JPH0514050A - Antenna system - Google Patents

Abstract

PURPOSE:To realize the antenna system having a high angle measuring accuracy with less effect by self weight deformation by installing a sub antenna to a side opposite to a radio wave radiation direction of a main antenna. CONSTITUTION:A sub antenna 2 is installed to a side opposite to a radio wave radiation direction of a main antenna 1. In this case, since a hole 11 is provided to a main reflecting mirror 3, though a beam shift is caused to the main antenna, a hole 12 of the same size is made to a position symmetrical to the position of the hole 11 with respect to the sub antenna, or only the hole 11 is formed and a frequency selecting mirror surface to reflect a radio wave of the main antenna and to transmit the radio wave of the sub antenna is provided to the position.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an antenna device for tracking a rocket or satellite.

[0002]

2. Description of the Related Art FIG. 3 shows, for example, Japanese Patent Laid-Open No. 63-10730.
FIG. 4 is a plan view showing a conventional antenna device disclosed in Japanese Patent Laid-Open No. 3 publication, in which 1 is a main antenna and 2 is a sub-antenna provided outside the main antenna 1 so as to have the same radiation direction as the main antenna 1. It is 2. The sub antenna 2 is an antenna having a directivity and a gain smaller than those of the main antenna 1.

Next, the operation will be described. Sub antenna 2
Since the beam width is wider than the beam of the main antenna 1, the secondary antenna 2 is used for tracking to adjust the direction of the main antenna 1 having the same radiation direction. This Japanese Patent Laid-Open No. 63-10730
As an antenna applied to digital radio communication, Japanese Patent Laid-Open No. 3 discloses an example in which the main antenna 1 is a parabolic antenna having a diameter of 3.6 m and the sub-antenna 2 is a parabolic antenna having a diameter of 30 cm.

[0004]

If the antenna device disclosed in the above publication is used, for example, as a rocket tracking radar, the main antenna 1 has a large diameter antenna having a diameter of about 5 to 20 m and a sub antenna because of the line design. 2 requires an antenna with a diameter of about 0.3 to 2 m.

Further, the main antenna 1 has an azimuth of 0 ° to 360 °.
Angle, elevation angle 0 ° ~ 90 ° It is necessary to track all sky driving,
When the sub-antenna 2 is provided outside the main antenna 1 as described above, there is a problem that the self-weight deformation becomes large when the elevation angle changes, and the angle measurement accuracy deteriorates.

That is, since an antenna used in a radar for tracking a rocket has a large aperture diameter and a narrow beam width, a sub-antenna with a small aperture diameter and a wide beam width is required for capturing. When installed close to the outside, there is a problem that the self-weight deformation becomes large when the elevation angle changes.

The present invention has been made in order to solve the above problems, in which a sub-antenna is installed in the main antenna and the deformation of the main antenna due to its own weight when the elevation angle changes is small, resulting in high angle measurement accuracy. It is intended to obtain an antenna device having

[0008]

In the antenna device according to the present invention, a sub-antenna used as a capture antenna is installed in the surface of the main antenna opposite to the radio wave radiation direction of the main reflector, and the sub-antenna is installed. In addition, a hole having the same size as the hole provided on the main reflecting mirror surface of the main antenna is provided at a position symmetrical with respect to the center on the main reflecting mirror.

Further, the frequency selective mirror surface is provided in the hole provided in the main reflecting mirror surface of the main antenna for installing the sub antenna.

[0010]

In the antenna device of the present invention, since the sub-antenna for capturing is installed in the surface of the main reflecting mirror of the main antenna on the side opposite to the radio wave emission direction, it is necessary to make a hole in the main reflecting mirror surface. The main antenna causes beam shift and gain reduction, but beam shift becomes a problem especially in rocket tracking radar. Therefore, by installing holes of the same size as the holes provided on the main reflecting mirror surface of the main antenna for installing the sub-antenna at symmetrical positions on the main reflecting mirror, the main antenna for installing the sub-antenna again. This problem is solved by providing a frequency selective mirror surface in the hole provided in the main reflective mirror surface.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows an antenna device according to a first embodiment of the present invention. In the figure, 1 is a main antenna, 1a is its horn, 2 is a capturing sub-antenna installed inside this main antenna 21, 2a is its horn, 3 is a main reflecting mirror of the main antenna, and 11 is a capturing sub-antenna. A hole 12 is provided on the main reflecting mirror 3 of the main antenna 1 for installation, and a hole 12 is provided on the main reflecting mirror 3 of the main antenna 1 at a position symmetrical to the hole 11 and of the same size.

Next, the operation and effect will be described. When the hole 11 is provided in the main reflecting mirror 3 of the main antenna 1, the main antenna 1 undergoes beam shift and gain reduction.

For example, when a 0.4 m diameter capturing sub-antenna is installed in a 7 m diameter main antenna and a 0.4 m diameter hole is provided at a radius of 2 m from the center of the main reflecting mirror, the frequency is 6 GHz. , Beam shift about 0.00
At 14 °, a gain decrease of about 0.03 dB (calculated value) occurs.

By the way, in the case of an antenna device applied to a radar for tracking a rocket, this beam shift causes a problem in that the angle measurement accuracy is deteriorated.

This beam shift occurs because an asymmetrical phase error is generated on the main reflecting mirror by providing a hole on the main reflecting mirror. However, if holes of the same size are provided at symmetrical positions on the main reflecting mirror, the asymmetry of the phase error is eliminated and the beam shift no longer occurs.

If the gain reduction in this case is calculated,
The value is about 0.06 dB, which is not a particular problem.

In the above embodiment, a hole of the same size is provided on the main reflecting mirror at a position point-symmetrical to the hole provided for installing the sub-antenna for capturing.
As in the second embodiment of the present invention shown in FIG. 2, the radio wave 22 of the main antenna 1 is reflected in the hole 11 provided for installing the sub-antenna 2 for capturing, and the radio wave 23 of the sub-antenna 2 for capturing is transmitted. Frequency selective mirror surface (FSR: Frequency Selective Re
a flector) 21 may be provided. In this case, it is not necessary to provide holes of the same size at symmetrical positions on the main reflecting mirror as in the above embodiment, the labor required for processing is small, and the deformation of the main reflecting mirror surface due to processing is minimized. The effect is that it can be suppressed.

[0018]

As described above, according to the antenna device of the present invention, the sub-antenna having the directivity and the gain smaller than that of the main antenna is installed inside the main antenna,
In addition, since the holes on the main reflecting mirror of the main antenna provided to install the sub antenna and the holes of the same size are provided at symmetrical positions on the main reflecting mirror, the capturing sub antenna is separated from the main antenna. Since it is cheaper than the case where it is installed and the influence of its own weight deformation is small, there is an effect that an antenna device with high angle measurement accuracy can be obtained.

Further, a sub-antenna having a directivity and a gain smaller than that of the main antenna is installed inside the main antenna, and a frequency is provided in a hole on the main reflecting mirror of the main antenna provided for installing the sub-antenna. Since the selective mirror surface is provided, it is only necessary to provide one hole in the main reflecting mirror of the main antenna, and the cost can be reduced as compared with the case where the capturing sub-antenna is installed separately from the main antenna. Since it is small, there is an effect that an antenna device with high angle measurement accuracy can be obtained.

[Brief description of drawings]

FIG. 1 is a sectional side view and a plan view showing an antenna device according to a first embodiment of the present invention.

FIG. 2 is a sectional side view showing an antenna device according to a second embodiment of the present invention.

FIG. 3 is a plan view showing a conventional antenna device.

[Explanation of symbols]

1 main antenna 2 sub-antenna 3 main reflecting mirror of main antenna 11 hole provided on the main reflecting mirror of the main antenna 12 hole provided on the main reflecting mirror of the main antenna at a position symmetrical to the hole 11 having the same size 21 Frequency Selective Mirror (FSR) 22 Radio wave from main antenna 23 Radio wave from sub antenna

Claims (2)

[Claims] 1. A sub-antenna having a directivity and a gain smaller than that of the main antenna is installed on the side opposite to the radio wave radiation direction of the main antenna having a large directivity, and the main antenna provided for installing the sub-antenna An antenna device comprising a hole on the main reflecting mirror and a hole of the same size provided at points symmetrical with respect to the center of the main reflecting mirror. 2. A sub-antenna having a directivity and a gain smaller than that of the main antenna is installed on the side opposite to the radio wave radiating direction of the main antenna having a large directivity, and the main antenna provided to install the sub-antenna. An antenna device characterized in that a frequency selective mirror surface is provided in a hole on a main reflecting mirror.