JPS6394702A - Antenna driver - Google Patents

Abstract

PURPOSE:To continuously trace an object flying any region by providing a traverse axis orthogonal to an El axis within the horizontal plane including the El axis to an antenna of the vertical/horizontal (AZ-El) mount and compensating a range not traced by the AZ axis through the turning of the traverse axis when the object reaches the vicinity of the zenith. CONSTITUTION:In Case of a satellite at an altitude of 900km circulating above the earth, a rotating speed of >=13 deg./sec is required for the AZ axis 2 to trace a rotating angle of up to 88 deg. of the E axis 3. Thus, in order to trace the range of the remaining rotating angle 88-90 deg. of the El axis 3, the rotating speed of the AZ axis 2 remains as it is and the rotating angle of 88-92 deg. is given to a traverse axis 34. Since the traverse axis 34 acts only in the vicinity of the zenith, the rotating range can be narrow (4 deg. in this example) and the X-Y mount is formed within the range together with the El axis, the tracing in the vicinity of the zenith is facilitated.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a directional antenna driving device for tracking the arrival direction of radio waves transmitted from a flying target.

[Conventional technology]

Typical structures for driving the antenna to point in any direction are the AZ-E 1 mount and the X-
There are two types of Y mount.

The configuration of the AZ-E 1 mount system is shown in Figure 5fal.

In the figure, 1 is a reflector forming the antenna aperture, 2
3 is a vertical axis (hereinafter referred to as the AZ axis), and 3 is a horizontal axis (hereinafter referred to as the II axis) perpendicular to the AZ axis 2. Antenna rotation angle around AZ axis 2 from 0 to 360 degrees.

If the antenna is driven so that the antenna rotation angle about the EA axis 3 can be from 0 to 90 degrees, it becomes possible to direct the antenna in any direction by combining the rotation angles of both axes.

However, as shown in Fig. 6, if the amount of angular change in the flight path of the target is Δe on the vertical plane containing the target and Δa on the plane containing the target orthogonal to the vertical plane, then the AZ axis 2 and the EA axis 3
The antenna rotation angles are the original angles AZ and EI, respectively.
l, the rotation angle according to the angle change of the target object is ΔAZ, Δ
If E1, ΔAZ-Δa / cosE 1 - f
l) ΔE=Δe...It is expressed as (2). Therefore, in order to direct the direction of incoming radio waves from a target flying near the zenith, the rotational speed of the AZ axis 2 needs to be higher than the flight angular velocity of the target, 63.
At the zenith, it becomes bedless and untraceable.

On the other hand, the configuration of the X-Y mount system is shown in FIG. 5 (bl).

In the figure, 1 is a reflector forming the antenna aperture, 2
2.23 are horizontal axes (referred to as the X axis and Y axis, respectively) that are orthogonal to each other. Both around X axis 22 and Y axis 23 are 0.
If the antenna is driven to obtain a rotation angle of 180° to 180°, directing in any direction is possible by combining the rotation angles of both axes.

In this case, high-speed rotation is required for the target flying near the extension line direction of the If so, it can be tracked.

FIG. 7 shows the configuration of an antenna driving device in an AZ-E/X-Y mount. Reference numerals 11 and 12 indicate motors for driving the AZ axis or the X axis, and for driving the Ef axis or the Y axis, respectively. Reference numerals 13 and 14 denote power amplifiers for driving the motor as required in accordance with the automatic tracking error of each axis commanded from the outside.

[Problem that the invention seeks to solve]

As is clear from the above, when it is necessary to track a target passing near the zenith, the x-y mount method should be used. However, this X-Y mounting method
Unlike the Z-E ffi mount, where the center of gravity of the entire antenna is constant with respect to the rotation of the AZ axis and moves only with the rotation of the EA axis, it is The center of gravity also shifts. Therefore, the structure becomes complicated in adjusting the overall balance, and the weight increases.

This invention was made in order to eliminate the above-mentioned drawbacks, and AZ-E I! The object of the present invention is to provide an antenna driving device that is based on a mounting method and can track even near the zenith.

[Means for solving problems]

The antenna drive device according to the present invention provides an AZ-En mount antenna with a traverse axis perpendicular to the EA axis in a horizontal plane including the EA axis, and when the target reaches near the zenith, it cannot follow the AZ axis. The range is assisted by the rotation of this traverse axis.

For example, in the case of a satellite orbiting the earth at an altitude of 900 km, the EI
It is calculated that in order to track the l-axis rotation angle up to 88 degrees, the rotation speed of the ^Z-axis is required to be 13 degrees/sec or more. Therefore, in order to track the remaining rotational angle range of 88° to 90° of the Ef axis, the rotational speed of the AZ axis remains unchanged and the rotational angle of the traverse axis is set to 88° to 92°.

[Effect]

In this invention, since the traverse axis acts only near the zenith, its rotation range may be narrow (4 degrees in the above example), and within that range, along with the EA axis,
Since a Y mount is formed, tracking near the zenith is easily possible.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

In Fig. 2, reference numeral 1 indicates a reflector forming the antenna aperture, 2 indicates the AZ axis as the first rotation axis, 3 indicates the εβ axis as the second rotation axis, and 34 indicates the alignment of the reflector 1 with the εβ axis 3. This is a traverse axis as a third rotation axis for rotating around an orthogonal horizontal axis.

Further, FIG. 3 shows the state of rotation of the axis of the antenna when viewed from the zenith with respect to a target passing near the zenith. 41 is the antenna center position, 42 is the target position, and 53 is the flight path of the target.

FIG. 1 shows the configuration of a driving device for driving such an antenna. In the figure, 11°12.37 is the AZ axis 2. Ef axis 3. This is a motor for driving the traverse shaft 34. 38 is the rotation speed of AZ axis 2
output device, 39.40 are each El axis 3. A rotation angle detector 13° 14.43 of the traverse shaft 34 is a power amplifier for driving each motor 11, 12, 37 according to a required external command angle. 44 is a comparator that detects when the AZ-axis rotation speed has reached the maximum while driving both AZ-E6 axes, and 45 is the En-axis 3. Follow-up angle error detectors 46 to 48 calculate the follow-up angle error ΔAZ of the AZ axis 2 according to a calculation formula described later based on the rotation angle obtained from each rotation angle detector 39 and 40 of the traverse shaft 34. AZ-E j! Axial drive, AZ-En-) Switcher for switching the input of the power amplifiers 13, 14, 43 by Lahas axis drive, 49
is a comparator that detects whether ΔAZ calculated by the error detector 45 is 0° or not.

Here, when the AZ-axis speed reaches the maximum in the comparator 44, the switchers 46 to 48 shift from the state of ■ to the state of ■. After this, when ΔAZ=O° in the comparator 49, it indicates that the state shifts from the state ① to the state ②.

Next, the operation will be explained.

In FIG. 3, the antenna is currently in a state of automatic tracking of the target by driving both the AZ axis 2 and the El axis 3 so that the antenna beam center is directed in the direction of radio waves arriving from the target. The target has reached near the zenith, and the rudder shaft 2 has entered an area where it cannot track the target.
It is assumed that the traverse shaft 34 is not driven. At this time, FIG. 3 shows that there is a ΔAZOAZ-axis tracking angle error and a tracking angle error.

To determine whether the rotational speed of the AZ-axis 2 is no longer able to track the target object, the rotational speed of the AZ-axis 2 is detected by, for example, a tachometer generator 38 attached to the AZ-axis 2, and this is determined as the maximum possible rotational speed of the AZ-axis 2. Comparator 4
This can be easily determined by comparing 4.

When the rotation speed of AZ axis 2 reaches the maximum, AZ axis 2 and E7
! The terminals of the switchers 46 to 48 are switched from (1) to (2) E so that target tracking is performed by driving both the shaft 3 and the traverse shaft 34.

The Eβ axis 3 and the traverse axis 34 form a so-called X-Y mount, and in the state shown in FIG. ) If the rotation angle of the traverse shaft 34 by the mount is X and the rotation angle of the El axis 3 is Y, then it is expressed as follows. Therefore, it becomes. In other words, originally, the El axis 30 rotation angle when tracking with the AZ-E n mount changes continuously even if ΔAZ occurs, as shown in equation (4).
On the other hand, it can be seen that the traverse axis continuously changes from its original state of 90° to the rotation angle shown by equation (3). From this, the state in which the AZ axis 2 cannot be followed in FIG. 3 is as follows.
E7! Tracking is possible by driving both the shaft 3 and the traverse shaft 34, and automatic tracking of the target object can be maintained continuously.

However, the target object moves out of the vicinity of the zenith and returns to the original AZ axis and E/
To return to axis drive, move AZ axis 2 to EI! Angle detector 39.4 attached to each axis of axis 3 and traverse axis 34
It is necessary to drive at the maximum speed so that ΔAZ calculated by the follow-up angle error detector 45 based on equation (5) from both rotation angles Y and X detected from 0 becomes 0°. When the target object leaves the vicinity of the zenith, ΔAZ gradually becomes smaller, and finally the AZ axis 2 becomes able to follow it. At this point, the target object can be tracked by driving both the AZ axis 2 and the Eff axis 3, so ΔAZ=O° is detected by the comparator 49, and the switching devices 46 to 48 are automatically activated by the AZ-En mount. Switch to the tracking side (■ side). At this time +31. (If ΔAZ-〇 ° in formula 41, then X-90°, Y= E
ff, the traverse axis 34 returns to its original state, and E
It can be seen that the l-axis is equal to the rotation angle of the En-axis in the AZ-El mount.

The flow of the above operations can be summarized as shown in FIG. 4.

In the case of such a driving method, if the AZ and EA angles of the target object including the vicinity of the zenith are expressed as AZT and E1, respectively, it can be expressed by the following equation.

AZT - AZ + ΔAZ Here, AZ is the rotation angle of the AZ axis 2, Y is the rotation angle of the Ef axis 3, and ΔAZ is calculated from the rotation angle of the traverse axis 34 and the EIl axis 3 when the traverse axis is driven. A
This is the tracking angle error of Z-axis 2.

By the way, as an antenna drive device made using the same operating principle as the present invention, there is
There is a device described in Japanese Patent No. 4505.

This device targets a reflective parabolic antenna, and the sub-reflector is rotated in a horizontal plane perpendicular to the EIl axis, with the traverse axis as the third axis (by rotating the sub-reflector, the beam direction of the main reflector can be changed). (It takes advantage of the fact that it can rotate isometrically in the same direction). In this case, since the sub-reflector itself is generally lighter than the main reflector, it has the advantage of being easier to drive. However, in this conventional device, the range in which the rotation of the sub-reflector is equivalent to the rotation of the main reflector in the beam direction is about the beam width of the main reflector, for example 2.
A parabola with an aperture diameter of 10 m in the GHz band has a driving range of only about 1°. Therefore, a large-diameter parabola in a higher frequency band has a limited tracking range near the zenith, and cannot be applied if the flying speed of the target becomes high.

On the other hand, in the device of this embodiment, the drive range of the traverse axis can be set arbitrarily, so the tracking range is not limited, even in high frequency bands, large apertures, and even when the target is flying at high speed. Tracking becomes possible.

〔Effect of the invention〕

As described above, according to the present invention, in an antenna configuration based on a lightweight AZ-EI2 mount, the zenith can be reached by adding a traverse axis with a small drive range orthogonal to the AZT2 axis and the E/axis. It is possible to continuously track a target flying in any area including
It has the effect of being lightweight similar to the EJ mount, and is very effective when applied to zenith tracking antennas with strict weight restrictions.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram of an antenna driving device according to an embodiment of the present invention, and FIG. 2 is an AZ-E7! -) A diagram showing the configuration of the rubber mount, FIG. 3 is a diagram showing the axis rotation state of the antenna with respect to a target passing near the zenith in an embodiment of the present invention, and FIG. 4 is an antenna according to an embodiment of the present invention. A diagram showing the drive sequence, Fig. 5 (al is the conventional AZ-E
A diagram showing the configuration of the Il mount, FIG. 5(b) is a diagram showing the configuration of the conventional X
- A diagram showing the configuration of the Y mount, FIG. 6 is AZ, EI! in FIG. 5 ta+! FIG. 7 is a schematic diagram of a conventional antenna driving device. 2...First rotation axis (AZ axis), third axis of rotation (2nd rotation axis)
El axis), 34... third rotation axis (traverse axis),
38... Rotation speed detector, 44... Comparator, 39.
40...Rotation angle detector, 45...Following angle error detector, 49...Following angle error comparator, 46-48...
- Drive input switch for the 1st and 2nd and 3rd rotating shafts. Note that the same reference numerals in the figures indicate the same or equivalent parts.

Claims (1)

[Claims] (1) A first rotating shaft provided in the vertical direction, a second rotating shaft in the horizontal direction provided orthogonally to the first rotating shaft, and the first rotating shaft and the second rotating shaft. an antenna drive device that drives an antenna by having a third rotation axis provided orthogonally to both axes of the first rotation axis, the rotation speed detector detecting the driving speed of the first rotation axis; 2. A rotation angle detector for detecting the rotation angle of each of the third rotation axes, and determining the following angle error of the first rotation axis from the rotation angles of the second and third rotation axes detected by the detectors. a follow-up angle error calculator for calculating the following angle error; When the follow-up angle error detector detects that there is no follow-up angle error, the drive is switched from the drive by the second and third rotation axes to the first and second rotation axes. An antenna drive device characterized by comprising: switching means for switching to drive by a rotating shaft of the antenna.