Array antenna calibration device and array antenna calibration program

Abstract

To isolate the cause of abnormality, such as whether a wrong solution is selected or not, whether the abnormal operation of each antenna element is performed or not, and whether or not an S / N at the time of measurement is low, as the amplitude and phase of a relative radiated electric field of each antenna element, without the large cost and know-how when each antenna element is calibrated so as to equalize the amplitude characteristics and the phase characteristics of the radiated electric field of each antenna element using the REV method (element electric field vector rotation method).SOLUTION: An array antenna calibration device includes a calibration accuracy evaluation part 24 for evaluating the calibration accuracy across all antenna elements 11-1 to 11-N based on the magnitude of the difference between a summation vector across all antenna elements 11-1 to 11-N and an initial synthesized radiated electric field vector of all antenna elements 11-1 to 11-N regarding a relative radiated electric field vector of each antenna element 11-n.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a technique for calibrating each antenna element using the REV method (Rotating element Electric field Vector method) so as to align the amplitude and phase characteristics of the radiated electric field of each antenna element. [Background technology]

[0002] Patent Documents 1 and 2, Non-Patent Document 1, and the like disclose techniques for calibrating each antenna element using the REV method so as to align the amplitude characteristics and phase characteristics of the radiated electric field of each antenna element.

[0003] First, the amplitude of the combined radiated electric field of all antenna elements is measured while rotating the phase of the radiated electric field of each antenna element from the phase of the initial radiated electric field. Next, based on the amplitude of the combined radiated electric field of all antenna elements, the amplitude and phase of the relative radiated electric field of each antenna element are calculated with reference to the amplitude and phase of the initial combined radiated electric field of all antenna elements. Next, based on the amplitude and phase of the relative radiated electric field of each antenna element, each antenna element is calibrated so that the amplitude characteristics and phase characteristics of the radiated electric field of each antenna element are aligned.

[0004] In this way, the amplitude and phase characteristics of the radiated electric field of each element of the phased array antenna can be calibrated by simply measuring the amplitude of the radiated electric field of all antenna elements, without measuring the phase of the radiated electric field of all antenna elements. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Special Publication No. 03-038548 [Patent Document 2] Japanese Patent Application Laid-Open No. 2001-201526 [Non-patent literature]

[0006] [Non-Patent Document 1] Kiyoji Mano and Takashi Katagi, "Method for Measuring Element Amplitude and Phase of Phased Array Antennas - Element Electric Field Vector Rotation Method," Transactions of the Institute of Electronics, Information and Communication Engineers, May 1982, Vol. B65, No. 5, pp. 555-560. Summary of the Invention [Problem to be solved by the invention]

[0007] Here, depending on whether the amplitude of the initial composite radiated electric field of all antenna elements excluding each antenna element is larger or smaller than the amplitude of the radiated electric field of each antenna element, one of two solutions (K1 solution and K2 solution) must be selected as the amplitude and phase of the relative radiated electric field of each antenna element.

[0008] In order to determine whether the correct solution has been selected for the amplitude and phase of the relative radiated electric field of each antenna element, it is necessary to check the calibration coefficients of each antenna element, the radiation patterns of all antenna elements, or the pulse extraction waveforms of all antenna elements.

[0009] Furthermore, simply checking the calibration coefficients of each antenna element, the radiation patterns of all antenna elements, or the extracted pulse waveforms of all antenna elements makes it difficult to determine the cause of the abnormality, such as whether an incorrect solution was selected for the amplitude and phase of the relative radiated electric field of each antenna element, whether there was abnormal operation of each antenna element, or whether the S / N ratio was low during measurement.

[0010] Moreover, checking the calibration coefficients of each antenna element, the radiation patterns of all antenna elements, or the extracted pulse waveforms of all antenna elements requires a great deal of cost and know-how.

[0011] Therefore, in order to solve the above-mentioned problems, the present disclosure aims to identify the cause of the abnormality without significant cost or know-how, such as whether an incorrect solution was selected for the amplitude and phase of the relative radiated electric field of each antenna element, whether there was abnormal operation of each antenna element, or whether the S / N ratio was low during measurement, when calibrating each antenna element using the REV method (element electric field vector rotation method) to align the amplitude characteristics and phase characteristics of the radiated electric field of each antenna element. [Means for solving the problem]

[0012] To solve the above problem, the calibration accuracy of all antenna elements is evaluated based on the magnitude of the difference between the sum vector of the relative radiation electric field vectors of each antenna element across all antenna elements and the initial composite radiation electric field vector of all antenna elements. When the difference is large, there is a high possibility that an incorrect solution has been selected as the amplitude and phase of the relative radiation electric field of each antenna element.

[0013] Specifically, the present disclosure provides an array antenna calibration device comprising: a radiated electric field measurement unit that measures the amplitude of a composite radiated electric field of all elements of the array antenna while rotating the phase of the radiated electric field of each element of the array antenna from the phase of an initial radiated electric field; an amplitude and phase calculation unit that calculates the amplitude and phase of a relative radiated electric field of each element based on the amplitude of the composite radiated electric field of all elements and with reference to the amplitude and phase of the initial composite radiated electric field of all elements; an amplitude and phase calibration unit that calibrates each element based on the amplitude and phase of the relative radiated electric field of each element so as to align the amplitude characteristics and phase characteristics of the radiated electric field of each element; and a calibration accuracy evaluation unit that evaluates the calibration accuracy of all elements based on the magnitude of the difference between a sum vector across all elements for the relative radiated electric field vector of each element, which is composed of the amplitude and phase of the relative radiated electric field of each element, and an initial composite radiated electric field vector of all elements, which is composed of the amplitude and phase of the initial composite radiated electric field of all elements.

[0014] The present disclosure also provides an array antenna calibration program that causes a computer to sequentially execute the following steps: a radiation field measurement step of measuring the amplitude of a composite radiation field of all elements of the array antenna while rotating the phase of the radiation field of each element from the phase of an initial radiation field; an amplitude and phase calculation step of calculating the amplitude and phase of a relative radiation field of each element based on the amplitude of the composite radiation field of all elements and with reference to the amplitude and phase of the initial composite radiation field of all elements; an amplitude and phase calibration step of calibrating each element based on the amplitude and phase of the relative radiation field of each element so as to align the amplitude characteristics and phase characteristics of the radiation field of each element; and a calibration accuracy evaluation step of evaluating the calibration accuracy of all elements based on the magnitude of the difference between a sum vector across all elements regarding the relative radiation field vector of each element, which is composed of the amplitude and phase of the relative radiation field of each element, and an initial composite radiation field vector of all elements, which is composed of the amplitude and phase of the initial composite radiation field of all elements.

[0015] These configurations make it possible to investigate the cause of an anomaly, such as selecting an incorrect solution for the amplitude and phase of the relative radiated electric field of each antenna element, without significant cost or know-how. In other words, it is sufficient to simply calculate the difference without checking the calibration coefficients of each antenna element, the radiation patterns of all antenna elements, or the extracted pulse waveforms of all antenna elements.

[0016] The present disclosure also provides an array antenna calibration device, characterized in that the calibration accuracy evaluation unit evaluates the calibration accuracy of each element based on the magnitude of the coefficient of determination between the measurement result of the amplitude of the composite radiation electric field of all the elements relative to the rotation phase of the radiation electric field from the phase of the initial radiation electric field of each element and a sine function or cosine function having an arbitrary amplitude and phase.

[0017] With this configuration, it is possible to investigate the cause of an abnormality without significant cost or know-how, such as whether there was an abnormal operation of each antenna element, whether the S / N ratio during measurement was low, etc. In other words, it is only necessary to calculate the coefficient of determination without checking the calibration coefficient of each antenna element, the radiation patterns of all antenna elements, or the extracted pulse waveforms of all antenna elements.

[0018] The present disclosure also provides an array antenna calibration device, characterized in that the calibration accuracy evaluation unit determines abnormal operation of each of the elements when the coefficient of determination is smaller than a predetermined value, determines normal operation of each of the elements and a spurious solution of the amplitude-phase calculation unit when the coefficient of determination is larger than the predetermined value but the difference is larger than the predetermined value, and determines normal operation of each of the elements and a normal solution of the amplitude-phase calculation unit when the coefficient of determination is larger than the predetermined value and the difference is smaller than the predetermined value.

[0019] According to this configuration, by using the difference and the coefficient of determination in combination, it is possible to determine the cause of the abnormality without significant cost or know-how, whether it is a problem with the REV method algorithm or a problem with the hardware of the array antenna transceiver device. In other words, it is sufficient to simply calculate the difference and the coefficient of determination without checking the calibration coefficients of each antenna element, the radiation patterns of all antenna elements, or the extracted pulse waveforms of all antenna elements.

[0020] To solve the above problem, the calibration accuracy of each antenna element is evaluated based on the magnitude of the coefficient of determination between the measurement result of the amplitude of the combined radiated electric field of all antenna elements relative to the rotation phase of the radiated electric field from the initial radiated electric field phase of each antenna element and a sine function or a cosine function. If the coefficient of determination is small, there is a high possibility that each antenna element may have been operating abnormally or the S / N ratio during measurement may have been low.

[0021] Specifically, the present disclosure provides an array antenna calibration device comprising: a radiation field measurement unit that measures the amplitude of a composite radiation field of all elements of the array antenna while rotating the phase of the radiation field of each element of the array antenna from the phase of an initial radiation field; an amplitude / phase calculation unit that calculates the amplitude and phase of a relative radiation field of each element based on the amplitude of the composite radiation field of all elements and with reference to the amplitude and phase of the initial composite radiation field of all elements; an amplitude / phase calibration unit that calibrates each element based on the amplitude and phase of the relative radiation field of each element so as to align the amplitude characteristics and phase characteristics of the radiation field of each element; and a calibration accuracy evaluation unit that evaluates the calibration accuracy of each element based on the magnitude of the coefficient of determination between the measurement result of the amplitude of the composite radiation field of all elements with respect to the rotation phase of the radiation field from the phase of the initial radiation field of each element and a sine function or cosine function having an arbitrary amplitude and phase.

[0022] With this configuration, it is possible to investigate the cause of an abnormality without significant cost or know-how, such as whether there was an abnormal operation of each antenna element, whether the S / N ratio during measurement was low, etc. In other words, it is only necessary to calculate the coefficient of determination without checking the calibration coefficient of each antenna element, the radiation patterns of all antenna elements, or the extracted pulse waveforms of all antenna elements. [Effects of the Invention]

[0023] In this way, the present disclosure uses the REV method (element electric field vector rotation method) to calibrate each antenna element so as to align the amplitude and phase characteristics of the radiated electric field of each antenna element, and can identify the cause of the abnormality without significant cost or know-how, such as whether an incorrect solution was selected for the amplitude and phase of the relative radiated electric field of each antenna element, whether there was abnormal operation of each antenna element, or whether the S / N ratio during measurement was low. [Brief explanation of the drawings]

[0024] [Figure 1] FIG. 1 is a diagram illustrating the configuration of an array antenna system according to the present disclosure. [Figure 2] FIG. 10 is a diagram showing the procedure of the array antenna calibration process of the present disclosure. [Figure 3] FIG. 1 is a diagram illustrating an overview of the array antenna calibration process of the present disclosure. [Figure 4] FIG. 10 is a diagram illustrating details of the selection process of the K1 solution or the K2 solution according to the present disclosure. [Figure 5] FIG. 10 is a diagram showing the procedure of the calibration accuracy evaluation process of the present disclosure. [Figure 6] FIG. 10 is a diagram showing an overview of a first calibration accuracy evaluation process of the present disclosure. [Figure 7] FIG. 10 is a diagram showing an overview of a second calibration accuracy evaluation process of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0025]

[0023] The following embodiments of the present disclosure will be described with reference to the accompanying drawings. The embodiments described below are examples of implementation of the present disclosure, and the present disclosure is not limited to the following embodiments.

[0026] (Array antenna calibration process of the present disclosure) The configuration of the array antenna system of the present disclosure is shown in Fig. 1. The array antenna system A includes an array antenna transceiver 1 and an array antenna calibration device 2. The array antenna transceiver 1 includes antenna elements 11-n (n = 1 to N), attenuators 12-n (n = 1 to N), phase shifters 13-n (n = 1 to N), a divider / combiner 14, a transceiver unit 15, and a control unit 16, and can be an all-analog system, an all-digital system, or an analog / digital hybrid system. The array antenna calibration device 2 includes a radiated electric field measurement unit 21, an amplitude / phase calculation unit 22, an amplitude / phase calibration unit 23, and a calibration accuracy evaluation unit 24, and can be implemented by installing the array antenna calibration program shown in Fig. 2 and the calibration accuracy evaluation program shown in Fig. 5 on a computer.

[0027] The procedure for the array antenna calibration process of the present disclosure is shown in Figure 2. An overview of the array antenna calibration process of the present disclosure is shown in Figure 3. Details of the selection process of the K1 solution or K2 solution of the present disclosure are shown in Figure 4.

[0028] The radiated electric field measuring unit 21 measures the amplitude of the combined radiated electric field of all the antenna elements 11-1 to 11-N while rotating the phase of the radiated electric field of each antenna element 11-n from the phase of the initial radiated electric field using each phase shifter 12-n (step S1). In the first stage of FIG. 3, the initial radiated electric field vector E 0、n The power of the initial combined radiation field of all antenna elements 11-1 to 11-N is |E0| 2 (initial composite radiated electric field vector E0) is measured, and the phase Δ m、n With the rotation of (m=1 to M), the power |E m、n '| 2 (Composite radiation electric field vector E m、n ') is measured.

[0029] In the first stage of FIG. 3, since there are variations in the circuit characteristics of each antenna element 11-n, the amplitude |E 0、n | and phase φ 0、n are not aligned, and the initial radiation electric field vector E 0、n The lengths and directions of the

[0030] The amplitude and phase calculation unit 22 calculates the amplitude and phase of the relative radiation field of each antenna element 11-n based on the amplitude and phase of the initial composite radiation field of all the antenna elements 11-1 to 11-N (step S2). In the second stage of FIG. 3, the phase Δ of the radiation field of each antenna element 11-n is calculated. m、n The power ratio of the combined radiated electric field of all antenna elements 11-1 to 11-N |E m、n '| 2 / |E0| 2 In the third stage of FIG. 3, the amplitude ratio k of the relative radiation electric field of each antenna element 11-n is calculated based on the amplitude |E0| and phase φ0 of the initial composite radiation electric field of all antenna elements 11-1 to 11-N. n =|E 0、n | / |E0| and phase X n =φ 0、n-φ0 is calculated. Details of the second and third stages of FIG.

[0031] The amplitude and phase calibration unit 23 calibrates each antenna element 11-n using the control unit 16 based on the amplitude and phase of the relative radiated electric field of each antenna element 11-n so as to align the amplitude and phase characteristics of the radiated electric field of each antenna element 11-n (step S3). In the fourth stage of FIG. 3, the amplitude |E 0、n ”| and phase φ 0、n The calibration coefficients (correction amounts of the amplitude and phase of the radiated electric field) of each attenuator 12-n and each phase shifter 13-n are calculated so that " are the same.

[0032] The radiated electric field measuring unit 21, the amplitude / phase calculating unit 22, and the amplitude / phase calibrating unit 23 repeat steps S1 to S3 for all of the antenna elements 11-1 to 11-N (step S4).

[0033] In the fourth row of FIG. 3, even if there are variations in the circuit characteristics of each antenna element 11-n, the amplitude |E 0、n ”| and phase φ 0、n ” are aligned, and the radiated electric field vector E 0、n " are aligned in length and direction.

[0034] In this way, the phase arg(E m、n Without measuring the power |E m、n '| 2 By simply measuring the amplitude and phase characteristics of the radiated electric field of each antenna element 11-n of the phased array antenna, it is possible to calibrate the amplitude and phase characteristics of the radiated electric field of each antenna element 11-n of the phased array antenna.

[0035] In the first stage of FIG. 4, the amplitude |Y n |=|E 0、1 +···+E 0、N -E 0、n| is the amplitude |E of the radiated electric field of each antenna element 11-n m、n Therefore, the relative amplitude ratio k of the radiation electric field of each antenna element 11-n is n =|E 0、n | / |E0| and phase X n =φ 0、n As -φ0, it is necessary to select the K1 solution.

[0036] Here, the relative amplitude ratio k of the radiation electric field of each antenna element 11-n is n is calculated as in Equations 1 and 2, and the phase X of the relative radiation field of each antenna element 11-n is n is calculated as in Equations 1 and 3. Then, Q in Equation 1 n、max and Q n、min is |E m、n '| 2 / |E0| 2 are the maximum and minimum values ​​of Δ m_max、n is |E m、n '| 2 / |E0| 2 Δ gives the maximum value of m、n (In the second row of Figure 3, |E m、n '| 2 / |E0| 2 and Δ m、n The relationship between is approximated by a sine or cosine function.

number

number

number

[0037] In the second stage of FIG. 4, the amplitude |Y n |=|E 0、1 +···+E 0、N -E 0、n | is the amplitude |E of the radiated electric field of each antenna element 11-n m、nTherefore, the relative amplitude ratio k of the radiation electric field of each antenna element 11-n is n =|E 0、n | / |E0| and phase X n =φ 0、n As -φ0, the K2 solution must be selected.

[0038] Here, the relative amplitude ratio k of the radiation electric field of each antenna element 11-n is n is calculated as in Equations 4 and 5, and the phase X of the relative radiation field of each antenna element 11-n is n is calculated as in Equations 4 and 6. Then, Q in Equation 4 n、max and Q n、min is |E m、n '| 2 / |E0| 2 are the maximum and minimum values ​​of Δ m_max、n is |E m、n '| 2 / |E0| 2 Δ gives the maximum value of m、n (In the second row of Figure 3, |E m、n '| 2 / |E0| 2 and Δ m、n The relationship between is approximated by a sine or cosine function.

number

number

number

[0039] However, the amplitude |Y n |=|E 0、1 +···+E 0、N -E 0、n is the amplitude |E of the radiated electric field of each antenna element 11-n. m、n Therefore, it is not obvious whether the amplitude ratio k of the relative radiated electric field of each antenna element 11-n is larger or smaller than |. n =|E0、n | / |E0| and phase X n =φ 0、n It is not obvious which of the K1 solution and the K2 solution should be selected as -φ0, so the following first to third selection methods are performed.

[0040] In the first selection method, multiple different states are set for the amplitude |E0| and phase φ0 (mainly phase φ0) of the initial composite radiation electric field of all antenna elements 11-1 to 11-N, and then K1 solutions and K2 solutions are calculated in the multiple different states, and a solution that has the same meaning in the multiple different states is selected.

[0041] In the second selection method, the power |E m、n '| 2 In addition to measuring the phase arg(E m、n After measuring the phase Δ m、n As the antenna element 11-1 rotates, the phase arg(E m、n When ') does not change by more than 180°, the K1 solution is selected.

[0042] In the third selection method, the amplitude |Y n is the amplitude |E of the radiated electric field of each antenna element 11-n. m、n The phase φ of the initial radiation field of each antenna element 11-n is set to be always larger than | 0、n After setting, select the K1 solution.

[0043] In addition, in formulas 1 and 4, Q n、min Since is 0 or negative, r n 2 When the calibration coefficient of each antenna element 11-n is abnormal (YES in step S5), the amplitude-phase calibrator 23 calibrates the phase φ of the initial radiation electric field of each antenna element 11-n.0、n (step S6), the radiated electric field measurement unit 21, the amplitude / phase calculation unit 22, and the amplitude / phase calibration unit 23 re-execute the REV method. On the other hand, if the calibration coefficients of each antenna element 11-n are normal (NO in step S5), the amplitude / phase calibration unit 23 does not execute step S6, and the radiated electric field measurement unit 21, the amplitude / phase calculation unit 22, and the amplitude / phase calibration unit 23 end the REV method.

[0044] (Calibration accuracy evaluation process of the present disclosure) The procedure of the calibration accuracy evaluation process of the present disclosure is shown in Fig. 5. An outline of the first calibration accuracy evaluation process of the present disclosure is shown in Fig. 6. An outline of the second calibration accuracy evaluation process of the present disclosure is shown in Fig. 7.

[0045] As a first calibration accuracy evaluation process, the calibration accuracy evaluation unit 24 evaluates the calibration accuracy across all antenna elements 11-1 to 11-N based on the magnitude of the difference between the sum vector across all antenna elements 11-1 to 11-N, which is related to the relative radiation electric field vector of each antenna element 11-n and is composed of the amplitude and phase of the relative radiation electric field of each antenna element 11-n, and the initial composite radiation electric field vector of all antenna elements 11-1 to 11-N, which is composed of the amplitude and phase of the initial composite radiation electric field of all antenna elements 11-1 to 11-N (step S11).

[0046] In the first stage of FIG. 6, the phase X of the relative radiation field of each antenna element 11-n is n =φ 0、n -φ0 are not uniform (for example, there is variation in the circuit characteristics of each antenna element 11-n). Therefore, the amplitude |Y n |=|E 0、1 +···+E 0、N -E 0、n is the amplitude |E of the radiated electric field of each antenna element 11-n. m、n Therefore, the probability that the K2 solution occurs is high. In the first to third selection methods described above, the probability that the K2 solution is not selected and the K1 solution is erroneously selected is high.

[0047] The sum vector of all antenna elements 11-1 to 11-N with respect to the relative radiation electric field vector of each antenna element 11-n can be expressed as a complex number as follows: Σ|E 0、n | / |E0|×exp(j(φ 0、n -φ0))=Σk n exp(jX n ) Theoretically, under the condition that there is no error at all, the initial composite radiation electric field vector of all antenna elements 11-1 to 11-N is expressed as a complex number as |E0| / |E0|×exp(j(φ0-φ0))=1+0j. k n and X n When an incorrect solution is selected as Σk n exp(jX n )≠1.

[0048] In the second stage of FIG. 6, the phase X of the relative radiation field of each antenna element 11-n is n =φ 0、n Therefore, the amplitude |Y n |=|E 0、1 +···+E 0、N -E 0、n is the amplitude |E of the radiated electric field of each antenna element 11-n. m、n Therefore, the probability that the K2 solution occurs is low. In the first to third selection methods described above, the probability that the K2 solution is not selected and the K1 solution is correctly selected is high.

[0049] The sum vector of all antenna elements 11-1 to 11-N with respect to the relative radiation electric field vector of each antenna element 11-n can be expressed as a complex number as follows: Σ|E 0、n | / |E0|×exp(j(φ 0、n -φ0))=Σk n exp(jX n ) Theoretically, under the condition that there is no error at all, the initial composite radiation electric field vector of all antenna elements 11-1 to 11-N is expressed as a complex number as |E0| / |E0|×exp(j(φ0-φ0))=1+0j. k n and X nWhen the correct solution is selected as Σk n exp(jX n )≒1.

[0050] In this way, the cause of an anomaly, such as the selection of an incorrect solution for the amplitude and phase of the relative radiation electric field of each antenna element 11-n, can be investigated without significant cost or know-how. In other words, the difference Σk n exp(jX n )-1. In Equations 1 and 4, Q n、min Since is 0 or negative, r n 2 Being ∞ or negative can also be a cause of anomalies.

[0051] As a second calibration accuracy evaluation process, the calibration accuracy evaluation unit 24 evaluates the calibration accuracy of each antenna element 11-n based on the magnitude of the coefficient of determination between the measurement result of the amplitude of the combined radiation electric field of all antenna elements 11-1 to 11-N relative to the rotation phase of the radiation electric field from the phase of the initial radiation electric field of each antenna element 11-n and a sine function or cosine function having an arbitrary amplitude and phase (step S12).

[0052] 7, each antenna element 11-n is operating abnormally or has a low S / N ratio during measurement. Therefore, the phase Δ m、n When the antenna element 11-1 rotates from the phase of the initial radiation field of 0° to 360° after one rotation, the power |E m、n '| 2 However, it does not match precisely with sine or cosine functions of arbitrary amplitude and phase.

[0053] The phase Δ of the radiated electric field of each antenna element 11-n m、n The power of the combined radiated electric field of all antenna elements 11-1 to 11-N is |E m、n '| 2However, |E m、n '| 2 =A+Bcos(Δ m、n -Δ m_max、n ) is approximated by the coefficient of determination R 2 is 0.852. In the approximation formula, A, B and Δ m_max、n However, since it cannot be calculated accurately, in Equations 1 to 6, Q n、max , Q n、min and Δ m_max、n is not calculated accurately, and k n and X n is not calculated accurately.

[0054] 7, there is no abnormal operation of each antenna element 11-n or the S / N ratio during measurement is high. Therefore, the phase Δ m、n When the antenna element 11-1 rotates from the phase of the initial radiation field of 0° to 360° after one rotation, the power |E m、n '| 2 corresponds accurately to a sine or cosine function with arbitrary amplitude and phase.

[0055] The phase Δ of the radiated electric field of each antenna element 11-n m、n The power of the combined radiated electric field of all antenna elements 11-1 to 11-N is |E m、n '| 2 However, |E m、n '| 2 =A+Bcos(Δ m、n -Δ m_max、n ) is approximated by the coefficient of determination R 2 is 0.997. In the approximation formula, A, B and Δ m_max、n is calculated accurately, so in Equations 1 to 6, Q n、max , Q n、min and Δ m_max、n is calculated exactly, and k n and X n is also calculated accurately.

[0056] In this way, the cause of the abnormality, such as whether there was an abnormal operation of each antenna element 11-n or whether the S / N ratio during measurement was low, can be investigated without a great deal of cost or know-how. In other words, the coefficient of determination R 2 The abnormal operation of each antenna element 11-n may be an abnormal operation of each phase shifter 13-n, an abnormal operation of each attenuator 12-n, or unnecessary electric field / magnetic field coupling from an adjacent antenna element 11-n to each antenna element 11-n.

[0057] Here, when there is an abnormal operation of each antenna element 11-n, or when the S / N ratio during measurement is low, the coefficient of determination R 2 Not only does the difference Σk n exp(jX n )-1 may be large. Therefore, the difference Σk n exp(jX n Based only on the fact that )-1 is large, it is not possible to determine whether an incorrect solution was selected for the amplitude and phase of the relative radiated electric field of each antenna element 11-n, whether there was an abnormal operation of each antenna element 11-n, or whether the S / N ratio during measurement was low. Therefore, the following process is executed.

[0058] The calibration accuracy evaluation unit 24 calculates the coefficient of determination R 2 When is smaller than the predetermined value (step S13, YES), the difference Σk n exp(jX n )-1, the radiated electric field measurement unit 21, the amplitude / phase calculation unit 22, and the amplitude / phase calibration unit 23 correct the abnormal operation of each antenna element 11-n or improve the S / N ratio during measurement, and then execute the REV method again (step S15).

[0059] The calibration accuracy evaluation unit 24 calculates the coefficient of determination R 2 Although is larger than the predetermined value (step S13, NO), the difference Σk nexp(jX n If )-1 is greater than the predetermined value (step S16, YES), the normal operation of each antenna element 11-n and the spurious solution of the amplitude / phase calculation unit 22 are determined (step S17). Then, the radiated electric field measurement unit 21, the amplitude / phase calculation unit 22, and the amplitude / phase calibration unit 23 correct the REV method and re-execute it (step S18).

[0060] The calibration accuracy evaluation unit 24 calculates the coefficient of determination R 2 is larger than the predetermined value (step S13, NO), and the difference Σk n exp(jX n If )-1 is smaller than the predetermined value (step S16, NO), it is determined whether each antenna element 11-n is operating normally and whether the amplitude / phase calculation unit 22 has a normal solution (step S19). Then, the radiated field measurement unit 21, the amplitude / phase calculation unit 22, and the amplitude / phase calibration unit 23 end the process without modifying the REV method (step S20).

[0061] In this way, the difference Σk n exp(jX n )-1 and the coefficient of determination R 2 By using this method in combination, it is possible to determine without much cost or know-how whether the cause of the abnormality is a problem with the REV method algorithm or a problem with the hardware of the array antenna transceiver 1. In other words, it is possible to calculate the difference Σk without checking the calibration coefficients of each antenna element 11-n, the radiation patterns of all antenna elements 11-1 to 11-N, or the extracted pulse waveforms of all antenna elements 11-1 to 11-N. n exp(jX n )-1 and the coefficient of determination R 2 It is only necessary to calculate [Industrial Applicability]

[0062] The array antenna calibration device and array antenna calibration program disclosed herein use the REV method to calibrate each antenna element so as to align the amplitude and phase characteristics of the radiated electric field of each antenna element, and can isolate the cause of an abnormality without significant cost or know-how. [Explanation of symbols]

[0063] A: Array antenna system 1: Array antenna transmitter / receiver 2: Array antenna calibration equipment 11-1, 11-2, 11-3, 11-N: Antenna elements 12-1, 12-2, 12-3, 12-N: Attenuators 13-1, 13-2, 13-3, 13-N: Phase shifter 14:Distributor / Synthesizer 15: Transmitter / receiver 16: Control unit 21: Radiation field measurement unit 22: Amplitude and phase calculation unit 23: Amplitude and phase calibration section 24: Calibration accuracy evaluation unit

Claims

1. A radiation electric field measurement unit that measures the amplitude of a composite radiation electric field of all elements of the array antenna while rotating the phase of the radiation electric field of each element of the array antenna from the phase of the initial radiation electric field using the REV method (element electric field vector rotation method); an amplitude / phase calculation unit that calculates the amplitude and phase of the relative radiation electric field of each of the elements based on the amplitude and phase of the initial composite radiation electric field of all the elements using the REV method, based on the amplitude of the composite radiation electric field of all the elements; an amplitude and phase calibration unit that calibrates each of the elements based on the amplitude and phase of the relative radiation electric field of each of the elements using the REV method so as to align the amplitude characteristics and phase characteristics of the radiation electric field of each of the elements; a calibration accuracy evaluation unit that evaluates the calibration accuracy of all elements to be lower as the difference between the total vector of all elements, which is related to the relative radiation electric field vector of each element and is composed of the amplitude and phase of the relative radiation electric field of each element, and the initial composite radiation electric field vector of all elements, which is composed of the amplitude and phase of the initial composite radiation electric field of all elements, is larger; An array antenna calibration device comprising:

2. The calibration accuracy evaluation unit evaluates the calibration accuracy of each element lower as the coefficient of determination between the measurement result of the amplitude of the composite radiation electric field of all the elements relative to the rotation phase of the radiation electric field from the phase of the initial radiation electric field of each element and a sine function or cosine function having an arbitrary amplitude and phase becomes smaller.

2. The array antenna calibration device according to claim 1, wherein:

3. The calibration accuracy evaluation unit determines that each of the elements is operating abnormally when the coefficient of determination is smaller than a predetermined value, determines that each of the elements is operating normally and that the amplitude / phase calculation unit has a spurious solution when the coefficient of determination is larger than the predetermined value but the difference is larger than the predetermined value, and determines that each of the elements is operating normally and that the amplitude / phase calculation unit has a normal solution when the coefficient of determination is larger than the predetermined value and the difference is smaller than the predetermined value.

3. The array antenna calibration device according to claim 2.

4. A radiation electric field measurement unit that measures the amplitude of a composite radiation electric field of all elements of the array antenna while rotating the phase of the radiation electric field of each element of the array antenna from the phase of the initial radiation electric field using the REV method (element electric field vector rotation method); an amplitude / phase calculation unit that calculates the amplitude and phase of the relative radiation electric field of each of the elements based on the amplitude and phase of the initial composite radiation electric field of all the elements using the REV method, based on the amplitude of the composite radiation electric field of all the elements; an amplitude and phase calibration unit that calibrates each of the elements based on the amplitude and phase of the relative radiation electric field of each of the elements using the REV method so as to align the amplitude characteristics and phase characteristics of the radiation electric field of each of the elements; a calibration accuracy evaluation unit that evaluates the calibration accuracy of each element to be lower as the coefficient of determination between a measurement result of the amplitude of a composite radiation electric field of all the elements relative to a rotation phase of the radiation electric field from the phase of the initial radiation electric field of each element and a sine function or cosine function having an arbitrary amplitude and phase is smaller; An array antenna calibration device comprising:

5. A radiation electric field measurement step of measuring the amplitude of a composite radiation electric field of all elements of the array antenna while rotating the phase of the radiation electric field of each element of the array antenna from the phase of the initial radiation electric field using the REV method (element electric field vector rotation method); an amplitude / phase calculation step of calculating the amplitude and phase of the relative radiation electric field of each element based on the amplitude and phase of the initial composite radiation electric field of all the elements using the REV method, based on the amplitude of the composite radiation electric field of all the elements; an amplitude / phase calibration step of calibrating each of the elements using the REV method based on the amplitude and phase of the relative radiation electric field of each of the elements so as to align the amplitude characteristics and phase characteristics of the radiation electric field of each of the elements; a calibration accuracy evaluation step in which the greater the difference between the sum vector across all elements regarding the relative radiation electric field vector of each element, which is composed of the amplitude and phase of the relative radiation electric field of each element, and the initial composite radiation electric field vector of all elements, which is composed of the amplitude and phase of the initial composite radiation electric field of all elements, the lower the calibration accuracy across all elements is evaluated; An array antenna calibration program that causes a computer to execute the above in sequence.

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