JPH0235802A - Antenna system for vessel - Google Patents

Abstract

PURPOSE:To attain the communication which is small, light-weight, of a low power, of a low cost and stable by having a mechanism in which an antenna fitting shaft can always make a shaped beam to receive an electric wave from an artificial satellite coincident to the earth central direction. CONSTITUTION:A shaped beam antenna 1 has a maximum sensitivity direction in an artificial satellite direction and a sensitivity width is provided so that an artificial satellite can be easily grasped and the directivity formed is given. The shaped beam antenna 1 is coupled with a gravity balance mechanism part 2, constitutes the antenna system and the antenna system is fitted at an antenna system fitting part 3. In the gravity balance mechanism part 2, even at the time of the oscillation due to the rolling, pitching and the like of a vessel loading the shaped beam antenna 1, the fitting shaft direction for the vessel of the shaped beam antenna 1 is always directed to the earth center. Thus, such a shaped beam pattern 7 can be formed by having a maximum antenna gain for an artificial satellite direction 103, having the characteristic of an effective sensitivity width set so as to be easily grasped, and for example, by setting the shape of the antenna.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a marine antenna system, and more particularly to a marine antenna system that is mounted on a small vessel and can receive radio waves from a stationary artificial satellite with high sensitivity.

[Conventional technology]

Conventionally, when receiving radio waves from artificial satellites, this type of marine antenna system has been equipped with an omnidirectional antenna directly on the vessel, or a directional antenna such as a parabolic antenna that is used in conjunction with an automatic tracking function. It was installed and operated on ships.

FIG. 4 is a typical antenna pattern diagram of a conventional omnidirectional antenna. The relationship between the omnidirectional antenna pattern 101 and the zenith direction 102 is as shown in FIG.
It shows that the artificial satellite direction 103 is, for example, in the direction of θ.

FIG. 5 is a typical antenna pattern diagram of a conventional directional antenna. The beam direction 105 having the maximum reception gain of the antenna pattern 104 is caused to be tracked by the artificial satellite using an automatic tracking function.

FIG. 6 is an external view of a conventional directional antenna having an automatic tracking function. A parabolic antenna 4 having a desired directivity pattern is mounted on an antenna mount 6 together with an antenna drive device 5, and is driven in conjunction with an automatic tracking device (not shown) to produce a directivity pattern as shown in FIG. The antenna driving device 5 is used to direct the antenna to the artificial satellite.

[Problem to be solved by the invention]

The above-described conventional marine antenna system has the following drawbacks when a vessel is equipped with an omnidirectional antenna.

(1) Since it is an omnidirectional antenna, multipath fading is large due to reflections from the sea surface, and communication may be lost.

(2) Since it is omnidirectional, the antenna gain is less than OdB, and on the other hand, there is a limit to the transmission output of an artificial satellite, so it is not suitable for receiving high-speed data.

(3) Since a completely omnidirectional antenna cannot be realized, the antenna gain may fluctuate due to rolling of the ship, etc., and communication may be lost.

Furthermore, when a directional antenna such as a parabolic antenna with an automatic tracking function is attached to a ship, there are the following drawbacks.

(1) An antenna system having an automatic tracking function has a complicated configuration and is expensive, making it difficult to equip a small vessel.

(2) Due to rolling of the ship, etc., it takes a long time to capture radio waves from the satellite before starting automatic tracking.

[Means to solve the problem]

The marine antenna system of the present invention is a marine antenna system that is installed on a ship and receives radio waves transmitted from an artificial satellite, and has reception directivity that has characteristics that make it easy to capture radio waves transmitted from an artificial satellite from the operational area of the ship. It is configured to include a shaped beam (5haped beam) antenna and a gravity balance mechanism that always orients the mounting direction of the shaped beam antenna to the ship toward the center of the earth based on gravity.

〔Example〕

Next, the present invention will be explained with reference to the drawings.

FIG. 1 is a block diagram schematically showing an embodiment of the marine antenna system of the present invention.

The embodiment schematically shown in FIG. 1 is a shaped beam antenna that has the maximum sensitivity direction in the direction of the artificial satellite and has a directivity that is formed by setting a range of degrees of intensity so that it is easy to capture the artificial satellite. 1. 2. Gravity balance mechanism unit that always directs the installation axis of the shaped beam antenna 1 to the ship toward the center of the earth even if the ship on which the shaped beam antenna 1 is mounted is shaken due to rolling, pitching, etc. The antenna system includes an antenna system mounting section 3 to which an antenna system combining a shaped antenna 1 and a gravity balance mechanism section 2 is attached.

FIG. 2 is an antenna pattern diagram of the shaped beam antenna of the embodiment shown in FIG.

As shown in FIG. 2, the antenna has the maximum gain in the direction 10B of the artificial satellite, and has the characteristics of the effective range of anger set so as to be easy to capture, for example, by setting the shape of the antenna. Thus, such a shaped beam pattern 7 can be realized.

FIG. 3 is an explanatory diagram showing the positional relationship between a point on the earth and an artificial satellite. When a ship is at point A on the sea surface of the earth 107 and a geostationary artificial satellite is at point B, the angle θ is defined between the axis from point A toward the center of the earth and the direction toward point B of the geostationary satellite.

Next, the operation of the ship/J private antenna system of the embodiment shown in FIG. 1 will be explained.

For example, if the ship equipped with this ship antenna system is a small ship sailing in the sea near Japan, and the east longitude is 14
When receiving weather data from a geostationary meteorological satellite located at 0 degrees, the satellite will be located in the direction of θ, approximately 40 degrees from the axis toward the center of the earth, as shown in Figure 2.
Still images etc. from weather satellites can be received with an antenna gain of about 6 to 10 dB.

Furthermore, although a ship moves in any direction, by installing an antenna having a shaped beam as shown in FIG. 2 on the ship, an antenna gain of about 6 to 10 dB can be secured. This significantly improves the effects of sea surface reflections compared to omnidirectional antennas.

The gravity balance mechanism section 2 includes a shaped beam antenna 1
The balance weight 21 is composed of a balance weight 21 as a weight that always directs the 1-inch axis toward the center of the earth, and a gimbal mechanism 22 that gives a three-dimensional degree of freedom to the movement of the balance weight toward the center of the earth.
The shaped beam antenna 1 is rotatably held at fulcrums A and B of a gimbal mechanism 22, and the shaped beam antenna is held free from the effects of roll, pitch, and other agitation of the ship on which it is mounted.

〔Effect of the invention〕

As explained above, the present invention has a mechanism that allows the antenna mounting axis of the shaped beam for receiving radio waves from the satellite to always align with the direction of the center of the earth, thereby directing the shaped beam toward the satellite. Since the antenna can always be oriented stably, the antenna gain is always constant and stable communication is possible.Also, because it is a shaped beam, the antenna gain is always stable, so compared to an omnidirectional antenna,
It improves the antenna gain by about 10 dB and significantly suppresses the effects of sea surface reflections compared to omnidirectional antennas.It is also smaller, lighter, lower power, and lower cost than antenna systems with automatic tracking functions. This system has the advantage that it can be easily installed on small vessels.

[Brief explanation of the drawing]

FIG. 1 is a block diagram schematically showing the ship antenna system of the present invention, FIG. 2 is an antenna pattern diagram of the shaped beam antenna of the embodiment shown in FIG. 1, and FIG. 3 is a diagram of the shaped beam antenna of the embodiment shown in FIG. Explanatory diagram of satellite radio wave reception by pattern,
Figure 4 is a typical antenna pattern diagram of a conventional omnidirectional antenna, Figure 5 is a typical antenna pattern diagram of a conventional directional antenna, and Figure 6 is an external appearance of a conventional directional antenna with an automatic tracking function. It is a diagram. DESCRIPTION OF SYMBOLS 1... Shaped beam antenna, 2... Gravity balance R side part, 3... Antenna mounting part, 4... Parabolic antenna, 5... Antenna drive device, 6... Antenna mounting 1 inch Base, 7... Shaped beam pattern.

Claims (1)

[Scope of Claims] In a ship antenna system mounted on a ship to receive radio waves transmitted from an artificial satellite, a shape that has a receiving directivity characteristic that makes it easy to capture radio waves transmitted from an artificial satellite from the operating area of the ship. 1. A marine antenna system comprising: a shaped beam antenna; and a gravity balance mechanism that always directs the shaped beam antenna toward the center of the earth based on gravity.