JP2513406B2 - Antenna device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an antenna device having a function of automatically tracking a satellite emitting a beacon wave by a self-tracking system.

[0002]

2. Description of the Related Art The self-tracking method is different from program tracking in that it receives a radio wave emitted by a target to detect a bearing error,
Although the aperture plane antenna is automatically directed in that direction, among the antenna devices having the function of automatically tracking by such a self-tracking system, the antenna device targeted by the present invention is an antenna beam of an aperture plane antenna that is deviated. It has a function of processing and detecting the azimuth information of the target based on the arrival radio wave and its change, and pointing the antenna in the direction of the target.

As this type of antenna device, a conical scan antenna, for example, is conventionally known. As shown in FIG. 4 (sub-reflector rotation type) and FIG. 5 (primary radiator rotation type), this conical scan antenna is set to be a sub-axis that is deviated from the antenna axis 12 of the reflection mirror 1 as an aperture antenna. The reflector 8 (FIG. 4) and the primary radiator 9 (FIG. 5) are connected to the motor 1
1, the antenna beam is mechanically rotated around the antenna axis 12 to rotate the antenna beam in a conical shape.

When the target is in the center of the antenna beam, the received electric field is constant, but when it is out of the target, the received electric field undergoes amplitude modulation. Since this modulation frequency is equal to the rotation frequency of the antenna beam, the direction in which the antenna beam deviates from the target can be understood from the relationship between the phase and the beam pointing direction.

[0005]

As described above, the conical scan antenna is of a type in which the sub-reflecting mirror of the Cassegrain antenna is slightly tilted for rotation (FIG. 4) or a primary radiator is rotated by bias feed. Although there is a type (FIG. 5) that causes them, there is a problem that it is necessary to pay attention to the wear of the rotating parts because they have mechanical rotating parts. Also, FIG.
However, in order to smoothly rotate the sub-reflecting mirror whose center of gravity greatly changes due to eccentricity, counterbalance is required, and the increase in weight makes it difficult to rotate at high speed.

The present invention has been made in view of such a problem, and an object thereof is to automatically shift a satellite by electrically displacing an antenna beam at a high speed with a simple structure without a mechanical rotating portion. An object is to provide an antenna device that can be tracked.

[0007]

In order to achieve the above object, the antenna device of the present invention has the following structure. That is, the antenna device of the present invention includes at least one reflecting mirror; four horns arranged around the antenna axis in the vicinity of the focal point of the reflecting mirror, and an equal phase provided at the base end portions of the four horns. .A primary radiator consisting of an equal amplitude power divider;
And the four horns are installed on the outer wall surface of each.
A resonator with a filter that is coupled to the horn through a coupling hole that is electrically coupled to an electric field excited inside the horn ; Is a band-pass filter that passes only the beacon wave emitted by the satellite, and the resonator performs an on / off operation to change its resonance frequency between the frequency of the beacon wave and other frequencies. An ON / OFF operation of the diode is provided .
One around the antenna axis or two adjacent pairs
Ante radiated from the primary radiator while sequentially switching
The nabeam is tilted from the antenna axis at a predetermined angle
It is characterized in that it is rotated in a conical shape around the axis .

[0008]

Next, the operation of the antenna device of the present invention having the above construction will be described. In the present invention, four primary radiators are used.
Use one with horns, provide resonators with a filter on each horn, and turn on / off the diode so that the resonance frequency of the resonator changes to the frequency of the beacon wave and other frequencies. There is.

For example, when one of the four resonators is caused to resonate with the beacon wave by turning on or off the diode, the impedance of the horn changes greatly and the combined amplitude distribution of the four horns changes. That is, the phase distribution of the primary radiator can be inclined at a certain angle, and the antenna beam can be displaced. This is
The same applies when two diodes adjacent to each other around the antenna axis are turned on or off as a set.

Therefore, one diode is turned on or off.
When switching one by one or two adjacent ones around the antenna axis as a set, the tilted phase distribution of the primary radiator changes into four states, and when it is irradiated on the reflecting mirror, it corresponds to each phase distribution. Antenna beams are formed that are directed in four different directions.

Since it is possible to switch the formation directions of the four antenna beams at a high speed, it is possible to form a beam equivalent to a conically rotating beam in the conventional conical scan method.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows an antenna device according to an embodiment of the present invention. Although the same reference numerals are used for the same names as those shown in FIGS. 4 and 5 for convenience, this antenna device receives the beacon wave emitted from the satellite in the vicinity of the reflector 1 and the focal point of the reflector 1. A primary radiator 9 arranged accordingly.

The primary radiator 9 includes four horns A, B, C and D symmetrically arranged around the antenna axis 12 and the four horns.
It is provided with a waveguide type 4 distributor 3 of equal phase and equal amplitude connected to the base end of each horn.

Each of the four horns is equipped with a resonator 2 with a filter, which is coupled to the horn through a coupling hole 4 on the outer wall surface thereof. The device 5 is a bandpass filter that passes only the beacon wave emitted by the satellite, and the resonator 6 includes a diode 7 that changes its resonance frequency between the frequency of the beacon wave and another frequency. The diode 7 is turned on / off by a controller (not shown).

Therefore, when, for example, one of the four resonators is caused to resonate with the beacon wave by turning the diode on or off, the impedance of the horn changes greatly.
Since the composite amplitude distribution of the individual horns changes, for example, in FIG.
The phase distribution of the primary radiator can be tilted at an angle as shown in FIG. 3, and the antenna beam can be displaced as shown in FIG.

FIG. 2 shows a radiation pattern of four horns, that is, the primary radiators, when only the resonator of the horn A is resonated with a beacon wave. In FIG. 2, the electric field strength on the cut surface obtained by cutting the pattern along the diagonal line of minus 45 degrees shown in the horn D is a broken line (a), the phase is a broken line (b), and the phase in the direction of angle 0 is flat and inclined. I haven't.

On the other hand, the electric field strength at the cut surface obtained by cutting the pattern along the diagonal line of the horn A of plus 45 degrees is a solid line (c), the phase is a solid line (d), and the phase in the direction of the angle 0 rises to the right. It becomes the characteristic that it inclines at a certain angle.

FIG. 3 shows an antenna pattern when the radio wave emitted from the primary radiator 9 is applied to the reflecting mirror 1. In FIG. 3, (e) is a pattern in which none of the four resonators resonates with the beacon wave, and the antenna beam is formed so as to be oriented in the direction of angle 0.

On the other hand, (f) is an antenna pattern when the reflection mirror 1 is irradiated with the pattern shown in FIG. 2, and the antenna beam is directed in the direction of approximately +1 degree deviated from the angle 0 to the plus side. Formed.

Therefore, when the diodes 7 which are turned on or off are sequentially switched one by one, the tilted phase distribution of the primary radiator 9 changes into four states, and when it is irradiated on the reflecting mirror 1, the respective phase distributions are irradiated. The antenna beams are formed in four different directions corresponding to.

Since it is possible to switch the formation directions of the four antenna beams at high speed, it can be understood that a beam equivalent to the conically rotating beam in the conventional conical scan system can be formed.

Since normal communication signals other than the beacon wave do not pass through the filter 5 and are not affected by the resonator 6, the four horns are excited with equal amplitude and phase.
Communication can be performed via the satellite line as usual.

In the above description, it is assumed that the diodes 7 are operated one by one, but the same effect can be obtained by operating two adjacent diodes around the antenna shaft 12 as one set in order. Further, although the reflecting mirror 1 shows one parabolic reflecting mirror, it is needless to say that the present invention can be similarly applied to any reflecting mirror that is normally used such as a plurality of reflecting mirrors.

[0024]

As described above, in the antenna device of the present invention, the one having four horns is used as the primary radiator, and each horn is provided with a resonator with a filter to turn on the diode. When the resonator is turned off, the resonance frequency of the resonator is changed between the frequency of the beacon wave emitted by the satellite and another frequency. Therefore, turn on or off one diode at a time or two adjacent diodes around the antenna axis. When switched in sequence as one set, the tilted phase distribution of the primary radiator changes into four states, and when it is irradiated on the reflecting mirror, antenna beams directed in four different directions corresponding to each phase distribution are formed. However, since switching of the formation directions of these four antenna beams can be performed at high speed, it is possible to use a conically rotating beam in the conventional conical scan method. There is an effect that can form a valence beam. Further, since it has no rotating part, the structure is simple, the size can be reduced, and the waveguide structure has an effect that it can be applied to high power.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of an antenna device according to an embodiment of the present invention.

FIG. 2 is a radiation pattern of a primary radiator when a resonator of a horn A resonates with a beacon wave.

FIG. 3 is an antenna pattern when a radio wave radiated from a primary radiator is applied to a reflecting mirror.

FIG. 4 is a schematic configuration diagram of a conventional conical scan antenna (sub-reflecting mirror type).

FIG. 5 is a schematic configuration diagram of a conventional conical scan antenna (primary radiator rotation type).

[Explanation of symbols]

 1 Reflector 2 Resonator with Filter 3 Waveguide 4 Distributor 4 Coupling Hole 5 Filter 6 Resonator 7 Diode 9 Primary Radiator 12 Antenna Axis A, B, C, D Horn

Claims (1)

(57) [Claims] 1. At least one reflecting mirror; four horns arranged around an antenna axis in the vicinity of the focal point of the reflecting mirror, and equal-phase and equal-amplitude powers provided at the base ends of the four horns. A primary radiator comprising a distributor, and the four horns are provided on the outer wall surfaces of the respective horns.
A resonator with a filter that is coupled to the horn through a coupling hole that is electrically coupled to an electric field to be excited inside ; and the resonator with the filter is only a beacon wave emitted from a satellite by the filter. A band-pass filter that passes through the resonator, the resonator including a diode that performs an on / off operation to change the resonance frequency between the frequency of the beacon wave and another frequency ;
1 ON / OFF operation of the diode around the antenna axis
While switching sequentially one by one or two adjacent two
The antenna beam radiated from the primary radiator is
Angled from the antenna axis and conical around the antenna axis
An antenna device characterized in that it can be rotated .