JPS5846893B2 - Kahenbe Muhaba Antenna Omochiita - Google Patents

Description

[Detailed Description of the Invention] The present invention is a marine satellite communication system that uses artificial satellites to connect ships to the ground, or ships to ships, by widening the beam width of the antenna when the ship's shaking becomes large. hand,
Method for preventing communication breakdown % type % Vessel movements can be mainly divided into (i) change of direction, ([1) pitching, and G11) rolling.

One of the goals of conventional ship satellite communication systems is to maintain constant communication quality.

Therefore, it is necessary to keep the antenna gain constant even if the ship shakes significantly.

Therefore, the entire antenna system had to be moved to keep the satellite always in front of the antenna.

In this case, it is often structurally advantageous to use different control axes for (i), which is a relatively slow change, and ([i) and G11], which are fast changes.

Therefore, the control stand is configured using three or four axes.

FIG. 1 shows the configuration of an antenna system in the case of a four-axis system.

1 is an antenna, 2 is an X axis, 3 is a Y axis, 4 is an EA axis, and 5 is an Az axis.

([i) and X] can be corrected by the X-Y axis, and (j) can be corrected by the El-Az axis.

However, due to the large number of axes, both the shape and weight become large.
Control motors and circuits are required for a total of four axes.

As a result, the cost of the antenna attitude control drive system has increased, accounting for 76% of the entire antenna system.

In a communication system that requires such an antenna system, it is impossible to significantly reduce the price of communication equipment.

However, there are many ships that desire to lower the cost of communication equipment, even if it means lowering the quality of communication in some cases.

For example, small and medium-sized fishing boats fall into this category.

In order to solve these problems, the present invention widens the antenna beam width when the ship is shaking significantly, such as during stormy weather.
As a result, the present invention provides a marine satellite communication system that simplifies and lowers the cost of the antenna control drive system by maintaining communication with reduced line quality.

The present invention will be described in detail below using the drawings.

FIG. 2 shows an example of the radiation pattern of the antenna used in this method.

The horizontal axis is the radiation angle θ of the antenna, which corresponds to the rocking angle of the ship.

The electric field strength f is plotted on the vertical axis.

In Fig. 2, 06 is the limit radiation angle that guarantees high quality communication by using the high gain beam 6, and θ7
is the limit radiation angle that guarantees poor quality communication using a low gain beam 7.

If the ship is not rocking much (θ<θ6), even if the antenna beam is made as sharp as 6, the received electric field will not drop significantly.

On the other hand, if the ship's rocking is large (θ〉θ6),
With beam 6, the received electric field is significantly reduced, but by widening the beam width as with beam 7, the main beam can capture the satellite even when the ship is shaking significantly.

In this case, by switching the antenna beam to 7, it is possible to completely omit the antenna control/drive system for correcting the ship's rocking (1i) and 011).

Instead, the antenna gain necessarily decreases because the frontal direction of the antenna beam is shifted away from the satellite.

For example, for antenna pattern 6, the minimum electric field to maintain high quality communication is f6(θ6), and for antenna pattern 7, the minimum electric field to maintain low quality communication is f'r(θ7). It is.

Here, f distinguishes the antenna pattern, and the subscript distinguishes the pattern.

Therefore, for example, if the ship is rocking heavily, pattern 6
Compared to the case where the maximum gain direction is always directed toward the satellite,
C/N deteriorates by f7(θ7)/f60.

FIG. 3 is a time chart regarding the temporal changes in the rocking of the ship and the switching of the antenna beam width.

Switching from beam 6 to beam 7 is performed at point 8 where the ship's rocking becomes 06 or more, and switching from beam 7 to beam 6 is also performed at point 8 where the ship's rocking becomes θ6 or less.

In FIG. 3, the fast changing component corresponds to rolling, and the period is about 9 SeC.

This method can sufficiently follow this change if the antenna uses a high-grade variable beam width method.

By switching the beam width as described above, it is possible to cope with a decrease in the electric field due to the rocking of the ship.

Therefore, the antenna control/drive system only needs to compensate for changes in the latitude and longitude of the ship.

This change is very gradual and is of low quality as a control system.

Therefore, the X-Y control axes corresponding to the above-mentioned ship movements (ii) and (iii) can be omitted, and only Az-El is sufficient.

Therefore, it can be expected that the price of the antenna system will be approximately halved.

Even if there are two or more antenna gain set points that serve as a reference for controlling the beam width, the basic system configuration and advantages remain the same.

Further, instead of discrete switching, continuous changes may be used.

In addition, in the above explanation, the shaking of the boat (11) and (11)
The case where the antenna control/drive system for controlling 1) is completely omitted has been described.

However, the antenna pattern switching control described above can also be applied when a system for controlling the ship's rocking (:[) and (iii) is provided.

In this case, "swinging of the boat" in FIG. 3 may be replaced with "swinging of the boat - control angle".

The variable beam width mechanism used in the present invention includes the "variable beam width antenna device", "variable beam width antenna", "horn-switchable variable beam width antenna", and "mode A "switchable variable beam width antenna", a "variable beam width antenna with movable feed point position", etc. can be used.

As explained above, the present invention can greatly simplify the antenna control drive system and reduce the cost by switching the beam width of the antenna and preventing a significant drop in the received electric field due to the shaking of the ship. It has the effect of

Therefore, the price of communication equipment for ships can be significantly reduced, and the system of the present invention can also be applied to small ships.

[Brief explanation of drawings]

Figure 1 is a configuration diagram of a ship station antenna system for a conventional ship satellite communication system, Figure 2 is a characteristic diagram showing an example of the radiation pattern of a variable beam width antenna, and Figure 3 is a diagram showing temporal changes in ship rocking and the antenna beam. It is a time chart showing width switching. 1... Antenna, 2... X-axis, 3... Y-axis, 4...
...El axis, 5...Az axis, 6...Antenna pattern at high gain, 7...Antenna pattern at low gain,
8... Switching point from beam 6 to beam 7, 9...
- Minimum electric field point to maintain poor quality communication.

Claims (1)

[Claims] 1. In communication lines between ships and the ground, or between ships, which are relayed by satellites, antennas installed on ships have a structure that allows the beam width to be changed, so that when the ship's rocking exceeds a predetermined value, A ship using a variable beam width antenna, characterized in that the beam width of the antenna is controlled to be widened, and the beam width is controlled to return to the original beam width when the shaking of the ship returns to a predetermined value. Satellite communication method.