JP2010041577A - Antenna system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain an antenna system allowing a radiation characteristics thereof to be calibrated so as to decrease the amount of gain reduction in comparison with the prior arts when a signal-to-noise ratio of a detection system is low. <P>SOLUTION: The antenna system includes: a means for calculating setting phases of element antennas connected to corresponding phase shifters, when a phased array antenna receives a radio wave for radiation characteristics calibration, on the basis of a change in reception power output from a detection means in rotating setting phases of phase shifters at 360° each sequentially; and a differential phase calculating means for storing a reference value and a comparison value to be used for calibrating a radiation characteristics change of the phased array antenna for the setting phases of the phase shifters calculated twice by the above means and for calculating a differential phase between the reference value and the comparison value. A phase surface of an optimal desired function is calculated from the differential phase and by using a correction phase obtained by the phase surface, exciting phases of element antennas are changed. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an antenna device having a configuration capable of calibrating antenna radiation characteristics of a phased array antenna.

In a phased array antenna, the antenna radiation characteristics may change during antenna operation due to mechanical deformation of the antenna opening surface or changes in the characteristics of the transmission / reception module. Therefore, a technique for detecting and calibrating the characteristic change is required. As a method of detecting the characteristic change, in the conventional phased array antenna, a pickup antenna is arranged, the excitation phase of each element antenna is sequentially changed, and the maximum and minimum values of the array combined power measured using the pickup antenna are measured. There has been a method of measuring the amount of phase change that gives the ratio and its maximum value, and calculating the amplitude and phase of each element antenna from the measured values. (For example, see Patent Document 1)
Furthermore, the above method is used to obtain the differential phase between the initial phase of each element antenna measured during the initial configuration of the phased array antenna and the phase of each element antenna measured by the above method during phased array operation, and this differential phase is determined as the corrected phase. As described above, the excitation phase of each element antenna is changed to calibrate the change in radiation characteristics of the phased array antenna. (For example, see Patent Document 2)

JP-A-57-93267 Japanese Patent Laid-Open No. 2-104104

  In the conventional antenna apparatus as described above, when the signal-to-noise ratio of the detection system is small, the phase amount of each element antenna to be measured includes a large error, and the correction phase obtained from the phase amount is obtained. The amount of error also increases. As a result, if the excitation phase of each element antenna is changed using the correction phase amount including a large error as described above, not only the radiation characteristics cannot be calibrated, but also the radiation pattern changes, resulting in a decrease in gain. there were.

  The present invention has been made to solve the above-described problem, and calculates an optimum desired function phase plane from the differential phase, and uses the correction phase obtained from the phase plane to drive the excitation phase of each element antenna. The purpose of the present invention is to obtain an antenna device capable of calibrating the radiation characteristics so as to reduce the amount of gain reduction compared to the prior art when the signal-to-noise ratio of the detection system is low.

  An antenna device according to the present invention includes a plurality of element antennas, a phase shifter connected to each of the element antennas, a phase shifter control circuit for controlling a set phase of each phase shifter, and each phase shifter. A phased array antenna having a connected power distribution and synthesis circuit, and a detecting means connected to the power distribution and synthesis circuit; and when the phased array antenna receives a radio wave for radiating characteristic calibration, Means for calculating a set phase of an element antenna connected to each corresponding phase shifter based on a change in received power output from the detection means when the set phase is sequentially rotated 360 degrees; The reference value and the comparison value used for calibration of the radiation characteristic change of the phased array antenna of the set phase of each phase shifter calculated by the above means over time are stored. A differential phase calculating means for calculating a differential phase of the value, a phase plane of a desired function is calculated from the differential phase by a predetermined optimization, and a correction phase to be set for each element antenna is calculated based on the calculated phase plane Correction phase calculation means, excitation phase calculation for calculating the excitation phase to be given to each element antenna based on the correction phase and the initial excitation phase preset for each phase shifter, and outputting to the phase shifter control circuit And a circuit.

  In the present invention, the phase plane of the desired function is calculated from the differential phase by a predetermined optimization, and the excitation phase of each element antenna is changed using the correction phase obtained from the phase plane, thereby detecting the signal pair of the detection system. Even when the noise ratio is low, it is possible to obtain an antenna device that can calibrate radiation characteristics so as to reduce the amount of antenna gain reduction.

Embodiment 1 FIG.
FIG. 1 is a configuration explanatory view showing an antenna apparatus according to Embodiment 1 of the present invention. In the figure, a plurality of element antennas 1-n (n = 1, 2, 3,..., N) installed on the phased array antenna opening surface are respectively phase shifters 2-n (n = 1, 2, 3,..., N) are connected to the power distribution / combination circuit 3, and the transmitter 4 is connected to the power distribution / combination circuit 3. The power distribution / combination circuit 3 operates as a power distribution circuit in the direction of the element antenna, and operates as a power combination circuit in the direction of the transmitter 4. Further, a phase shifter control circuit 5 is connected to each of the phase shifters 2-n, and the phase shifter control circuit 5 controls each phase shifter 2-n. A detection circuit 7 is connected to the pickup antenna 6 provided separately from each element antenna 1-n of the phased array antenna, and when the set phase of each phase shifter 2-n of the phased array antenna is changed An element electric field calculation circuit 8 is connected for measuring the received electric power of the element and calculating the amplitude and phase of the element electric field of each element antenna connected to the phase shifter from the change in the received power. Further, the element electric field calculation circuit 8 stores the initial electric field phase φ0, n (n = 1, 2, 3,..., N) of each element antenna obtained by the element electric field calculation circuit 8 at the time of initial antenna configuration. And an initial phase storage circuit 9 that stores the electric field phase φ1, n (n = 1, 2, 3,..., N) of each antenna element obtained by the element electric field calculation circuit 8 during antenna operation. The memory circuit 10 is connected. Note that the initial antenna configuration refers to an antenna configuration before operation of a reference antenna. Further, the initial phase storage circuit 9 and the phase storage circuit 10 are connected to a differential phase calculation circuit 11 that obtains a difference amount of the phase amounts stored in these circuits in order to correct a radiation characteristic change that occurs during antenna operation. . That is, the differential phase calculation circuit 11 is a circuit for obtaining the differential phase φ2, n (n = 1, 2, 3,..., N) of each element antenna by the equation (1).

  Further, the differential phase calculation circuit 11 is connected to the phase plane calculation circuit 12. The phase plane arithmetic circuit 12 is an arithmetic circuit for obtaining a phase plane of a desired function optimum for the differential phase φ2, n obtained by the differential phase arithmetic circuit 11. That is, the phase plane arithmetic circuit 12 is a circuit that obtains the phase plane φs that minimizes the expression (2) by the least square method or the like.

（２）

(2)

In the formula (2), n represents the element antenna number, and in this embodiment, n = 1, 2, 3,. xn and yn represent the positions of the element antennas of the element antenna number n on the phased array antenna opening surface.
Further, the phase plane calculation circuit 12 is connected to the correction phase calculation circuit 13. The correction phase calculation circuit 13 calculates a correction phase φc, n (n = 1, 2, 3,..., N) to be set for each element antenna from the phase plane φs obtained by the phase plane calculation circuit 12. It is. That is, the correction phase calculation circuit 13 obtains the correction phase φc−n to be given to each element antenna by the equation (3).

（３）

(3)

  The correction phase calculation circuit 13 is connected to the excitation phase calculation circuit 14, and the initial excitation phase storage circuit 15 is connected to the excitation phase calculation circuit 14. The excitation phase calculation circuit 14 is a circuit for obtaining the excitation phase Φ1, n to be given to each phase shifter 2-n, and the initial excitation phase storage circuit 15 is the phase shifter control circuit 5 that receives each phase shifter at the initial configuration of the phased array antenna. This is a circuit for storing the initial excitation phase Φ0, n (n = 1, 2, 3,..., N) applied to the phase shifter 2-n. That is, the excitation phase calculation circuit 14 obtains the excitation phase Φ1, n (n = 1, 2, 3,..., N) to be given to each phase shifter 2-n by the following equation 4.

（４）

(4)

In the antenna device configured as described above, the radiation characteristic is calibrated by the procedure shown in FIGS. Here, FIGS. 2 and 3 are diagrams showing procedures A and B described below.
The high-frequency signal transmitted from the transmitter 4 is distributed by the power distribution / combination circuit 3, and after the excitation phase is given by the phase shifter 2-n, it is radiated into the space from the element antenna 1-n. The radiated signal is received by the pickup antenna 6 and detected by the detection circuit 7.
Therefore, a change in the received power when the excitation phase of a certain element antenna is rotated 360 degrees by the phase shifter control circuit 5 is detected by the detection circuit 7, and further this change in received power is calculated by the element electric field calculation circuit 8. By processing, the element electric field amplitude and phase of the element antenna are obtained. Further, by repeating this procedure for all element antennas, the element electric field amplitudes and phases of all element antennas are obtained. This series of measurement procedures is referred to as procedure A.
The initial element electric field phase φ0, n of all element antennas measured by the above procedure A during the initial configuration of the phased array antenna is stored in the initial phase storage circuit 9, and subsequently measured by the above procedure A during the phased array antenna operation. The element electric field phases φ 1, n of all the element antennas are stored in the phase storage circuit 10. Both of the stored phases have different values due to a change in radiation characteristics during antenna operation. In order to calibrate the change in characteristics, the difference phase φ2, n of each element antenna is calculated by the difference phase calculation circuit 11 from both phases. Ask. By substituting the obtained differential phase into equation (2), the phase plane φs of the optimum desired function is obtained by the phase plane arithmetic circuit 12. From the obtained phase plane φs and the position of each element antenna, a correction phase to be given to each element antenna is obtained by the correction phase calculation circuit 13 according to equation (3). The correction phase of each element antenna thus obtained is assumed to be φc, n. The obtained correction phase φc, n and the initial excitation phase Φ0, n given to each phase shifter 2-n in the initial configuration of the phased array antenna stored in the initial excitation phase storage circuit 15 are substituted into the equation (4). Then, the excitation phase Φ1, n newly given to each phase shifter 2-n is obtained by the excitation phase calculation circuit 14. This series of procedures is referred to as procedure B.

  As described above, when mechanical deformation such as rotation or distortion occurs on the array antenna opening surface during operation of the phased array antenna, the element electric field phases φ0, n and φ1, n have different values. . At this time, when the signal-to-noise ratio of the detection system is large, the distribution of the differential phase φ2, n obtained from the element electric field phases φ0, n and φ1, n is as shown in FIG. The distribution is close to a phase distribution representing a change in optical path length due to mechanical deformation of the surface. Here, in FIG. 4, the horizontal axis represents the position of each element antenna 1-n on the array antenna opening surface, the vertical axis represents the differential phase φ2, n of each element antenna, and the straight line in the figure represents the array antenna opening surface. 2 respectively show phase distributions indicating changes in the optical path length due to mechanical deformation of (herein, indicating axial rotation of the aperture surface). Therefore, applying the excitation phase Φ1, n obtained by the procedure B to each phase shifter 2-n electrically corrects the change in the optical path length due to the mechanical deformation of the array antenna opening surface. It becomes possible to calibrate the radiation characteristic of the antenna to the radiation characteristic in the initial configuration of the array antenna.

  However, when the signal-to-noise ratio of the detection system is small, the element electric field phases φ0, n and φ1, n obtained by the procedure A include a large error. At this time, the distribution of the differential phase φ2, n is as shown in FIG. 5, which is significantly different from the phase distribution indicating the change in the optical path length due to the mechanical deformation of the array antenna aperture. Here, FIG. 5 shows the same axes and values as in FIG. 4, and further shows the phase plane φs. In the conventional technique, since a new excitation phase obtained from a correction phase including such a large error is given to each phase shifter, the antenna pattern changes greatly from the initial configuration. The gain is greatly reduced.

In the present invention, in order to optimize the differential phase φ2, n to the phase plane φs of the desired function, a function (in this case, each function representing the change in the optical path length due to mechanical deformation of the array antenna aperture is used as the desired function. By adopting a linear function with respect to the element antenna position, the error due to noise is a random error in the above phase plane φs obtained by the equation (2), and therefore due to mechanical deformation of the array antenna aperture surface. The phase plane is the same as the phase distribution indicating the change in the optical path length. The excitation phase Φ1, n obtained from the phase plane φs thus obtained becomes an excitation phase having the same phase, and the excitation phase Φ1, n is given to each phase shifter, whereby the initial configuration of the antenna pattern after calibration is obtained. The change from time can be reduced, and as a result, the amount of decrease in antenna gain can be reduced.
Accordingly, when the excitation phase Φ1, n obtained by the procedure B is given to each phase shifter 2-n, the signal-to-noise ratio of the detection system is small, and the measurement by the procedure A cannot be performed sufficiently. However, there is an effect that the radiation characteristic can be calibrated so as to reduce the amount of decrease in antenna gain as compared with the prior art.

  In FIG. 1, the transmission / reception relationship between the element antenna 1-n and the pickup antenna 6 is switched, and the transmitter 4 is connected to the pickup antenna 6 and transmitted from the transmitter 4 as shown in FIG. A high-frequency signal is radiated from the pickup antenna 6 into the space, the radiated signal is received by the element antenna 1-n, and an appropriate excitation phase is given by the phase shifter 2-n. Alternatively, the received power may be detected by the detection circuit 7.

Embodiment 2. FIG.
In the first embodiment, a linear function is adopted as a desired function with respect to each element antenna position so that the phase plane φs becomes a phase plane similar to a phase distribution indicating a change in optical path length due to rotational deformation of the array antenna aperture. did.
In the second embodiment, a quadratic function with respect to each element antenna position is used as a desired function so that the phase plane φs becomes a phase plane similar to a phase distribution indicating a change in optical path length due to thermal distortion deformation of the array antenna aperture. adopt. Therefore, in the second embodiment, the same effect as in the first embodiment can be obtained even when thermal distortion deformation occurs in the array antenna opening surface.

Embodiment 3 FIG.
In the third embodiment, a sine function relating to each element antenna position is adopted as a desired function so that the phase plane φs becomes a phase plane similar to a phase distribution indicating a change in optical path length due to wave-like deformation of the array antenna aperture. Therefore, in the third embodiment, the same effect as in the first embodiment can be obtained even when a wave-like deformation occurs in the array antenna opening surface.

Embodiment 4 FIG.
In the fourth embodiment, a function represented by the sum of a first-order function, a second-order function, and a sine function related to each element antenna position is adopted as a desired function. Therefore, in the fourth embodiment, the same effect as in the first embodiment can be obtained even when axial rotation, distortion deformation, and wave-like deformation occur simultaneously on the array antenna opening surface as shown in the above embodiment. .

Embodiment 5 FIG.
FIG. 7 is a diagram showing a configuration of an antenna apparatus according to Embodiment 5 of the present invention. Here, the case where it is applied to FIG. 1 exemplified in Embodiment 1 will be described as an example. In FIG. 7, the same or corresponding parts as those in the first embodiment are denoted by the same reference numerals and the description thereof is omitted. In the fifth embodiment, the reflecting mirror 16 is installed facing the phased array antenna to constitute an array-fed reflecting mirror antenna.
In the fifth embodiment configured as described above, the high-frequency signal transmitted from the transmitter 4 is distributed by the power distribution / combination circuit 3, and after the excitation phase is given by the phase shifter 2-n, the element antenna 1 -N radiates into space and reflects the signal emitted by the reflector 16; The signal reflected by the reflecting mirror 16 is received by the pickup antenna 6 and detected by the detection circuit 7.
Therefore, in the fifth embodiment, the same effect as in the first embodiment can be obtained even when the positional relationship between the phased array antenna and the reflecting mirror changes and the antenna radiation characteristics change.

  In FIG. 7, the relationship between transmission and reception of the element antenna 1-n and the pickup antenna 6 is switched. For example, as shown in FIG. 8, the transmitter 4 is connected to the pickup antenna 6 and transmitted from the transmitter 4. A high frequency signal is radiated from the pickup antenna 6 into the space, and the signal radiated by the reflecting mirror 16 is reflected. The signals reflected by the reflecting mirror 16 are respectively received by the element antenna 1-n, given an appropriate excitation phase by the phase shifter 2-n, synthesized by the power distribution and synthesis circuit 3, and received power by the detection circuit 7. May be detected.

Embodiment 6 FIG.
FIG. 9 is a diagram showing the configuration of the antenna device according to the sixth embodiment of the present invention. Here, the case where it is applied to FIG. 1 exemplified in Embodiment 1 will be described as an example. In FIG. 9, the same or corresponding parts as those in the first embodiment are denoted by the same reference numerals, and description thereof is omitted.
In the sixth embodiment, the phased array antenna, the receiving antenna 17, and the receiver 18 are mounted on the moving body, and the other means described in the first embodiment, the transmitting antenna 19, and the transmitter 20 are mounted. , Is provided in a fixed station.

In the sixth embodiment configured as described above, the excitation phase Φ1, n obtained by the excitation phase calculation circuit 14 becomes a high-frequency signal by the transmitter 20 and is radiated into the space by the transmission antenna 19. The radiated signal is received by the receiving antenna 17 and received by the receiver 18. The received excitation phase Φ1, n is given to the phase shifter 2-n.
Therefore, for example, when the moving body is a geostationary satellite and the fixed station is an earth station, the first embodiment also applies to the case where the antenna radiation characteristic changes due to a slight change in the orbit of the geostationary satellite from the original orbit. The same effect can be obtained.

  In FIG. 9, the transmission and reception relationships of the element antenna 1-n and the pickup antenna 6 are switched, and the transmitter 4 is connected to the pickup antenna 6 and transmitted from the transmitter 4 as shown in FIG. A high frequency signal is radiated from the pickup antenna 6 into the space, the radiated signal is received by the element antenna 1-n, and an appropriate excitation phase is given by the phase shifter 2-n. Alternatively, the received power may be detected by the detection circuit 7.

Embodiment 7 FIG.
In the above-described embodiment, the equation (2) is used as means for obtaining the phase plane φs that minimizes the difference between the differential phase φ2, n and the phase plane of the desired function in the phase plane arithmetic circuit 12. However, since there is a 360-degree uncertainty in the electric field phase of each element antenna obtained by the procedure A, the distribution of the differential phase φ2, n as shown in FIG. There is a case where the distribution is greatly different from the phase distribution indicating the change of the optical path length due to the deformation.

  Here, FIG. 11 shows the same axes and values as in FIG. 4, and further shows the phase plane φs. For this reason, the phase plane φs obtained using the equation (2) has a distribution greatly different from the phase distribution indicating the change in the optical path length due to the mechanical deformation of the array antenna aperture, and the above effects cannot be obtained. There is. This phase uncertainty can be taken into account by treating the phase with complex numbers. That is, the same effect can be obtained by obtaining the phase plane φs that minimizes the expression (5) by, for example, the conjugate gradient method.

（５）

(5)

  Needless to say, the present invention is not limited to the above-described embodiment, and includes possible combinations thereof.

BRIEF DESCRIPTION OF THE DRAWINGS It is structure explanatory drawing which shows the antenna apparatus concerning Embodiment 1 of this invention. It is a figure which shows the procedure of the procedure A of this invention. It is a figure which shows the procedure of the procedure B of this invention. It is explanatory drawing which showed the phase distribution of a difference phase in case a signal-to-noise ratio is large. It is explanatory drawing which showed the phase distribution of a difference phase in case a signal-to-noise ratio is small. It is a structure explanatory drawing which shows the other structural example of the antenna apparatus concerning Embodiment 1 of this invention. It is a structure explanatory drawing which shows the antenna apparatus concerning Embodiment 5 of this invention. It is a structure explanatory drawing which shows the other structural example of the antenna apparatus concerning Embodiment 5 of this invention. It is composition explanatory drawing which shows the antenna apparatus concerning Embodiment 6 of this invention. It is structure explanatory drawing which shows the other structural example of the antenna apparatus concerning Embodiment 6 of this invention. It is explanatory drawing which showed the influence by the uncertainty of 360 degree | times of an electric field phase.

Explanation of symbols

  1-1 to 1-N element antenna, 2-1 to 2-N phase shifter, 3 power distribution and synthesis circuit, 4 transmitter, 5 phase shifter control circuit, 6 pickup antenna, 7 detector circuit, 8 element electric field calculation Circuit, 9 initial phase storage circuit, 10 phase storage circuit, 11 differential phase calculation circuit, 12 phase plane calculation circuit, 13 correction phase calculation circuit, 14 excitation phase calculation circuit, 15 initial excitation phase storage circuit, 16 reflector, 17 reception Antenna, 18 receiver, 19 Transmitting antenna, 20 Transmitter.

Claims (7)

A plurality of element antennas, a phase shifter connected to each of the element antennas, a phase shifter control circuit for controlling a set phase of each of the phase shifters, a power distribution and synthesis circuit connected to each of the phase shifters, A phased array antenna having detection means connected to the power distribution and synthesis circuit; and when the phased array antenna receives a radio wave for calibration of radiation characteristics, the set phase of each phase shifter is sequentially set to 360 degrees. Based on a change in received power output from the detection means when rotated, means for calculating a set phase of an element antenna connected to each corresponding phase shifter, and the means calculated by the means twice Stores the reference value and comparison value for calibration of the radiation characteristic change of the phased array antenna of the set phase of each phase shifter, and calculates the difference phase between the reference value and the comparison value Calculating means, calculating a phase plane of a desired function from the differential phase by a predetermined optimization, calculating a correction phase to be set for each element antenna based on the calculated phase plane, and the correction phase And an excitation phase calculation circuit that calculates an excitation phase to be applied to each element antenna based on an initial excitation phase preset in each phase shifter and outputs the calculated phase to the phase shifter control circuit. An antenna device. A plurality of element antennas, a phase shifter connected to each of the element antennas, a phase shifter control circuit for controlling a set phase of each of the phase shifters, a power distribution and synthesis circuit connected to each of the phase shifters, A phased array antenna having a transmission means connected to the power distribution and synthesis circuit; a pickup antenna installed opposite to the phased array antenna so as to receive radio waves from the phased array antenna; and connected to the pickup antenna Based on the change in received power at the pickup antenna output from the detection means when the set phase of each of the phase shifters is sequentially rotated 360 degrees respectively Means for calculating the set phase of the element antenna connected to the device, and the set position of each phase shifter calculated by the means twice. A reference value and a comparison value for calibration of radiation characteristic change of the phased array antenna are stored, a difference phase calculation means for calculating a difference phase between the reference value and the comparison value, and a desired optimization by a predetermined optimization from the difference phase A correction phase calculating means for calculating a phase plane of the function and calculating a correction phase to be set for each element antenna based on the calculated phase plane; and an initial excitation phase preset for each of the correction phase and each phase shifter And an excitation phase calculation circuit that calculates an excitation phase to be applied to each element antenna based on the above and outputs the excitation phase to the phase shifter control circuit. 3. The antenna apparatus according to claim 2, further comprising a transmitting means and a receiving means for spatially transmitting the output of the excitation phase calculation circuit to the phase shifter control circuit. 4. The antenna apparatus according to claim 1, further comprising a reflecting mirror disposed so as to be opposed to the phased array antenna so as to be able to receive radio waves from the phased array antenna. 5. The antenna device according to claim 1, wherein the phase plane of the desired function is a phase plane represented by a linear function related to the position coordinates of each of the element antennas. 5. The antenna device according to claim 1, wherein the phase plane of the desired function is a phase plane represented by a quadratic function related to the position coordinates of each element antenna. The antenna device according to any one of claims 1 to 4, wherein the phase plane of the desired function is a phase plane represented by a sine function relating to the position coordinates of each element antenna.

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