JPH0738531B2 - Antenna mirror surface distortion detector - Google Patents

Description

The present invention relates to a device for detecting mirror surface distortion of an antenna operating in wireless communication.

<Prior Art> Conventionally, there are an example of using a laser beam and an example of using a radio wave as a method for detecting the mirror surface distortion of an antenna.

Mirror surface distortion detection method by laser light: This method is an example used for a large earth station antenna for space communication with an aperture diameter of about 40 m, and the incident light is incident at an appropriate position on the antenna mirror surface as an auxiliary tool. An appropriate number of corner cubes that reflect in this direction are provided, each corner cube is irradiated with laser light, and the variation in the installation position of the corner cube, that is, the amount of mirror surface distortion is detected from the reflected light.

Radio wave specular distortion detection method: This method is an example used for a large antenna for space communication, and it scans the antenna mechanically within a predetermined angle range while receiving radio waves from radio stars or artificial satellites. By doing so, the antenna pattern is obtained, and the mirror surface distortion amount is detected based on the result (reference document, Y. Rahmat-Sam.
ii `` Surface diagnosis of large reflection antenn
as using microwave holographic metrology: An iterat
ive approach '', Radio Science, Vol.19, No.5, pp.1205-1
217, Sep.-Oct, 1984).

A conventional detection technique using radio waves will be described with reference to FIG. In FIG. 7, 1 is a radio wave oscillating source, 2 is a transmitting antenna, and these can be replaced by radio stars.
3 is a communication antenna for detecting mirror surface distortion (mirror surface distortion detection communication antenna), 4 is a phase reference antenna installed near the antenna 3, 5 is a receiver, and 6 is a signal processing device.

In order to detect the mirror surface distortion, the antenna 3 mechanically changes the pointing direction at the theoretically obtained angular interval, and receives the radio wave from the radio wave oscillation source 1 each time. On the other hand, the antenna 4 always orients the power source oscillation source 1 in a constant direction and receives radio waves. Both antennas
The reception radio waves of 3 and 4 are transmitted to the receiver 5. The receiver 5 detects the amplitude and phase of the signal sent from the antenna 3 with reference to the signal from the antenna 4, and sends it to the signal processing device 6. The signal processing device 6 analyzes the pointing direction of the antenna 3 and the amplitude and phase data of the received radio wave, and calculates the electric field distribution on the aperture plane of the antenna 3. This allows
Detects specular distortion. The principle is that the phase distribution in the electric field distribution, in particular, the phase distribution has a one-to-one correspondence with the distortion of the antenna mirror surface, so that obtaining the electric field distribution of the antenna aperture surface can be applied to the detection of the mirror surface distortion.

<Problems to be Solved by the Invention> However, the above two conventional techniques have the following problems.

Mirror distortion detecting method by a laser beam: for corner cube the size of which is approximately 5 × 5 × 5cm ^3, when the antenna opening diameter of about several m, the area occupied by the relatively corner cube can not be ignored , Deteriorate the shape of the communication beam of the antenna.

Since it is an optical detection system, it is necessary to always clean the system.

Since it requires a laser oscillation source, it requires regular maintenance and inspection.

Of the above, and when the mirror surface distortion detection antenna is installed in an unmanned building such as a remote island or mountaintop,
Furthermore, if it is installed in an artificial satellite and is in outer space,
Cleaning, maintenance, and inspection are almost impossible, which is a fatal drawback.

Radio wave specular distortion detection method: Since the specular distortion detection antenna 3 is always required to perform a receiving operation, it cannot be applied, for example, if it is a transmission-only antenna and cannot receive or cannot receive with sufficient performance. .

Further, since it is necessary to scan and drive the antenna 3, detection cannot be performed during communication operation.

Further, as the scanning operation of the antenna 3 changes, environmental conditions such as gravity or heat distribution change every moment, so that the strain to be detected cannot be regarded as constant and the detection error increases.

Furthermore, if the antenna 3 is large, it takes too much time to scan and drive, and in the example of the previous dedication (written by Y. Rahmat-Samii), it takes about 70 minutes to acquire the data in the 121 direction. is doing. The direction of 121 is a rough data acquisition number, and it is easily conceivable that several hours are required to perform more precise measurement. However, if the time is long, fluctuations in heat input to the antenna and wind load are expected during the driving time of the antenna. If such fluctuations occur, the amount of specular distortion changes, and the time fluctuation of the receiver 5 also changes. If there is an error in the analysis.

The present invention solves the above-mentioned problems of the prior art, without adding any auxiliary tool to the antenna mirror surface,
Also, without scanning the antenna mirror surface, a device for detecting the antenna mirror surface distortion by computer processing using a part of the radio wave currently used for communication or a radio wave of a frequency very close to the radio wave used for communication is used. provide.

<Means for Solving the Problem> An antenna specular distortion detection device according to the present invention is a communication antenna for detecting specular distortion, which is provided with a primary radiator that transmits or receives radio waves and forms a beam of the antenna through a reflecting mirror. When,
A device for emitting a communication radio wave or a radio wave of a frequency close to the communication radio wave from this antenna, a receiving antenna facing the antenna, and a receiver connected to the receiving antenna for detecting the amplitude and phase of the received radio wave, And a signal processing device having a calculation and analysis function for collecting and processing the detected forces of the receiver and calculating the phase distribution of the electric field on the aperture surface of the mirror surface distortion detection communication antenna.

<Operation> In the above configuration, the mirror surface distortion detection communication antenna does not need to change its pointing direction, and the receiving antenna is the same. The radio wave received by the receiving antenna may be either the radio wave emitted by the mirror surface distortion detection communication antenna or the radio wave emitted by this antenna.

The principle of antenna mirror surface distortion detection according to the present invention is shown in FIGS.
It will be described with reference to the drawings. In addition, the previous document (Y. Rahmat-Sam
ii) describes a case of mechanically scanning and driving an antenna, but since a signal analysis method for detecting antenna mirror surface distortion using radio waves is described in detail, the principle explanation is given here. stop.

FIG. 2 shows a model for analysis. The position on the aperture surface of the mirror surface strain detection communication antenna 10 is represented by s, and the position on the array surface of the receiving antennas 12 arranged in opposition to this is shown. The position is represented by w. At this time, the directional characteristic P (w) of the antenna 10 is the electric field distribution A at the aperture plane of the antenna 10.
When expressed by (s), it is calculated by the following integral formula (1) (see “Microwave Antenna Theory and Desig” by S. Silver).
n ”p.170, see Dover Publications) P (w) = ∫A (s) · exp (−jk · r (s, w)) ds Equation (1) where ds is the aperture plane of the antenna 10. , R (s, w) is the distance between the position s on the aperture plane of the antenna 10 and the position w on the array plane of the receiving antenna 12, k is the wave number, and k = 2π /
λ and λ are wavelengths.

The above equation (1) can be rewritten as the following equation (2) from the theory of Fourier transform (see, for example, “Mathematical Formula II” by Moriguchi et al., P.261, Iwanami Shoten).

A (s) = ∫P (w) · exp (+ jk · r (s, w)) dw ... Expression (2) In Expression (2), P (w) corresponds to the reception input of the reception antenna 12, and k Since r and (r, s, w) are known or can be measured separately, by connecting the receiver to the receiving antenna 12 and collecting the output from each receiver, and performing the calculation of this equation (2), The electric field distribution A (s) on the aperture plane of the antenna 10 can be obtained. Of course, A (s) includes a phase distribution.

Next, the relationship between the phase distribution on the aperture plane of the antenna 10 and the mirror distortion will be described. As shown in FIG. 3, consider a case where the mirror surface of the antenna 10 is distorted and a part 10a thereof projects by δ in the normal direction of the mirror surface.

Assuming that the angle of incidence of the radio wave on the mirror surface is θ, the path length of the radio wave reaching the point position s on the aperture surface from the focal point F of the antenna 10 via the protrusion 10a is 2δ · cos θ compared to the case without the protrusion 10a. Just shorter.

Multiplying the change in path length by the wave number k is equivalent to obtaining the change in phase on the aperture plane. Therefore, if the phase distribution on the aperture plane is obtained, the distortion amount δ of the mirror surface can be immediately known.

Here, although the primary radiator of the mirror surface distortion detection communication antenna 10 is not shown, the primary radiator has a function of simply transmitting or receiving radio waves and forms a beam of the antenna via a reflecting mirror. This is a sufficient condition for detecting mirror surface distortion. Therefore, in the normal mirror surface distortion detection communication antenna, the primary radiator is installed at the focal position of the reflecting mirror or in the vicinity thereof, which satisfies the above conditions,
No special restrictions are required.

Further, although the antenna 12 is described as an antenna having a reflecting mirror in the figure, this antenna 12 is sufficiently far from the mirror surface distortion detection communication antenna 10 and only needs to be able to receive or transmit radio waves, so An antenna, an array antenna, or a dipole antenna can be used. The position of the primary radiator is arbitrary as long as it functions as an antenna.

Next, the antenna facing the mirror surface distortion detection communication antenna 10
Even if 12 is an antenna having a reflecting mirror and the mirror surface distortion occurs, the mirror surface distortion detection of the mirror surface distortion detection communication antenna 10 is not affected by the following reason. That is, the influence of the mirror surface distortion of the antenna 12 is mainly the deterioration of the pattern and the displacement of the main lobe, and the gain and the phase in the main lobe peak direction hardly change. Therefore, under the condition that the antenna 12 faces the mirror surface distortion detection communication antenna 10, that is, under the condition that the peak direction of the main lobe of the antenna 12 faces the mirror surface distortion detection communication antenna 10, Since the incoming radio wave is received in the peak direction of the main lobe, the specular distortion of the antenna 12 does not affect the specular distortion detection function.

<Example> An example of the present invention will be described with reference to the drawings.

FIG. 1 shows an apparatus according to an embodiment of the present invention. Reference numeral 10 denotes a communication antenna for detecting mirror surface distortion, that is, a mirror surface distortion detecting antenna, which transmits radio waves from a radio wave oscillation source 11 through a primary radiator (not shown). It radiates and is used for transmission. A plurality of receiving antennas 12 are arranged facing the antenna 10. Receiver that detects the amplitude and phase of the received input at each receiving antenna 12
13 are connected, and the output of each receiver 13 is connected to the signal processing device 14.

In operation, the plurality of receiving antennas 12 receive the radio waves transmitted from the antenna 10 during operation. Each receiver 13 detects the amplitude and phase of the radio wave received by the antenna 12, and sends it to the signal processing device 14. Signal processor 14
Inputs the detection signal of each receiver 14 and calculates the electric field distribution on the aperture plane of the antenna 10 by the above-mentioned formula (2). Since the phase distribution in the electric field distribution has a one-to-one correspondence with the distortion of the antenna mirror surface as described above, the signal processing device 14 can calculate the phase distribution on the aperture plane by calculating the wave number k and the incident angle θ. By taking into consideration, the mirror surface distortion can be detected immediately.

In the above-described embodiment, it is not necessary to add any auxiliary equipment other than the one used for communication to the mirror surface distortion detection communication antenna 10, and the receiving antenna 12 and the receiver 13 are almost the same as the wireless stations used for communication. Available. Furthermore,
The signal processing device 14 does not necessarily have to be provided independently, and can be included in any of the wireless stations. Furthermore, since it is not necessary to move the antenna 10 at the time of detecting the mirror surface distortion or stop the transmission and reception of the communication radio wave,
Communication is not interrupted.

Here, the primary radiator of the mirror surface distortion detection communication antenna 10 is not shown in FIG. 1, but as described above, the primary radiator has a function of simply transmitting or receiving radio waves and a reflector. The formation of the beam of the antenna through is a sufficient condition for detecting the mirror surface distortion. Therefore, since the primary radiator is installed at or near the focal point of the reflector in a normal mirror surface distortion detection communication antenna,
The above conditions are satisfied, and no special limiting conditions are required.

As for the receiving antenna 12, an antenna having a reflecting mirror is described as a typical example in FIG. 1, but as described above, this receiving antenna 12 is a mirror surface distortion detection communication antenna 10.
Since it is only necessary to be able to receive radio waves far away from, it is possible to use a horn antenna, an array antenna, or a dipole antenna. The position of the primary radiator is arbitrary as long as it functions as an antenna.

Furthermore, even if the receiving antenna 12 facing the mirrored surface distortion detection communication antenna 10 is an antenna having a reflecting mirror and mirror surface distortion occurs, as described above, in the mirror surface distortion detection of the mirrored surface distortion detection communication antenna 10. Has no effect. That is, the influence of the mirror distortion of the receiving antenna 12 is mainly the pattern deterioration and the main lobe displacement, and the gain and phase in the main lobe peak direction hardly change. Therefore, under the condition that the receiving antenna 12 faces the mirror surface distortion detection communication antenna 10, that is, under the condition that the peak direction of the main lobe of the receiving antenna 12 faces the mirror surface distortion detection communication antenna 10, Radio waves coming from 10 are received in the peak direction of the main lobe, so the receiving antenna
The 12 specular distortions do not affect the specular distortion detection function.

Next, FIG. 4 shows another embodiment of the device of the present invention, in which the mirror surface distortion detection communication antenna 10 is a receiving antenna.

In FIG. 4, an antenna 10 is a receiving antenna for receiving a plurality of radio wave beams, and the antenna 10 is provided near the focal point F.
A plurality of power supply horns 15 that receive the radio waves reflected from 10 are installed. Reference numeral 16 is a transmission antenna facing the antenna 10, and a radio wave oscillation source 17 is connected to the antenna 10 via a primary radiator (not shown). A receiver 13 for detecting the amplitude and phase of the reception input is connected to each horn 15, and the output of each receiver 13 is connected to the signal processing device 14.

As an operation, the radio wave from the oscillation source 17 is radiated to the mirror surface distortion detection communication antenna 10 facing through the transmission antenna 16,
There it is reflected. The radio wave reflected by the mirror surface of the antenna 10 is distributed to each of the plurality of horns 15 near the focal point F corresponding to the installation position of the horn. Each receiver 13 detects the amplitude and phase of the radio wave sent from each horn 15,
It is sent to the signal processing device 14. The signal processing device 14 analyzes the output signal from each receiver 13 and calculates the electric field distribution on the aperture plane of the antenna 10. As described above, there is a one-to-one correspondence between the mirror surface distortion of the antenna 10 and the electric field distribution on the aperture surface, especially the phase distribution thereof. Therefore, by obtaining the electric field distribution on the antenna aperture surface, especially the phase distribution, the mirror surface distortion Can be detected.

In the case of the present embodiment, the electric field distribution on the antenna aperture plane is obtained by the calculation of the expression (6), which is a slightly modified version of the above expression (2). The principle will be described with reference to the analytical model shown in FIG.

The difference between the analysis model of FIG. 5 and that of FIG. 2 is that since there is only one antenna 16 for transmission, the parameter w indicating the installation position of it is constant.
The parameter h indicating the installation position of is introduced.

The above equation (1) considering the position parameter h of the horn 15
When the directional characteristic P (w, h) of the antenna is obtained in the same manner as, the following equation (3) is obtained.

P (w, h) = ∫A (s, h) · exp (−jk · r (s, w)) ds ...
Expression (3) Here, the electric field distribution A (s, h) on the opening surface is a function of not only the position s on the opening surface but also the horn position h. Also, A
(S, h) is expressed by the following equation (4), where Ao (s) is the electric field distribution on the aperture plane when the horn is at the focal point F.

A (s, h) = Ao (s) · exp (jφ (s, h)) Equation (4) Here, φ (s, h) is the phase distribution on the aperture surface according to the installation position of the horn. It is a correction term.

Therefore, by substituting the equation (4) into the equation (3) and omitting the position parameter w of the transmission antenna 16 which can be regarded as a constant, the following equation (5) is obtained.

P (h) = ∫Ao (s) ・ exp (jφ (s, h)) ・ exp (−j
k · r (s)) ds equation (5) This equation (5) can also be rewritten as the following equation (6) by applying the theory of Fourier transform. However, dh
Represents the surface element of the horn array surface.

Ao (s) = exp (+ jk · r (s)) ∫P (h) · exp (-
jφ (s, h)) dh Equation (6) In Equation (6), P (h) corresponds to the reception input of each horn 15, and the wave number k, distance r (s) and phase correction term φ (s). ,
h) is known or can be measured separately. So each horn 15
The signal processing device 14 collects the output from the receiver 13 through the receiver 13 and performs the calculation of equation (6) to obtain the electric field distribution on the aperture plane of the antenna 10 when the horn 15 is at the focal point F. it can.

If the electric field distribution on the antenna aperture is clarified in this way, the distortion amount of the antenna mirror surface can be immediately detected from the phase distribution of the electric field distribution, as already described with reference to FIG.

Here, as the transmitting antenna 16, an antenna having a reflecting mirror is shown as a typical example in FIG. 4, but the transmitting antenna 16 is sufficiently far from the mirror surface distortion detection communication antenna 10 and simply transmits radio waves. As long as it can be used, a horn antenna, an array antenna, or a dipole antenna can be used. The position of the primary radiator is arbitrary as long as it functions as an antenna.

Further, even if the transmission antenna 16 facing the mirror surface distortion detection communication antenna 10 is an antenna having a reflecting mirror and mirror surface distortion occurs, the mirror surface distortion detection communication antenna 10
The detection of the mirror surface distortion is not affected by the following reasons. That is,
The effect of the mirror distortion of the transmitting antenna 16 is mainly the deterioration of the pattern and the displacement of the main lobe, and the gain and phase in the main lobe peak direction hardly change. Therefore, from the viewpoint of the transmitting antenna 16, as long as it is far away,
Specular strain detection communication antenna 10 can only be seen as a point,
Electrically speaking, radio waves only in the peak direction of the main lobe of the transmitting antenna 16 arrive at the mirror surface distortion detection communication antenna 10. As a result, even if the transmitting antenna 16 has a mirror surface distortion, the pattern deterioration caused by the mirror surface distortion does not affect the mirror surface distortion detection of the mirror surface distortion detection communication athena 10.

Even if there is an electrical fluctuation in the peak direction of the main lobe of the transmitting antenna 16, the received signal detected from the power feeding horn 15 via the mirror surface distortion detection communication antenna 10 has the same fluctuation for all the feeding horns. Since they occur, they are canceled in the signal processing of the specular distortion detection, and this also does not affect.

In the embodiment shown in FIG. 4, when the antenna 10 is a multi-beam antenna, a plurality of horns are originally installed and a communication receiver is connected to each horn. Also, by using the receiver, the mirror distortion can be detected without modifying the antenna 10. The installation location of the signal processing device 14 is
As long as there is a means for transmitting the output signal of the receiver 13, it may be at any place regardless of the transmitting side and the receiving side.

Next, referring to FIGS. 6A and 6B, the signal processing device 14
Another embodiment will be described.

In FIG. 6 (b), the signal processing device 14 is provided in the preceding stage,
The pattern correction unit 14a is provided. The output signal of each receiver 13 is sent to the pattern correction unit 14a.

The operation will be described with reference to FIG. When the output signal of the receiver 13 is input to the pattern correction unit 14a, the pattern correction unit 14a stores it in the memory and stores the reference pattern 18 of the mirror surface detection communication antenna 10 and the measurement from each receiver 13 Compare with the value 19. As a result of the comparison, if there is a difference between the reference pattern 18 and the measured value 19, the pattern correction unit 14a, using the reference pattern 18 as a starting point, using an approximation method such as spline approximation, the output signal of each receiver 13 and Build a fix pattern 20 that matches well. The signal processing device 14 receives the correction pattern 20 from the pattern correction unit 14a and treats more points than the actually measured points as if they were measured points.
The electric field distribution on the aperture plane of the antenna is obtained by performing the calculation of the above-mentioned formula (2) or formula (6).

According to the present invention, if the angular interval of the input data at the time of executing the calculation is narrow and the number of data is abundant, the mirror distortion of a fine cycle can be calculated with sufficient accuracy. Therefore, as shown in FIG.
By applying the signal processing of (b) and constructing the modified pattern 20 from the measurement data 19 and the reference pattern 18, the accuracy of mirror surface distortion detection can be improved. Further, by providing the pattern correction unit 14a, it is possible to reduce the number of measurement points without degrading the accuracy of mirror surface distortion detection. In the case of FIG. 1, the number of receiving antennas 12 is used, and in the case of FIG. 4, the feeding horn is used. The number of fifteen can be reduced.

<Effects of the Invention> According to the present invention, a radio wave having a communication frequency or a frequency very close to it is used without adding a special structure, an auxiliary tool, or a special power feeding circuit to a communication antenna, and The mirror distortion of the communication antenna can be detected without any human intervention.

Therefore, it is possible to efficiently and economically detect a remote place, a high place, a place which is not desirable as a human work environment, and a mirror surface distortion of an antenna installed in an artificial satellite.

Further, if a mechanism for correcting the mirror surface distortion is attached in conjunction with the device of the present invention, even if the beam distortion of the communication antenna or the deterioration of the beam shape occurs due to the mirror surface distortion,
Since it can be immediately restored to the normal state, a highly stable wireless communication line can be secured, and further contributes to providing an economical wireless communication line that maximizes the performance of the communication antenna. .

[Brief description of drawings]

FIG. 1 is a block diagram of an apparatus according to an embodiment of the present invention, and FIG.
FIG. 3 is a model diagram for signal analysis in the configuration of FIG. 3, FIG. 3 is a relationship diagram between the antenna mirror surface and the phase distribution on the aperture surface, FIG. 4 is a configuration diagram of another embodiment of the device of the present invention, and FIG. FIG. 6 is a model diagram for signal analysis in the configuration of FIG. 4, FIGS. 6 (a) and 6 (b) are explanatory diagrams and configuration diagrams of another embodiment of the signal processing device, and FIG. 7 is a configuration diagram of a conventional device. is there. In the drawing, 10 is a mirror surface distortion detection communication antenna, 11 and 17 are radio wave oscillating sources, 12 is a receiving antenna, 13 is a receiver, 14 is a signal processing device, 14a is a pattern correction unit thereof, and 15 is power feeding as a receiving antenna. A horn, 16 is a transmitting antenna, 18 is a reference pattern, 19 is a measured value, and 20 is a correction pattern.

Claims (4)

[Claims] Claim: What is claimed is: 1. A mirrored surface distortion detection communication antenna comprising a primary radiator that transmits or receives radio waves and forms a beam of the antenna through a reflecting mirror, and a radio wave for communication from this antenna or a radio wave for communication close to the radio wave for communication. A device that emits radio waves of a frequency, a receiving antenna that faces the antenna, a receiver that is connected to the receiving antenna and that detects the amplitude and phase of the received radio waves, and collects and processes the detected power of the receiver, An antenna specular distortion detection device comprising: a signal processing device having a calculation and analysis function for calculating a phase distribution of an electric field on an aperture surface of a communication antenna. 2. The mirror surface strain detection communication antenna according to claim 1, the device for transmitting a radio wave to the antenna is a radio wave oscillation source, and the receiving antenna is a mirror surface strain detection communication antenna. A plurality of antenna mirror surface distortion detecting devices are characterized in that a plurality of receivers are connected to each receiving antenna in a distributed manner facing each other. 3. The mirror surface distortion detection communication antenna according to claim 1, wherein the mirror surface distortion detection communication antenna is an antenna that receives a plurality of radio wave beams, and a device that emits radio waves to this antenna emits radio waves to the antenna. Antennas that are arranged, the receiving antenna connected to the receiver is a plurality of feeding horns of the mirror surface distortion detection communication antenna, and the receiver is connected to each feeding horn. Detection device. 4. The storage device according to claim 1, 2 or 3, wherein the signal processing device stores an antenna pattern when the mirrored surface distortion detection communication antenna has no mirrored surface distortion. An antenna specular distortion detecting device, characterized in that it has a pattern correcting means for correcting a pattern according to a signal from a receiver in a front stage of the device.