore, an auxiliary antenna for acquiring and following a satellite having a Low directivity compared to an antenna for communication (hereinafter referred to as a “pilot antenna”) is provided in addition to the antenna for communication, and the actual position of the satellite is acquired by using the pilot antenna in advance, at the time of adjusting the direction of the antenna for communication.
However, even if the pilot antenna is used, the direction control mechanism of each antenna is independent and the set up position of the two antennas are different. Hence, when it is tried to direct the antenna for communication to the same direction as that of the pilot antenna which has acquired a satellite, directional control of the antenna becomes complicated.
SUMMARY OF THE INVENTION
In view of the above described problems in the prior art, the object of the present invention is to provide an antenna system which realizes a construction of antennas in which a plurality of antennas do not become an obstacle to each other at the time of communication, when the communication is set up simultaneously with two mobile bodies such as a satellite, and which realizes the direction (azimuth angle X and elevation angle Y) adjusting mechanism thereof with a simple construction.
Another object of the present invention is to provide an antenna system which can direct the communication antenna to the same direction as that of the pilot antenna which has acquired the target satellite very easily and rapidly, and the directional control can be performed easily so that antennas do not become an obstacle to the communication with each other.
With a view to attaining the above objects, the gist of the present invention is as follows.
The first gist of the present invention is an antenna system comprising: a first rotation mechanism supporting a first antenna rotatably in a first rotation direction centering around a first axis; a second rotation mechanism for supporting a second antenna rotatably in the first rotation direction centering around a second axis running along or in parallel to the first axis; an elevation angle adjusting mechanism for rotatably supporting the first and second rotation mechanisms commonly in a second rotation direction, centering around a third axis different from the first axis and the second axis; and an azimuth angle adjusting mechanism for rotatably supporting the elevation angle adjusting mechanism in a third rotation direction, centering around a fourth axis different from the first axis and the third axis; wherein the first rotation mechanism is provided in a first area partitioned by a plane containing the third axis and running in parallel to the fourth axis, and the second rotation mechanism is provided in a second area opposite to the first area.
The second gist of the present invention is an antenna system according to the first gist, characterized in that the first and second axes are provided symmetrically to a plane containing the fourth axis and running in parallel to the third axis.
The third gist of the present invention is an antenna system according to the first gist, characterized in that the third and fourth axes intersect each other, and the first and second axes are provided point-symmetrically with respect to an intersection of the third axis and the fourth axis.
The fourth gist of the present invention is an antenna system according to the first gist, characterized in that the third and fourth axes are orthogonal to each other, and the first and second axes are orthogonal to a plane determined by the third and fourth axes.
The fifth gist of the present invention is an antenna system according to the first gist, characterized in that the first and second axes penetrate the center of gravity of the respective antenna.
The sixth gist of the present invention is an antenna system according to the first gist, characterized in that the first antenna is constituted of a planar antenna, and the first axis penetrate the planar antenna bilaterally symmetrically.
The seventh gist of the present invention is an antenna system according to the first gist, characterized in that a third rotation mechanism is provided for supporting rotatably one or more antennas in the first rotation direction centering on the first axis.
The eighth gist of the present invention is an antenna system according to the first gist, characterized in that the first antenna comprises a spherical radio lens and a primary radiator for transmitting and receiving
Kobayashi Akito
Okamura Masahiro
Satou Ken
Taira Midori
Uetake Tatsuya
Alemu Ephrem
Sharp Kabushiki Kaisha
Wong Don
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