JPH09243728A - Spacecraft onboard radar device - Google Patents

Abstract

(57) Abstract: It is an object of the present invention to realize highly accurate radar performance acquisition and highly accurate observation data acquisition. SOLUTION: A plurality of phase shifters 211, 212, 213,
The first beam controller 27 that sets the phase shift amount of 21n so as to perform beam scanning substantially equal to the antenna beam width.
And a plurality of phase shifters 211, 212, 213, ..., 21n
A second beam controller 28 for setting the phase shift amount of the beam scanning so as to perform beam scanning at an interval narrower than the antenna beam width,
The first and second beam controllers 27 and 28 are configured to be selectively switched and set via the switch selection circuit 26.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a spacecraft-equipped radar device mounted on a spacecraft such as an artificial satellite and used for various observations such as weather observation.

[0002]

2. Description of the Related Art Recently, in the field of space development, a radar system of a phased array antenna type using a phased array antenna capable of electrically scanning an antenna beam is mounted on a spacecraft to observe a wide range of areas. Has been studied to do.

FIG. 4 shows a radar apparatus used in a ground environment, which includes a plurality of antenna elements 11 and 1.
The phase shifters 21, 22, 22 and 23 are connected to 2, 13, ..., 1n.
..., 2n are connected respectively. Then, the phase shifter 21
A transmitter 3 and a receiver 4 are connected to 22, 23, ..., 2n via a power distributor 5 and a circulator 6. The output end of the beam controller 7 is connected to the phase shifters 21, 22, 2, 23, ..., 2n, and the phase shift amount is determined by the beam controller 7.
It is set in accordance with the phase shift amount control signal from to control the phases of the transmission signal and the reception signal.

In the above structure, the transmission signal transmitted from the transmitter 3 passes through the circulator 6 and the power distributor 5
To the phase shifters 21 and 22 via the power distributor 6.
, 23, ..., 2n are distributed and supplied. Then, the phase shifters 21, 22, 22, 23, ..., 2n input and set the transmission signal to a predetermined phase shift, and the antenna elements 11, 12, 13, 13
Output to 1n. Antenna elements 11, 12, 13,
, 1n radiates the input transmission signal toward the observation target.

Then, the reflected waves of the transmission signal reflected by the observation target are received by the antenna elements 11, 12, 13, ..., 1n. These antenna elements 11, 12, 13, 13, ..., 1
The received signal received by n is the phase shifter 21 2, 22 2, 23,
.., 2n, controlled to a predetermined phase, and supplied to the power distributor 5. The power distributor 5 combines the input received signals and outputs the combined received signals to the receiver 4 via the circulator 6, where the observation data is acquired. At this time, the phase shifter 2
The phase shift amount of 1, 22, 22, 23, ..., 2n is controlled via the beam controller 7, and the electromagnetic waves transmitted and received are controlled to the phases required for beam scanning.

In such a radar apparatus, the ability called spatial resolution for discriminating two observation objects spatially separated from each other is determined according to the antenna beam width. On the other hand, this antenna beam width is difficult to identify if the reflected waves from two observation targets that are included in one antenna beam and that are present at equal intervals are received at the same time. Therefore, by setting the beam scanning interval to be substantially equal to the antenna beam width, it is possible to secure desired performance and realize highly reliable and highly accurate identification of observation data.

By the way, in such a radar device, in order to obtain highly accurate observation data, the radar performance such as the transmission power and the reception gain is measured by a measuring instrument or the like, and based on the radar performance. By calibrating the acquired observation data, highly accurate radar observation can be realized.

[0008] However, in the above-mentioned conventional radar device, when it is mounted on a spacecraft to observe the global environment and the like, a measuring instrument for measuring the radar performance is required due to the demand for weight reduction and the like required in the field of space development. However, it is difficult to directly use it because it is difficult to mount.

Therefore, for example, as shown in FIG. 5, a spacecraft 8 is equipped with a radar device 9, and a calibration receiver 10 is arranged on the ground surface on the flight path of the radar device 9 to provide the radar device. A method is conceivable in which the calibration receiver 10 directly receives the transmission signal from the calibration receiver 10 to measure the transmission power Pt of the radar device 9 based on the reception power Pr of the calibration receiver 10. There is.

That is, the received power P of the calibration receiver 10
Let r be the wavelength, r be the distance between the radar device 9 and the calibration receiver 10, be the antenna gain of the radar device 9 be Gt, and let the antenna gain of the calibration receiver 10 be Gr, then Pt = (λ / 4πr ) ² · Pr · Gt · Gr (1) Where λ, r, Gt and Gr
Is a known value, the transmission power P is calculated based on the equation (1).
t is calculated.

However, in the above measuring method,
For example, as shown in FIG. 6, if the antenna beams 91, 92, 93, ..., 9n from the radar device 9 are not accurately directed to the calibration receiver 10, the antenna gain Gt of the radar device 9 is known. Since it is different from the value, there is a problem that reliable and highly accurate measurement is difficult.

Further, the attitude of the spacecraft 8 is generally
Since the error of about 0.2 ° is included and the predicted orbit is also included, it is difficult to dispose the calibration receiver 10 substantially in the flight path of the spacecraft 8. is there.

For example, when the radar device 9 scans the antenna beams 91, 92, 93, ..., 9n as shown in FIG. 6, if the calibration receiver 10 exists at the Y position,
The positions B1, B2 of the antenna beams 91, 92, 93,
At B3, since the beam is shifted from the beam center, an error is included in the reception level of the receiver 10,
It becomes difficult to accurately calculate the reception level.

Further, the antenna beams 91, 92, 9
The reception levels of 3 ... 9n have the pattern characteristics as shown by the solid line in FIG. 7 when the change with time is measured, and each can be obtained in a functional form by, for example, the least square method. Therefore, when the pattern characteristic is obtained by this function form and interpolated, the reception level shown by the broken line in FIG. 7 is obtained, and the transmission power Pt can be obtained from this reception level.

However, in the above method of calculating the reception level, since the signal levels of the antenna beam 91, the antenna beam 92, and the antenna beam 93 have a level difference of several tens of dB or more, the measurement data of the reception level is the antenna beam 91, There is a possibility that a large error may occur depending on the antenna beam 92 and the antenna beam 93, it is difficult to interpolate with high accuracy, there is a problem that the reliability of measurement accuracy is poor, and highly accurate calibration is difficult. .

[0016]

As described above, the conventional radar apparatus has a problem that it is difficult to calibrate the observation data with high accuracy when the radar apparatus is mounted on a spacecraft. The present invention has been made in view of the above circumstances, and is a radar for mounting on a spacecraft that realizes acquisition of highly accurate radar performance with a simple configuration and is capable of acquiring highly accurate observation data. The purpose is to provide a device.

[0017]

The present invention is directed to a plurality of phase shifters for controlling the phases of electromagnetic waves transmitted and received by a plurality of antenna elements, and transmissions transmitted from a transmitter to the plurality of phase shifters. The signals are distributed and supplied, radiated into space through the plurality of antenna elements, and the reception signals received by the plurality of antenna elements supplied through the plurality of phase shifters are combined and supplied to a receiving unit. Power distribution means, first beam control means for setting a phase shift amount so that the plurality of phase shifters perform beam scanning substantially equal to the antenna beam width, and the plurality of phase shifters are narrower than the antenna beam width. Second beam control means for setting a phase shift amount so as to perform beam scanning at intervals,
A radar apparatus for mounting on a spacecraft is provided with a beam scanning selection means for selectively switching and controlling the first and second beam control means.

According to the above structure, the beam scanning selection means controls the switching between the first and second beam control means so that the beam scanning interval is substantially equal to the antenna beam width interval and the interval narrower than the antenna beam width interval. The phase shift amount is switched and controlled so as to have it. Therefore, by switching and setting the beam scanning having a substantially antenna beam width interval suitable for radar observation and the beam scanning having an interval narrower than the antenna beam width interval suitable for measurement of radar performance, highly accurate observation data Acquisition is realized, and highly accurate calibration of observation data is realized as much as possible without providing a radar performance measuring device.

[0019]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 shows a radar apparatus for mounting on a spacecraft according to an embodiment of the present invention, which comprises a plurality of antenna elements 201, 202, 203.
, ..., 20n are mounted on the spacecraft (see FIG. 5). Then, the plurality of antenna elements 201, 2
The phase shifters 211 and 212 are connected to 02, 203, ..., 20n.
, 213, ..., 21n are respectively connected. A transmitter 22 and a receiver 23 are connected to the plurality of phase shifters 211, 212, 213, ..., 21n via a power distributor 24 and a circulator 25. Then, the phase shifters 211, 212, 213, ..., 21n are connected to the first and second beam controllers 2 through the switching selection circuit 26.
7, 28 are respectively connected. For example, a command from the ground station is input to the switching selection circuit 26, and in response to this command, the first and second beam controllers 27 and 28 are received.
Is selectively controlled.

Of these, the first beam controller 27 stores phase data for performing beam scanning at a width interval substantially equal to the antenna beam width suitable for radar observation, and based on this phase data, the phase shifter 211, 21 2, 213, ..., 21
Control the amount of phase shift of n.

On the other hand, the second beam controller 28 stores phase data for performing beam scanning at an interval narrower than the antenna beam width suitable for acquiring radar performance such as transmission power Pt, for example, a width dimension of 1/2. , 21n based on this phase data are controlled.

In the above structure, during radar observation, the switching control circuit 26 is controlled by a command to switch to the first beam controller 27. Here, the first beam controller 27 causes the phase shifter 211, based on the phase data scanned with a beam scanning width substantially equal to the antenna beam width.
Set the phase shift amounts of 212, 213, ..., 21n. As a result, the transmission signal transmitted from the transmitter 22 is supplied to the power distributor 24 via the circulator 25, and the plurality of phase shifters 211, 212, 2 are supplied via the power distributor 24.
.., 21n are distributed and supplied. Phase shifters 211 and 2
, 21n set the supplied transmission signal to a predetermined phase, and the antenna elements 201, 202, 2
, 03, 20n. Here, the transmission signal is radiated toward the observation target via the antenna elements 201, 202, 203, ..., 20n.

When the transmission signal radiated toward the observation target is reflected by the observation target, the reflected wave is received by the antenna elements 201, 202, 203, ..., 20n. These antenna elements 201, 202, 203, ..., 2
The received signal received at 0n is the phase shifter 211, 212, 2
, 21n are controlled to a predetermined phase, and then guided to the power distributor 24 to be combined. Then, the received signal formed by the power distributor 24 is guided to the receiver 23 via the circulator 25, and the observation data is acquired there.

When observing data to be calibrated by obtaining the transmission power Pt, for example, the calibration receiver 10 shown in FIG. 5 is similarly arranged on the flight path of the spacecraft 8 on the ground surface. At the same time, the command from the ground is switched and selected circuit 2
6 and the operation of the switching selection circuit 26 is controlled. Here, the switching selection circuit 26 switches and sets the first beam controller 27 to the second beam controller 28.

Here, the second beam controller 28 shifts the phase shift amount based on the phase data scanned by the beam scanning width narrower than the antenna beam width, by the phase shifters 211, 212 and 2.
, ..., 21n to output the phase shifters 211, 212
, 213, ..., 21n are switched and set.

As a result, the transmission signal transmitted from the transmitter 22 passes through the circulator 25 and the power distributor 24.
To the phase shifters 211, 212, 213, ...,
21n and is set to a predetermined phase. And
The transmission signals whose phases are set by the phase shifters 211, 212, 213, ..., 21n are, as shown in FIG. 2, antenna elements 201, 202, 203 ,. Beams 301 and 302
, 303, ..., 30n for beam scanning. Then
These antenna beams 301, 302, 303, ..., 30
n is received by the calibration receiver 10 arranged on the ground surface (see FIG. 2), this received signal is guided to a not-shown arithmetic unit, and the time change of the signal level is calculated and based on the received level. Transmission power Pt is obtained.

That is, assuming that the calibration receiver 10 is arranged at the position A in the flight path shown in FIG. 2, the positions A1, A2, A3, A4 of the antenna beams 301, 302, 303, 304, 305 are arranged. , A5, and the time variation of the reception level is taken, the pattern shown by the solid line in FIG. 3 is obtained. When this is expressed by the above-mentioned functional form, the reception level shown by the broken line in FIG. 3 can be obtained.

At this time, at the position A3, the positions A1 and A
2 is received at a signal level within an angle corresponding to the beam scanning width and is received at a level lower than the positions A1 and A2 by several tens of dB. As a result, the reception level obtained by the functional form is interpolated as indicated by the broken line in FIG.
The t is calculated and the observation data is calibrated. Here, the reception level is such that the beam pointing direction is the calibration receiver 10.
The transmission power Pt can be calculated with high accuracy because the estimation can be performed at a level that is substantially the same as that of the direction.

As described above, the spacecraft-equipped radar device includes a plurality of phase shifters 211, 212, 213 ,.
A first beam controller 27 that sets a phase shift amount of 1n so as to perform beam scanning substantially equal to the antenna beam width, and a phase shift amount of a plurality of phase shifters 211, 212, 213, ..., 21n. A second beam controller 28 that is set to perform beam scanning at an interval narrower than the width is provided, and these first and second beam controllers 27 and 28 are selectively switched and set via a switch selection circuit 26. As configured.

According to this, switching control is performed by the first beam controller 27, the beam scanning interval is set to a substantially antenna beam width interval, observation data is acquired, and switching is performed by the second beam controller 28. By controlling and setting the beam scanning interval to be narrower than the antenna beam width interval, it is possible to acquire highly accurate observation data and to acquire highly accurate reception levels without the need for a radar performance measuring instrument as in the past. It is possible, and while ensuring miniaturization, highly accurate calibration of observation data is realized, and highly accurate radar observation is realized.

In the above embodiment, the calibration receiver 10 receives the received signal and outputs the antenna beam 301.
, 302, 303, ..., 30n based on the transmission power Pt
However, the present invention is not limited to this and is applicable to the case where a transmitter is arranged on the ground to measure the reception gain.

Further, in the above-mentioned embodiment, the case where the beam scanning width is narrower than the antenna beam width by 1/2 is described. However, the beam scanning width is not limited to this, and the beam scanning width is smaller than the antenna beam width. If the interval is narrow, it may be wider or narrower than the width of 1/2, and the narrower the interval, the more accurate the estimation of the reception level becomes possible, and the effective effect is expected.

Further, in the above embodiment, the case where the calibration receiver 10 is calibrated so as to be arranged on the ground surface has been described, but the present invention is not limited to this, and the calibration receiver 10 may be arranged, for example, at a space station or the like. May be.

Further, in the above-described embodiment, the case where the command for controlling the operation of the switching selection circuit 26 is configured to be transmitted from the ground has been described, but the present invention is not limited to this, and it is transmitted from, for example, a space station. It can also be configured as follows.

Therefore, it is needless to say that the present invention is not limited to the above-described embodiments, and various other embodiments can be configured without departing from the scope of the present invention.

[0036]

As described in detail above, according to the present invention, a spacecraft which is capable of acquiring highly accurate radar performance with a simple structure and acquiring highly accurate observation data. An on-board radar device can be provided.

[Brief description of drawings]

FIG. 1 is a diagram showing a radar device for mounting on a spacecraft according to an embodiment of the present invention.

2 is a diagram showing a beam scanning state of an antenna beam based on the second beam controller in FIG. 1. FIG.

FIG. 3 is a diagram showing a time change of a reception level of FIG.

FIG. 4 is a diagram showing a conventional radar device.

FIG. 5 is a view shown to explain the problem of FIG. 4;

FIG. 6 is a diagram showing a beam scanning state of the antenna beam of FIG.

FIG. 7 is a diagram showing a temporal change of a reception level based on the beam scanning of FIG.

[Explanation of symbols]

8 ... Spacecraft. 10 ... Receiver for calibration. 201, 202, 203, ..., 20n ... Antenna elements. 211, 212, 213, ..., 21n ... Phase shifters. 22 ... Transmitter. 23 ... Receiver. 24 ... Power distributor. 25 ... Circulator. 26 ... Switching selection circuit. 27 ... 1st beam controller. 28 ... A second beam controller. 30 1, 30 2, 30 3, ..., 30 n ... Antenna beam.

Claims (4)

[Claims] 1. A plurality of phase shifters for controlling the phases of electromagnetic waves transmitted and received by a plurality of antenna elements, and a plurality of phase shifters for distributing and supplying a transmission signal transmitted from a transmission unit to the plurality of phase shifters. Radiating into space through the antenna element of, and combining the received signals received by the plurality of antenna elements supplied through the plurality of phase shifters, and supplying the combined power to the receiving unit, First beam control means for setting a phase shift amount so that the phase shifter performs beam scanning substantially equal to the antenna beam width; and the plurality of phase shifters performing beam scanning at intervals narrower than the antenna beam width. A radar apparatus for mounting on a space vehicle, comprising: a second beam control means for setting a phase shift amount; and a beam scanning selection means for selectively switching and controlling the first and second beam control means. 2. The radar apparatus for mounting on a spacecraft according to claim 1, wherein the beam scanning selecting means is controlled in response to a command from the ground. 3. The radar apparatus for mounting on a spacecraft according to claim 1, wherein the beam scanning set by the second beam control means is set at an interval of 1/2 of the antenna beam width. . 4. The spacecraft on-board radar device according to claim 1, wherein the second beam control means is selected when measuring radar performance.