JP3292024B2 - Synthetic aperture radar test equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a test apparatus for a synthetic aperture radar, which is a kind of radar for acquiring a microwave image of the earth's surface from a satellite or an aircraft.

[0002]

2. Description of the Related Art FIG. 11 shows, for example, "Results of Point Image Response Test for Synthetic Aperture Radar Research Model" (11th Remote Sensing Symposium hosted by the Society of Instrument and Control Engineers, Oct. 30, 31 1985). 1 shows a conventional synthetic aperture radar test apparatus shown in FIG. 1, in which 1 is a synthetic aperture radar as a device under test, and 2 is a primary radiation for transmitting and receiving radio waves to and from the synthetic aperture radar 1. , 3 is a transmission / reception switch for switching between transmission and reception in the primary radiator 2, 4 is a phase shifter for changing the phase shift of the reception signal from the transmission / reception switch 3 for each pulse, and 5 is the phase shifter An attenuator 4 for attenuating the output signal from the attenuator 4 is an amplifier for amplifying the output signal from the attenuator 5 and transmitting a radio wave to the synthetic aperture radar 1 via the transmission / reception switch 3 and the primary radiator 2.

Next, the operation will be described. Synthetic aperture radar is to temporally synthesize an equivalent array using the motion of an aircraft or a satellite as a radar platform. FIG. 12 is a diagram illustrating the principle of a synthetic aperture radar. In the figure, 1 is a synthetic aperture radar, 13
Is a radar beam and 14 is the ground surface. As shown in the figure, the synthetic aperture radar 1 moves from the position B to the position C while the ground surface 1 moves.
4 and continue to irradiate point A. Therefore, by synthesizing the data received from point B to point C,
An opening having a large C can be synthesized. At this time,
The length BC is referred to as a synthetic aperture length, and the time required to move the length BC is referred to as a synthetic aperture time. Thus, the synthetic aperture radar can obtain a high resolution that cannot be obtained by a normal radar system in the same direction as the traveling direction of the platform. However, in order to obtain this high resolution, it is necessary to correct the change in the distance between each receiving point and the observation point with respect to the received signal, and it is necessary to provide a signal processing circuit for this. Because this processing circuit is often large, it is often installed on the ground rather than on a platform. Note that the position correction processing in this signal processing circuit is hereinafter referred to as synthetic aperture processing. In the synthetic aperture radar described above, as can be seen from FIG. 12, the theoretical resolution is improved when the antenna length is shortened because the synthetic aperture length increases when the beam width is widened. In principle, the resolution is の of the antenna length. In the synthetic aperture radar, the resolution in the direction perpendicular to the platform is increased by a pulse compression technique used in a normal radar.

In order to test the entire system of the synthetic aperture radar having such a principle, a method of confirming a point image response using a target generator is used. This method is sufficiently far field for the synthetic aperture radar 1.
The test is performed by receiving a radio wave from the synthetic aperture radar at a far position that can be regarded as a target, placing a target generator that returns the radio wave after performing desired processing, and transmitting and transmitting the radio wave in space. Synthetic aperture radar 1
Radio wave transmitted from the primary radiator 2 of the target generator
, The phase shift value is changed by the phase shifter 4 via the transmission / reception switch 3, and the amplitude value is changed by the attenuator 5,
After being amplified by the amplifier 6, it is transmitted again from the primary radiator 2 to the synthetic aperture radar 1 via the duplexer 3. At this time, the phase shift of the phase shifter 4 and the amount of attenuation in the attenuator 5 are determined by the distance between the satellite or the aircraft and a certain point on the ground so that the synthetic aperture radar 1 flies and receives radio waves. The same as the history of In other words, the target signal from one point received during flight is simulated by changing the phase shift value and the attenuation value for each pulse with time as shown in FIG. FIG. 13 shows the time characteristic of the phase shift and the amount of attenuation set in the phase shifter 4 and the attenuator 5, where 15 is time, 16 is the amount of phase shift, and 17 is the amount of attenuation. As can be seen from FIG. 13, the distance between the target and the synthetic aperture radar 1 becomes the minimum distance when it approaches once and is right beside, and then moves away again. The radio wave transmitted from the synthetic aperture radar 1 is transmitted again by the primary radiator 2 after being subjected to the processing described above. This radio wave is received by the synthetic aperture radar 1 and subjected to the synthetic aperture processing to evaluate the point image response of the entire system.

[0005]

The conventional synthetic aperture radar test apparatus is configured as described above, and requires a large space for performing the test. For example, in the case of L band radar, a distance of several km or more is required. In addition, since it is necessary to perform the test outdoors, there is a problem that disturbance is mixed and accurate measurement cannot be performed.

Further, the conventional synthetic aperture radar test apparatus has a problem that only a test at a fixed radar beam angle can be realized.

Furthermore, the conventional synthetic aperture radar test apparatus has a problem that only a test with a single polarization can be realized.

Further, the conventional synthetic aperture radar test apparatus has a problem that only a test at a single frequency can be realized.

Further, in a conventional synthetic aperture radar test apparatus, a scan SAR (Synthetic Aperture) for scanning a beam at a high speed in order to widen an observation width.
Radar (Synthetic Aperture Radar) mode has a problem that the test cannot be realized. That is, in the scan SAR mode, since the beam position is changed at a high speed, there is a problem that a conventional synthetic aperture radar test apparatus that can cover only one beam position with a single set of antennas cannot be used.

Further, the conventional synthetic aperture radar test apparatus has a problem that the evaluation can be performed with only one target.

Further, the conventional synthetic aperture radar test apparatus has a problem that the function as an active radar calibrator as an external calibration source cannot be realized.

The present invention has been made to solve such a problem, and has as its object to realize a stable test without requiring a large space. It is another object of the present invention to cope with a variable off-nadir angle, a plurality of polarizations, a plurality of frequencies, a scan SAR mode, a plurality of targets, and an active radar calibrator.

[0013]

A test apparatus for a synthetic aperture radar according to a first aspect of the present invention includes a Near Field and a Far Field.
A metal surface offset parabola for performing a field conversion is provided.

[0014] Further, the synthetic aperture radar test apparatus according to the second invention comprises a Near Field and a Far Field.
A mesh surface offset parabola for performing d conversion is provided.

Further, in the synthetic aperture radar test apparatus according to the third invention, an antenna turntable for changing the elevation angle of the synthetic aperture radar in the synthetic aperture radar test apparatus according to the first invention is provided. It is a thing.

A test apparatus for a synthetic aperture radar according to a fourth aspect of the present invention is a polarization splitter for splitting polarized waves into a test apparatus for a synthetic aperture radar according to the first aspect of the present invention, and processes each polarization. And two types of phase shifters, attenuators, and amplifiers.

Further, a synthetic aperture radar test apparatus according to the fifth aspect of the present invention includes a duplexer for dividing a frequency into the synthetic aperture radar test apparatus according to the first aspect of the present invention, and a duplexer for processing each frequency. A phase shifter, an attenuator, and an amplifier are provided.

A test apparatus for a synthetic aperture radar according to a sixth aspect of the present invention includes a duplexer for splitting a frequency and a two-type polarization splitter for dividing the frequency into a test apparatus for a synthetic aperture radar according to the first aspect of the invention. 4 for processing frequency and polarization signals
A phase shifter, an attenuator, and an amplifier are provided.

Further, the synthetic aperture radar test apparatus according to the seventh aspect of the present invention includes a primary radiator, a phase shifter, a primary radiator, a phase shifter, and the like so that data at three different angles can be obtained. Two sets of attenuators and amplifiers are provided.

The test apparatus for a synthetic aperture radar according to the eighth aspect of the present invention can cope with a plurality of polarized waves at the same time.
A polarization splitter for splitting polarization and a polarization switch are provided in the synthetic aperture radar test apparatus according to the invention.

A test apparatus for a synthetic aperture radar according to a ninth aspect of the present invention is the test apparatus for a synthetic aperture radar according to the first aspect of the present invention, comprising: a delay line for delaying a signal so that two types of target signals can be generated; 2 types of phase shifter, attenuator,
And a directional coupler.

The synthetic aperture radar test apparatus according to the tenth aspect of the present invention is obtained by removing the metal surface offset parabola from the synthetic aperture radar test apparatus according to the ninth aspect.

[0023]

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiment 1 FIG. FIG. 1 is a view showing a first embodiment of the present invention. In FIG. 1, reference numeral 1 denotes a synthetic aperture radar, which is a device under test, and 2 denotes a primary radiator for transmitting and receiving radio waves to and from the synthetic aperture radar 1. 3, a transmission / reception switch for switching between transmission and reception in the primary radiator 2; 4, a phase shifter for changing the phase shift of the reception signal from the transmission / reception switch 3 for each pulse; An attenuator for attenuating the output signal from the attenuator; amplifying the output signal from the attenuator;
The amplifier 7 transmits a radio wave to the synthetic aperture radar 1 from the near field to the far field.
It is a metal surface offset parabola for converting to Field. Among the above, the synthetic aperture radar 1, the primary radiator 2, the transmission / reception switch 3, the phase shifter 4, the attenuator 5, and the amplifier 6 are equivalent to those of a conventional synthetic aperture radar test apparatus.

Next, the operation will be described. In the synthetic aperture radar testing apparatus configured as described above, the input / output of the synthetic aperture radar 1 is equivalently Far Field by the metal surface offset parabola 7 disposed between the synthetic aperture radar 1 and the primary radiator 2. . This is primary radiator 2
Is arranged at the focal position of the metal surface offset parabola 7, so that the radio wave from the primary radiator 2 toward the metal surface offset parabola 7 is reflected by the metal surface offset parabola 7 and then parallel radio waves as in the case of the lens in optics. And heads for the synthetic aperture radar 1. Conversely, the path from the synthetic aperture radar 1 to the primary radiator 2 is the same. Therefore, the devices after the primary radiator 2 are Near F
Despite being installed in the field, it becomes a parallel radio wave for the synthetic aperture radar 1, which is the test object,
An environment equivalent to Field can be realized. By converting into a Far Field in this way, the distance between the synthetic aperture radar 1 and the primary radiator 2 can be reduced from several km or more to several tens of meters in the related art, so that the radio wave condition in an anechoic chamber or the like is controlled. It is possible to perform accurate radar measurement in a room. The radio wave transmitted from the synthetic aperture radar 1 is Ne by the metal surface offset parabola 7.
After the ar Field radio waves have been converted to Far Field, they are received at the primary radiator 2 of the target generator located at the focal point of the parabola. This radio wave passes through the transmission / reception switch 3 in the same manner as the conventional synthetic aperture radar test apparatus, and then the phase shifter 4 changes the phase shift value, the attenuator 5 changes the amplitude value, and the amplifier 6 amplifies the radio wave. It is transmitted from the primary radiator 2 again to the metal surface offset parabola 7 via the transmission / reception switch 3. At this time, the phase shift of the phase shifter 4 and the amount of attenuation in the attenuator 5 are determined by the satellite in the same manner as in the case of the conventional synthetic aperture radar 1 so that the synthetic aperture radar 1 flies and receives radio waves. Alternatively, it is the same as the history of the distance between the aircraft and one point on the ground. In other words, the target signal from one point received during flight is simulated by changing the phase shift value and the attenuation value for each pulse with time as shown in FIG. This radio wave is again Fa by the metal surface offset parabola 7.
After being converted into rField, received by the synthetic aperture radar 1, and subjected to the synthetic aperture processing, the point image response of the entire system is evaluated.

Embodiment 2 FIG. 2 is a view showing a second embodiment of the present invention. In the figure, reference numeral 1 denotes a synthetic aperture radar as a device under test, and 2 denotes a primary radiator for transmitting and receiving radio waves to and from the synthetic aperture radar 1. 3 is the primary radiator 2
, A transmission / reception switch 4 for switching between transmission and reception, 4 is a phase shifter for changing the phase shift of the received signal from the transmission / reception switch 3 for each pulse, and 5 is an attenuation for attenuating the output signal from the phase shifter 4. The amplifier 6 amplifies the output signal from the attenuator 5 and transmits an electric wave to the synthetic aperture radar 1 via the transmission / reception switch 3 and the primary radiator 2. Near Field for radio waves
This is a mesh plane offset parabola for converting from to Far Field. Among the above, the synthetic aperture radar 1, the primary radiator 2, the transmission / reception switch 3, the phase shifter 4, the attenuator 5, and the amplifier 6 are equivalent to those of a conventional synthetic aperture radar test apparatus.

Next, the operation will be described. The synthetic aperture radar test apparatus configured as described above replaces the metal surface offset parabola 7 in the first embodiment with a mesh surface offset parabola 8, and the operation is the same as in the first embodiment. Mesh surface offset parabola 8
Has many small holes in the metal surface, and can have exactly the same function as the metal surface offset parabola 7 if the hole diameter is smaller than a certain size. Since the amount of metal constituting the offset parabola is reduced by the amount of the holes, it is possible to realize weight reduction.

Embodiment 3 FIG. 3 is a view showing a third embodiment of the present invention. In the figure, reference numeral 1 denotes a synthetic aperture radar as a device under test, and 2 denotes a primary radiator for transmitting and receiving radio waves to and from the synthetic aperture radar 1. 3 is the primary radiator 2
, A transmission / reception switch 4 for switching between transmission and reception, 4 is a phase shifter for changing the phase shift of the received signal from the transmission / reception switch 3 for each pulse, and 5 is an attenuation for attenuating the output signal from the phase shifter 4. The amplifier 6 amplifies the output signal from the attenuator 5 and transmits an electric wave to the synthetic aperture radar 1 via the transmission / reception switch 3 and the primary radiator 2, and the input / output 7 to the synthetic aperture radar 1. Near Field for radio waves
Reference numeral 9 denotes a metal-surface offset parabola for converting the data into a Far Field, and an antenna turntable 9 capable of changing the angle of the synthetic aperture radar 1 in the elevation direction. Of the above, synthetic aperture radar 1, primary radiator 2,
The transmission / reception switch 3, the phase shifter 4, the attenuator 5, and the amplifier 6 are equivalent to the conventional synthetic aperture radar test apparatus.

Next, the operation will be described. The synthetic aperture radar test apparatus configured as described above is different from the first embodiment in that an antenna turntable 9 for changing the angle of the synthetic aperture radar 1 in the elevation direction is added. This is for performing a system test of the synthetic aperture radar 1 with the beam scanning performed in the elevation direction. The antenna rotating table 9 is inverted by the elevation angle at which the synthetic aperture radar 1 performs the beam scanning. By rotating in the elevation direction and rotating the synthetic aperture radar 1 in the reverse direction, the beam eventually propagates horizontally. The operation other than performing such correction is the same as in the first embodiment.
Is the same as

Embodiment 4 FIG. 4 shows a fourth embodiment of the present invention. In the figure, reference numeral 1 denotes a synthetic aperture radar, which is a device under test, and 2 denotes a primary radiator for transmitting and receiving radio waves to and from the synthetic aperture radar 1. 3 is the primary radiator 2
, A transmission / reception switch for switching between transmission and reception, 10 a polarization splitter for distributing the input / output signal of the transmission / reception switch 3 for each polarization, and 4 a for each pulse with respect to the horizontal polarization reception signal from the polarization splitter 10. A first phase shifter 5a for changing the phase shift is a first attenuator for attenuating the output signal from the first phase shifter 4a, and 6 is a first attenuator for changing the output signal from the first attenuator 5a. Amplifies the signal, the above-described polarization splitter 10, transmission / reception switch 3, primary radiator 2
A first amplifier 4b for transmitting horizontally polarized radio waves to the synthetic aperture radar 1 via the second phase shifter 4b for changing the phase shift for each pulse with respect to the vertically polarized wave reception signal from the polarization splitter 10 ,
Reference numeral 5b denotes a second attenuator for attenuating the output signal from the second phase shifter 4b, and 6b amplifies the output signal from the second attenuator 5b, and the polarization splitter 10, the transmission / reception switch 3. A second amplifier 7 for transmitting a vertically polarized radio wave to the synthetic aperture radar 1 via the primary radiator 2;
It is a metal surface offset parabola for converting to Field.

Next, the operation will be described. In the synthetic aperture radar test apparatus configured as described above, the radio wave transmitted from the synthetic aperture radar 1 is converted from the Near Field radio wave into the Far Field by the metal surface offset parabola 7 as in the first embodiment. It is received at the primary radiator 2 of the target generator located at the focal point of the parabola. After passing through the transmission / reception switch 3, this radio wave is split by the polarization splitter 10 into a horizontally polarized wave and a vertically polarized wave. As in the first embodiment, the phase outputs of the respective polarization outputs are output by the phase shifter 4a for the horizontal polarization, and the attenuators 5
After the amplitude value is changed by a and amplified by the amplifier 6a, the phase shift value is changed by the phase shifter 4b and the amplitude value is changed by the attenuator 5b for the vertically polarized wave.
After the amplification, the horizontally polarized radio wave and the vertically polarized radio wave are synthesized again by the polarizer / demultiplexer 10, and the primary radiator 2 is transmitted from the primary radiator 2 via the transmission / reception switch 3 to the metal surface offset parabola 7.
Sent to. This radio wave is converted again to Far Field by the metal surface offset parabola 7,
By being received by the synthetic aperture radar 1 and subjected to the synthetic aperture processing, the point image response of the entire multi-polarization synthetic aperture radar system having horizontal polarization and vertical polarization is simultaneously evaluated.

Embodiment 5 5 shows a fifth embodiment of the present invention. In the figure, reference numeral 1 denotes a synthetic aperture radar as a device under test, and 2 denotes a primary radiator for transmitting and receiving radio waves to and from the synthetic aperture radar 1. 3 is the primary radiator 2
, A transmission / reception switch 11 for switching between transmission and reception, 11 is a duplexer for distributing input / output signals of the transmission / reception switch 3 for each frequency, and 4a is a pulse for a received signal having the first frequency from the duplexer 11. , A first attenuator for attenuating the output signal from the first phase shifter 4a, and 6a for an output signal from the first attenuator 5a. The signal is amplified, and the duplexer 11, the transmission / reception switch 3,
A first amplifier for transmitting a radio wave of a first frequency to the synthetic aperture radar 1 via the primary radiator 2, and 4 b changes a phase shift for each pulse with respect to a received signal having a second frequency from the demultiplexer 11. The second phase shifter 5b
The second attenuator 6b attenuates the output signal from the second attenuator b, amplifies the output signal from the second attenuator 5b, and combines the output signal from the duplexer 11, the transmission / reception switch 3, and the primary radiator 2 into a synthetic aperture. An amplifier 7 for transmitting a radio wave of the second frequency to the radar 1.
It is a metal surface offset parabola for converting a Field to a Far Field.

Next, the operation will be described. In the synthetic aperture radar test apparatus configured as described above, the radio wave transmitted from the synthetic aperture radar 1 is converted from the Near Field radio wave into the Far Field by the metal surface offset parabola 7 as in the first embodiment. It is received at the primary radiator 2 of the target generator located at the focal point of the parabola. After passing through the transmission / reception switch 3, this radio wave is split by the splitter 11 into two radio waves of a first frequency and a second frequency. The radio wave output having each frequency is supplied to the phase shifter 4 for the first frequency as in the first embodiment.
After the phase shift value is changed by the attenuator 5 and the amplitude value is changed by the attenuator 5 and amplified by the amplifier 6, the phase shift value of the second frequency is changed by the phase shifter 4b, and the amplitude value is changed by the attenuator 5b. 6b, the radio wave having the first frequency by the splitter 11 again,
Are transmitted from the primary radiator 2 to the metal surface offset parabola 7 via the transmission / reception switch 3. This radio wave is converted again into a Far Field by the metal surface offset parabola 7, received by the synthetic aperture radar 1, and subjected to the synthetic aperture processing to simultaneously evaluate the point image response of the entire multi-frequency synthetic aperture radar system. become. Although the number of frequencies is 2 in this example, this number can be increased to an arbitrary value by adding a duplexer.

Embodiment 6 FIG. FIG. 6 shows a sixth embodiment of the present invention. In the figure, reference numeral 1 denotes a synthetic aperture radar, which is a device under test, and 2 denotes a primary radiator for transmitting and receiving radio waves to and from the synthetic aperture radar 1. 3 is the primary radiator 2
, A transmission / reception switch for switching between transmission and reception, 11 is a duplexer for distributing the input / output signal of the transmission / reception switch 3 for each frequency, and 10a is a signal for dividing the signal having the first frequency from the duplexer for each polarization. A first polarization splitter 4a for distributing, a first phase shifter for changing a phase shift for each pulse with respect to the horizontal polarization reception signal having the first frequency from the polarization splitter 10,
5a is a first attenuator for attenuating the output signal from the first phase shifter 4a, and 6 is an amplifier for amplifying the output signal from the first attenuator 5a. 11, a first amplifier for transmitting a horizontally polarized radio wave having a first frequency to the synthetic aperture radar 1 via the transmission / reception switch 3, and the primary radiator 2, 4b is a first amplifier from the polarization splitter 10 A second phase shifter 5b for changing the phase shift for each pulse with respect to the vertically polarized reception signal having a frequency, a second attenuator 5b for attenuating an output signal from the second phase shifter 4b, and 6b The output signal from the second attenuator 5b is amplified and the polarization splitter 10,
A second amplifier 10b for transmitting a vertically polarized radio wave having a first frequency to the synthetic aperture radar 1 via the duplexer 11, the transmission / reception switch 3, and the primary radiator 2 is connected to the second amplifier 10b. The second polarization splitter 4c distributes the signal having the frequency of 2 for each polarization, and the phase shifter 4c shifts the phase of the horizontal polarization reception signal having the second frequency from the polarization splitter 10b for each pulse. The third phase shifter 5c to be changed is a third attenuator that attenuates the output signal from the third phase shifter 4c, and 6c amplifies the output signal from the third attenuator 5c. A third amplifier for transmitting a horizontally polarized radio wave having a second frequency to the synthetic aperture radar 1 via the polarization demultiplexer 10b, the demultiplexer 11, the transmission / reception switch 3, and the primary radiator 2; Duplexer 10
The fourth phase shifter 5d that changes the phase shift for each pulse with respect to the vertically polarized reception signal having the second frequency from b. The fourth phase shifter 5d attenuates the output signal from the fourth phase shifter 4d. The attenuator 6d amplifies the output signal from the fourth attenuator 5d, and amplifies the output signal to the synthetic aperture radar 1 via the polarization splitter 10b, the duplexer 11, the transmission / reception switch 3, and the primary radiator 2. A fourth amplifier for transmitting vertically polarized radio waves having a frequency of 2;
Is Nea for radio waves input to and output from the synthetic aperture radar 1.
It is a metal surface offset parabola for converting from r Field to Far Field.

Next, the operation will be described. In the synthetic aperture radar test apparatus configured as described above, the radio wave transmitted from the synthetic aperture radar 1 is converted from the Near Field radio wave into the Far Field by the metal surface offset parabola 7 as in the first embodiment. It is received at the primary radiator 2 of the target generator located at the focal point of the parabola. After passing through the transmission / reception switch 3, this radio wave is split by the splitter 11 into two radio waves of a first frequency and a second frequency. The radio wave output having each frequency is further distributed to two systems of a horizontal polarization component and a vertical polarization component by the polarization splitter 10a and the second polarization splitter 10b. As a result, the radio waves are divided into a total of four radio waves of two frequencies and two polarizations. As in the first embodiment, the phase shift value of the horizontal polarization of the first frequency is changed by the phase shifter 4a, the amplitude value is changed by the attenuator 5a, and amplified by the amplifier 6a. For the polarization, the phase shift value is changed by the phase shifter 4b, the amplitude value is changed by the attenuator 5b, and after being amplified by the amplifier 6b,
For the horizontal polarization of the second frequency, the phase shift value is changed by the phase shifter 4c, the amplitude value is changed by the attenuator 5c, and amplified by the amplifier 6c. Then, for the vertical polarization of the second frequency, the phase shifter is changed. After the phase shift value is changed by 4d and the amplitude value is changed by attenuator 5d, and amplified by amplifier 6d, horizontal polarization having the first frequency is again performed by polarization splitter 10a or polarization splitter 10b and duplexer 11. The radio wave, the vertically polarized wave, the horizontally polarized wave having the second frequency, and the vertically polarized wave are synthesized and transmitted from the primary radiator 2 to the metal surface offset parabola 7 via the transmission / reception switch 3. You. This radio wave is again converted to Far Field by the metal surface offset parabola 7 and the synthetic aperture radar 1
The multi-polarized, multi-frequency, synthetic aperture radar system simultaneously evaluates the point image response by receiving and performing the synthetic aperture processing. Although the number of frequencies is 2 in this example, this number can be increased to an arbitrary value by adding a duplexer.

Embodiment 7 FIG. FIG. 7 is a view showing a seventh embodiment of the present invention. In the figure, reference numeral 1 denotes a synthetic aperture radar as a device under test, and 2 denotes a primary radiator for transmitting and receiving radio waves to and from the synthetic aperture radar 1. 3 is the primary radiator 2
, A transmission / reception switch 4 for switching between transmission and reception, 4 is a phase shifter for changing the phase shift of the received signal from the transmission / reception switch 3 for each pulse, and 5 is an attenuation for attenuating the output signal from the phase shifter 4. The amplifier 6 amplifies the output signal from the attenuator 5 and transmits an electric wave to the synthetic aperture radar 1 via the transmission / reception switch 3 and the primary radiator 2, and the input / output 7 to the synthetic aperture radar 1. Near Field for radio waves
This is a metal surface offset parabola for converting from to Far Field. Reference numeral 12a denotes a first pseudo target generator composed of the primary radiator 2, the transmission / reception switch 3, the phase shifter 4, the attenuator 5, and the amplifier 6, and 12b denotes the first pseudo target generator 12a. Second of similar configuration
The pseudo target generator 12c is a third pseudo target generator also having the same configuration as the first pseudo target generator.

Next, the operation will be described. The first pseudo target generator 12a itself performs exactly the same operation as that of the first embodiment when used in combination with the synthetic aperture radar 1 and the metal surface offset parabola 7. By combining the second pseudo target generator 12b and the third pseudo target generator 12c in parallel in the elevation direction, the synthetic aperture radar performs scanning S
AR can be used to evaluate the system when the elevation direction scans the beam. That is, when the beam of the synthetic aperture radar 1 is at the beam position 1 (elevation position, the same applies hereinafter), the first pseudo target generator 12a is used to receive a target signal. The target signal is received using the second pseudo target generator 12b, and the target signal is received using the third pseudo target generator 12c when in the beam position 3. In this manner, the target signal can be continuously received while scanning the beam at a high speed.
A point image evaluation test in the R mode can be performed. Also, by changing the generated signal pattern (absolute value of phase shift, amplitude, etc.) of each pseudo target generator, scan SAR
Sometimes it can be a means to confirm that the beam at each beam position has been scanned. Although the number of beam spots is set to 3 in this example, this number can be increased to an arbitrary number by adding a pseudo target generator.

Embodiment 8 FIG. FIG. 8 is a view showing an eighth embodiment of the present invention. In the figure, reference numeral 1 denotes a synthetic aperture radar as a device under test, and 2 denotes a primary radiator for transmitting and receiving radio waves to and from the synthetic aperture radar 1. 3 is the primary radiator 2
, A transmission / reception switch for switching between transmission and reception, 10 a polarization splitter for distributing the input / output signal of the transmission / reception switch 3 for each polarization, 18 a horizontal polarization reception signal from the polarization splitter 10 and a vertical polarization A polarization change switch for switching a signal for each pulse, 4 is a phase shifter for changing the phase shift for each pulse with respect to the output signal from the polarization change switch 18, and 5 is an attenuator for the output signal from the phase shifter 4. The attenuator 6 for amplifying the output signal from the attenuator 5 and the polarization changeover switch 1
8, an amplifier for transmitting horizontally and vertically polarized radio waves to the synthetic aperture radar 1 via the polarization splitter 10, the transmission / reception switch 3, and the primary radiator 2, and 7 is a radio wave input to and output from the synthetic aperture radar 1. From Near Field to Far Field
It is a metal surface offset parabola to convert to.

Next, the operation will be described. In the synthetic aperture radar test apparatus configured as described above, the radio wave transmitted from the synthetic aperture radar 1 is converted from the Near Field radio wave into the Far Field by the metal surface offset parabola 7 as in the first embodiment. It is received at the primary radiator 2 of the target generator located at the focal point of the parabola. After passing through the transmission / reception switch 3, the radio wave is split by the polarization splitter 10 into a horizontally polarized wave and a vertically polarized wave. Horizontal or vertical is selected for each polarization output by the polarization changeover switch 18 for each pulse, and the phase shift value is attenuated by the phase shifter 4 for any of the polarization reception signals in the same manner as in the first embodiment. The amplitude value is changed by the device 5,
After being amplified by the amplifier 6, the polarization switch 1
8, transmitted from the primary radiator 2 to the metal surface offset parabola 7 via the polarization splitter 10 and the transmission / reception switch 3. This radio wave is converted again into a Far Field by the metal surface offset parabola 7, received by the synthetic aperture radar 1, and subjected to the synthetic aperture processing so that a multi-polarization synthetic aperture radar composed of horizontal polarization and vertical polarization. The point spread response of the entire system will be evaluated simultaneously for each pulse.

Embodiment 9 FIG. 9 is a view showing a ninth embodiment of the present invention. In the figure, reference numeral 1 denotes a synthetic aperture radar, which is a device under test, and 2 denotes a primary radiator for transmitting and receiving radio waves to and from the synthetic aperture radar 1. 3 is the primary radiator 2
And 4a are first phase shifters that change the phase shift for each pulse with respect to the received signal from the duplexer 11, and 5 is an attenuator for the output signal from the phase shifter 4a. The first attenuator 19 is the transmission / reception switch 3
And 4b are second phase shifters for changing the phase shift for each pulse with respect to the delayed received signal from the delay line 19, and 5b is the above phase shifter. A second attenuator for attenuating the output signal from 4b,
20 is a directional coupler that combines the outputs of the first and second attenuators 5a and 5b, and 6 is the directional coupler 20.
An amplifier for amplifying an output signal from the multiplexing unit and transmitting a radio wave to the synthetic aperture radar 1 via the transmission / reception switch 3 and the primary radiator 2;
7 is Ne for radio waves input to and output from the synthetic aperture radar 1.
It is a metal surface offset parabola for converting from ar Field to Far Field.

Next, the operation will be described. In the synthetic aperture radar test apparatus configured as described above, the radio wave transmitted from the synthetic aperture radar 1 is converted from the Near Field radio wave into the Far Field by the metal surface offset parabola 7 as in the first embodiment. It is received at the primary radiator 2 of the target generator located at the focal point of the parabola. This radio wave passes through the transmission / reception switch 3 and then passes through the delay line 19 and is split into a radio wave having a delay and a radio wave that passes through the delay line 19 as it is. As in the first embodiment, each radio wave output changes the phase shift value by the phase shifter 4 and the amplitude value by the attenuator 5a for the first target signal that does not pass through the delay line.
Is passed through the phase shifter 4b
To change the phase shift value, the amplitude value by the attenuator 5b, and combine the outputs of both by the directional coupler 20, then amplify by the amplifier 6, and send the metal from the primary radiator 2 through the transmission / reception switch 3. It is transmitted toward the plane offset parabola 7. This radio wave is a metal surface offset parabola 7
Is converted again into Far Field, and is received by the synthetic aperture radar 1 and subjected to the synthetic aperture processing, whereby the point image responses of a plurality of targets in the entire synthetic aperture radar system are evaluated simultaneously. As a result, a dynamic range that cannot be tested unless a plurality of targets are present is confirmed (the level of the first target is increased and the level of the second target is decreased).
It is possible to check the radiometric accuracy (an accuracy range in which the level difference between the first target and the second target is to be measured). Although the number of targets is set to 2 in this example, this number can be increased to an arbitrary value by adding a delay line, a phase shifter, and an attenuator.

Embodiment 10 FIG. FIG. 10 shows a tenth embodiment of the present invention. In the figure, reference numeral 1 denotes a synthetic aperture radar, which is a device under test, and 2 denotes a primary radiator for transmitting and receiving radio waves to and from the synthetic aperture radar 1. Reference numeral 3 denotes a transmission / reception switch for switching between transmission and reception in the primary radiator 2;
a is a first phase shifter that changes the phase shift for each pulse with respect to the received signal from the duplexer 11, 5a is a first attenuator that attenuates the output signal from the phase shifter 4a, and 19 is the first attenuator. A delay line 4b for temporally delaying a signal obtained by distributing an output from the transmission / reception switch 3 is a second phase shifter 5b for changing a phase shift for each pulse with respect to the delayed reception signal from the delay line 19.
Is a second attenuator for attenuating an output signal from the phase shifter 4b, and 20 is a first attenuator 5a and a second attenuator 5
A directional coupler 6 for synthesizing the output of b is an amplifier for amplifying the output signal from the directional coupler 20 and transmitting a radio wave to the synthetic aperture radar 1 via the transmission / reception switch 3 and the primary radiator 2. is there.

Next, the operation will be described. In this embodiment, the test apparatus operates as an active radar calibrator which is one means of external calibration. In this case, the radio wave from the synthetic aperture radar 1 is received by the synthetic aperture radar test device, and the signal transmitted by the synthetic aperture radar test device is again received by the synthetic aperture radar 1,
Calibrate the entire radar system by measuring the amplitude.
In the synthetic aperture radar test apparatus configured as described above, the radio wave transmitted from the synthetic aperture radar 1 propagates in the air and is received by the primary radiator 2. This radio wave passes through the transmission / reception switch 3 and then passes through the delay line 19 and is split into a radio wave having a delay and a radio wave that passes through the delay line 19 as it is. As in the first embodiment, each radio wave output passes through the delay line 19 for the first target signal that does not pass through the delay line by changing the phase shift value by the phase shifter 4a and the amplitude value by the attenuator 5a. For the second target signal, the phase shift value is changed by the phase shifter 4b, the amplitude value is changed by the attenuator 5b, the outputs of both are combined by the directional coupler 20, and then amplified by the amplifier 6; The signal is transmitted from the primary radiator 2 to the synthetic aperture radar 1 via the radiator 3. After the radio waves propagate through the air again, they are received by the synthetic aperture radar 1, subjected to synthetic aperture processing, and evaluated for amplitude and phase shift, so that external calibration by multiple targets in the synthetic aperture radar 1 is performed simultaneously. Become. In addition,
In this example, the number of targets is two, but this number can be increased to any value by adding a delay line, a phase shifter, and an attenuator. Although the tenth aspect of the present invention does not solve the problem that it has to be performed outdoors at a distance of about several kilometers, active radar calibration is actually carried out in a state of being mounted on a satellite. In order to compare with a fixed point on the ground, it is not a problem in this case.

[0043]

According to the first aspect of the present invention, Near Fie
Converting ld equivalently to Far Field enables comprehensive indoor synthetic aperture radar system testing.

According to the second aspect of the present invention, it is possible to reduce the amount of metal as a material by using a mesh type column parabolic mirror. In addition to the effects of the first aspect, the weight of the test apparatus can be further reduced. In addition, the cost can be reduced.

According to the third aspect of the present invention, a synthetic indoor radar system comprehensive test can be performed in a narrow indoor space with the beam scanned by rotating the synthetic aperture radar by the antenna turntable.

According to the fourth aspect of the present invention, a synthetic aperture radar system comprehensive test can be performed in a narrow indoor space at the same time by using a polarization splitter.

According to the fifth aspect of the present invention, the use of the duplexer makes it possible to perform a synthetic indoor radar system comprehensive test in a narrow indoor space at a plurality of frequencies simultaneously.

According to the sixth aspect of the present invention, the use of the demultiplexer and the two polarization demultiplexers makes it possible to perform a synthetic indoor radar system comprehensive test in a narrow indoor space at a plurality of frequencies and a plurality of polarizations simultaneously.

According to the seventh aspect, the scan SAR (S
A synthetic indoor radar system comprehensive test in a narrow indoor space can be performed in the synthetic aperture radar mode, and at the same time, the function verification of the scan SAR can be realized.

According to the eighth aspect of the present invention, the use of the polarization splitter and the polarization changeover switch makes it possible to perform a synthetic indoor radar system comprehensive test in a narrow indoor space at the same time without increasing the number of hardware. Becomes

According to the ninth aspect of the present invention, a synthetic test of a synthetic aperture radar system can be performed in a narrow room at the same time by using a delay line.

According to the tenth aspect, by using the delay line, external calibration of the synthetic aperture radar by the active radar calibration method for a plurality of targets simultaneously becomes possible.

[Brief description of the drawings]

FIG. 1 is a diagram showing a first embodiment of a synthetic aperture radar test apparatus according to the present invention.

FIG. 2 is a diagram showing a second embodiment of a synthetic aperture radar test apparatus according to the present invention.

FIG. 3 is a diagram showing a third embodiment of a synthetic aperture radar test apparatus according to the present invention.

FIG. 4 is a diagram showing a fourth embodiment of a synthetic aperture radar test apparatus according to the present invention.

FIG. 5 is a diagram showing a fifth embodiment of the test apparatus for a synthetic aperture radar according to the present invention.

FIG. 6 is a diagram showing a sixth embodiment of the synthetic aperture radar test apparatus according to the present invention.

FIG. 7 is a diagram showing Embodiment 7 of a synthetic aperture radar test apparatus according to the present invention.

FIG. 8 is a diagram showing Embodiment 8 of a synthetic aperture radar test apparatus according to the present invention.

FIG. 9 is a diagram showing a ninth embodiment of a test apparatus for a synthetic aperture radar according to the present invention.

FIG. 10 is a diagram showing a tenth embodiment of a test apparatus for a synthetic aperture radar according to the present invention.

FIG. 11 is a view showing a conventional synthetic aperture radar test apparatus.

FIG. 12 is a diagram illustrating the principle of a synthetic aperture radar.

FIG. 13 is a diagram showing a phase shift and an amount of attenuation set in a phase shifter and an attenuator.

[Explanation of symbols]

1 Synthetic aperture radar, 2 primary radiator, 3 duplexer, 4 phase shifter, 5 attenuator, 6 amplifier, 7 metal plane offset parabola, 8 mesh plane offset parabola, 9 antenna turntable, 10 polarization splitter, 11 splitter, 12 pseudo target generator, 13 radar beam, 14 ground, 15 hours, 16 phase shift, 17 attenuation, 18 polarization switch, 19 delay line, 20
Directional coupler.

Continuation of the front page (56) References JP-A-2-45788 (JP, A) JP-A-6-230108 (JP, A) JP-A-61-38580 (JP, A) JP-A-61-38579 (JP) JP-A-61-38578 (JP, A) JP-A-3-110386 (JP, U) JP-A-6-47884 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB G01S 7/00-7/42 G01S 13/00-13/95

Claims (9)

(57) [Claims] 1. The method according to claim 1, further comprising the step of detecting N from a synthetic aperture radar as a device under test.
a metal surface offset parabola for converting the radio wave of the ear field into a far field, and a primary radiator arranged at a focal position of the metal surface offset parabola for transmitting and receiving a radio wave between the synthetic aperture radar, A transmission / reception switch for switching between transmission and reception in the primary radiator, a phase shifter for changing a phase shift for each pulse with respect to a reception signal from the transmission / reception switch, and an attenuation for attenuating an output signal from the phase shifter A synthetic aperture radar test apparatus, comprising: an amplifier for amplifying an output signal from the attenuator and transmitting a radio wave from the primary radiator via the duplexer. 2. The method according to claim 1, wherein N is a signal from a synthetic aperture radar.
a mesh plane offset parabola for converting the radio wave of the ear field into a far field, and a primary radiator arranged at a focal position of the mesh plane offset parabola for transmitting and receiving a radio wave between the synthetic aperture radar, A transmission / reception switch for switching between transmission and reception in the primary radiator, a phase shifter for changing a phase shift for each pulse with respect to a reception signal from the transmission / reception switch, and an attenuation for attenuating an output signal from the phase shifter A synthetic aperture radar test apparatus, comprising: an amplifier for amplifying an output signal from the attenuator and transmitting a radio wave from the primary radiator via the duplexer. 3. An antenna turntable for supporting a synthetic aperture radar as a device under test, and Nea from the synthetic aperture radar.
a metal surface offset parabola for converting an r Field radio wave into a Far Field, and a primary radiator arranged at a focal position of the metal surface offset parabola for transmitting and receiving radio waves between the synthetic aperture radar, A transmission / reception switch for switching between transmission and reception in the primary radiator, a phase shifter for changing a phase shift for each pulse with respect to a reception signal from the transmission / reception switch, and an attenuation for attenuating an output signal from the phase shifter A synthetic aperture radar test apparatus, comprising: an amplifier for amplifying an output signal from the attenuator and transmitting radio waves from the primary radiator via the duplexer. 4. An N- beam from a test object synthetic aperture radar.
a metal surface offset parabola for converting the radio wave of the ear field into a far field, and a primary radiator arranged at a focal position of the metal surface offset parabola for transmitting and receiving a radio wave between the synthetic aperture radar, In the primary radiator, a transmission / reception switch that switches between reception and reception, a polarization splitter that distributes input / output signals of the transmission / reception switch for each polarization, and a horizontal polarization reception signal from the polarization splitter. A phase shifter that changes the phase shift for each pulse, an attenuator that attenuates the output signal from the phase shifter, and amplifies the output signal from the attenuator, via the polarization splitter, and a duplexer. An amplifier for transmitting a horizontally polarized radio wave from the primary radiator, a second phase shifter for changing a phase shift for each pulse with respect to the vertically polarized reception signal from the polarization splitter, From the second phase shifter A second attenuator for attenuating an output signal, and amplifying the output signal from the second attenuator, and transmitting vertically polarized radio waves from the primary radiator via the polarization splitter and the duplexer. And a second amplifier for testing the synthetic aperture radar. 5. An N- beam from a test object synthetic aperture radar.
a metal surface offset parabola for converting the radio wave of the ear field into a far field, and a primary radiator arranged at a focal position of the metal surface offset parabola for transmitting and receiving a radio wave between the synthetic aperture radar, A transmission / reception switch for switching transmission and reception in the primary radiator, a duplexer for distributing input / output signals of the transmission / reception switch for each frequency, and a reception signal having a first frequency from the duplexer. A phase shifter that changes the phase shift for each pulse, and an attenuator that attenuates an output signal from the phase shifter,
An amplifier for amplifying an output signal from the attenuator, transmitting an electric wave of a first frequency from the primary radiator via the duplexer and the duplexer, and a second frequency from the duplexer A second phase shifter that changes the phase shift for each pulse with respect to the received signal, a second attenuator that attenuates the output signal from the second phase shifter, and a second attenuator. A second signal for amplifying the output signal of the first radiator and transmitting a radio wave of a second frequency from the primary radiator via the duplexer and the duplexer.
Synthetic Aperture Radar test equipment consisting of an amplifier and 6. N from a synthetic aperture radar which is a device under test.
a metal surface offset parabola for converting the radio wave of the ear field into a far field, and a primary radiator arranged at a focal position of the metal surface offset parabola for transmitting and receiving a radio wave between the synthetic aperture radar, A transmission / reception switch for switching between transmission and reception in the primary radiator, a duplexer for distributing input / output signals of the transmission / reception switch for each frequency, and a signal having a first frequency from the duplexer for polarization. And a phase shifter for changing a phase shift for each pulse with respect to a horizontally polarized reception signal having a first frequency from the polarization splitter, and an output from the phase shifter An attenuator for attenuating a signal, amplifying an output signal from the attenuator, and transmitting a horizontally polarized radio wave of a first frequency from the primary radiator via the polarization splitter, the duplexer, and the transmission / reception switch. Increase to send Phase shifter, a second phase shifter for changing a phase shift for each pulse with respect to a vertically polarized reception signal having a first frequency from the polarization splitter, and an output signal from the second phase shifter Amplifying the output signal from the second attenuator, and amplifying the output signal from the primary radiator through the polarization splitter, the duplexer, and the duplexer to transmit the vertical signal of the first frequency. A second amplifier for transmitting polarized radio waves, a second polarization splitter for distributing a signal having a second frequency from the splitter for each polarization, and a second polarization splitter. A third phase shifter that changes the phase shift for each pulse with respect to the horizontally polarized reception signal having the second frequency from the wave shifter, and a third phase attenuator that attenuates the output signal from the third phase shifter. Amplifying the output signal from the attenuator and the third attenuator, and amplifying the primary radiation via the second polarizer / demultiplexer, duplexer, and duplexer. A third amplifier for transmitting horizontally polarized radio waves of the second frequency from the device;
A fourth phase shifter that changes the phase shift for each pulse with respect to the vertically polarized reception signal having the second frequency from the second polarization splitter, and an output signal from the fourth phase shifter Amplifying the output signal from the fourth attenuator, and amplifying the output signal from the primary radiator via the second polarization splitter, duplexer, and duplexer. A synthetic aperture radar test apparatus, comprising: a fourth amplifier for transmitting a vertically polarized radio wave of a frequency. 7. N from a synthetic aperture radar as a device under test
a metal surface offset parabola for converting the radio wave of the ear field into a far field, and a primary radiator arranged at a focal position of the metal surface offset parabola for transmitting and receiving a radio wave between the synthetic aperture radar, A transmission / reception switch for switching between transmission and reception in the primary radiator, a phase shifter for changing a phase shift for each pulse with respect to a reception signal from the transmission / reception switch, and an attenuation for attenuating an output signal from the phase shifter And an amplifier for amplifying the output signal from the attenuator and transmitting radio waves from the primary radiator via the duplexer, the primary radiator, duplexer, phase shifter, attenuator, A first pseudo target generator having an amplifier as a component, a second pseudo target generator having the same components, and a second pseudo target generator having the same components. Synthetic aperture radar test device comprising a pseudo target generator. 8. An N- beam from a test object synthetic aperture radar.
a metal surface offset parabola for converting the radio wave of the ear field into a far field, and a primary radiator arranged at a focal position of the metal surface offset parabola for transmitting and receiving a radio wave between the synthetic aperture radar, A transmission / reception switch for switching between transmission and reception in the primary radiator, a polarization splitter for distributing an input signal of the transmission / reception switch for each polarization, a horizontal polarization reception signal and a vertical polarization from the polarization splitter. A polarization changeover switch for switching a wave reception signal for each pulse, a phase shifter for changing a phase shift for each pulse with respect to the polarization changeover switch output signal, and an attenuator for attenuating an output signal from the phase shifter. And an amplifier for amplifying the output signal from the attenuator, transmitting the radio wave from the primary radiator via the polarization switch, the polarization splitter, and the duplexer. That synthetic aperture radar test equipment. 9. N from a synthetic aperture radar which is a device under test.
a metal surface offset parabola for converting the radio wave of the ear field into a far field, and a primary radiator arranged at a focal position of the metal surface offset parabola for transmitting and receiving a radio wave between the synthetic aperture radar, A transmission / reception switch for switching between transmission and reception in the primary radiator, a phase shifter for changing a phase shift for each pulse with respect to a reception signal from the transmission / reception switch, and an attenuation for attenuating an output signal from the phase shifter A delay line for delaying a branch output from the transmission / reception switch, a second phase shifter for changing a phase shift for each pulse with respect to a signal from the delay line, and a second phase shifter. Attenuator for attenuating the output signal of the second attenuator, a directional coupler for combining the output signal from the attenuator and the output signal from the second attenuator, and an output signal from the directional coupler Amplifies, synthetic aperture radar test device comprising an amplifier for transmitting a radio wave from the primary radiator above via the duplexer.