JP2005045668A - Method for measuring electrical characteristic of array antenna - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To easily measure a structure parameter of an array antenna system including impedance between individual antenna elements. <P>SOLUTION: In an electronic controlled wave director array antenna system, a first control voltage set is set in each variable reactance element, current on each element including a driven element and each parasitic element is measured, and input impedance of the array antenna system is measured. A second control voltage set is set in each variable reactance element, current on each element is measured, and input impedance of the array antenna system is measured. The structure parameter of an array antenna including impedance between the respective elements are calculated by using a relation among current on each element, input impedance of the array antenna system, the input impedance of the driven element itself, coupling impedance between the driven element and respective parasitic elements, and input impedance of each parasitic element itself mounted with the reactance element on the basis of the measured current and input impedance. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a method for measuring the electrical characteristics of an array antenna that can calculate the electrical characteristics of an array antenna composed of a plurality of antenna elements and having variable directivity characteristics, and more particularly to an electronically controlled waveguide array antenna device ( The present invention relates to a method for measuring the electrical characteristics of an array antenna that can change the directivity characteristics of an electronically steerable passive array radiator antenna.

  Prior art electronically controlled waveguide array antenna devices have been proposed in, for example, Patent Document 1 and Non-Patent Documents 1 to 4. The array antenna device is connected to an excitation element to which a radio signal is fed, at least one non-excitation element that is provided at a predetermined interval from the excitation element and to which no radio signal is fed, and the non-excitation element. The array antenna including the variable reactance element is provided, and the directivity characteristic of the array antenna can be changed by changing the reactance value of the variable reactance element. In this electronically controlled waveguide array antenna device, an inexpensive variable-capacitance diode can be used as a variable reactance element, and since it can be configured with a single feeding system, a compact, lightweight, and low-cost adaptive antenna can be realized. . In addition, since a variable capacitance diode is used with a reverse bias voltage, the power consumption is low, and since a spatial beam is formed, a high dynamic range can be obtained without circuit loss.

  Non-Patent Document 4 discloses a small anechoic chamber (or an anechoic box) for measuring an antenna, and Non-Patent Document 5 discloses a low disturbance for probing the near-field electromagnetic field on the antenna to be measured. The probe is disclosed. Further, Non-Patent Document 6 shows that the near-field measurement of the antenna using the small anechoic chamber in Non-Patent Document 4 and the probe in Non-Patent Document 5 is in good agreement with the result measured in the large anechoic chamber. Is shown.

JP 2001-24431A. Junichi Iigusa et al., “Equivalent Steering Vector and Equivalent Weight Vector Considering ESPAR Antenna's Finite Ground Plane”, IEICE Technical Report, IEICE, AP2003-13, pp. 73-80, April 2003. T. Ohira et al., "Hand-held microwave direction-of-arrival finder based on varactor-tuned analog aerial beamforming", Proceedings of APMC2001, Vol. 2 of 3, pp. 585-588, December 2001. Yuichiro Ohno et al., “Proposal of Routing Method Based on Antenna Scanning Angle vs. SINR Information”, Proceedings of Society Conference of IEICE, IEICE, B-5-109, March 2000. Q. Han et al., “Reactive field anechoic box for ESPAR antenna measurement”, IEICE Transactions on Electronics, E85-C, 7, pp.1451-1459, July 2002. N. Masuda et al., “A miniature high-performance magnetic-field probe for measuring high-frequency currents”, NEC Research & Development, Vol. 42, No. 2, pp. 246-250, April 2001. Q. Han et al., "Array antenna characterization technique based on evanescent reactive-near-field probing in an ultra-small anechoic box", IEEE MTT-S International Microwave Symposium IMS2003, Vol. 3/3, TH4C-3, pp 1841-1844, June 2003.

  The electronically controlled waveguide array antenna apparatus is a variable beam antenna in which variable reactance elements of a semiconductor device are integrated (or integrated). In the post-production inspection, the control voltage calibration for the variable reactance elements is included. Confirmation of the beam forming function is essential. However, since the antenna element and the variable reactance element are integrated, they cannot be measured separately. Since the semiconductor element is directly integrated with the antenna, there is a problem that manufacturing variation of the semiconductor element and its mounting error affect the control characteristics of the antenna. When an electronically controlled waveguide array antenna device is used as an adaptive antenna, some errors can be corrected by a control algorithm (see Non-Patent Document 3), but it is close to a direction detector or a wireless ad hoc network. When routing is performed based on the angle information of the terminal, calibration after manufacture is necessary. Also, if the variable reactance value (or variable capacitance) of the variable reactance element does not cover the required range, the desired operation cannot be expected. It is therefore desirable to provide a method for measuring and calculating the structural parameters of an array antenna device.

  The object of the present invention is to solve the above-mentioned problems, for example, in an array antenna apparatus including a coupling impedance between antenna elements of an array antenna control apparatus such as an electronically controlled waveguide array antenna apparatus and its own input impedance. It is an object of the present invention to provide a method for measuring the electrical characteristics of an array antenna, in which structural parameters can be measured and calculated very easily.

The method for measuring the electrical characteristics of an array antenna according to the present invention includes an excitation element for transmitting and receiving a radio signal, spaced apart from each other by an equal angle around the excitation element, and separated from the excitation element by a predetermined distance. At least one non-excitation element provided, and at least one variable reactance element connected to the non-excitation element, respectively, and a control voltage is set in each of the at least one variable reactance element to A method for measuring the electrical characteristics of an array antenna in which the directivity is changed by operating the at least one non-excited element as a director or a reflector by changing a reactance value,
A first control voltage set is set for the at least one variable reactance element, a current on each antenna element including the excitation element and the at least one non-excitation element is measured, and an input impedance of the array antenna apparatus is determined. Measuring step;
A second control voltage set different from the first control voltage set is set in the at least one variable reactance element, a current on each antenna element is measured, and an input impedance of the array antenna apparatus is measured. Steps,
Based on the measured current and input impedance, the current on each antenna element, the input impedance of the array antenna device, the input impedance of the excitation element itself, the excitation element and the non-excitation element Calculating structural parameters of the array antenna including impedances between the antenna elements using a relational expression between a coupling impedance between the antenna elements and an input impedance of each non-excited element loaded with the variable reactance element. It is characterized by including.

  Further, in the method for measuring the electrical characteristics of the array antenna, the current on each antenna element is measured by using a near-field electromagnetic field measurement method, and the detection unit of at least one magnetic field probe is connected to each antenna element. The magnetic field generated by each antenna element is measured so as to be electromagnetically coupled to the feeding point or the maximum current point, and the current is calculated based on the measured magnetic field.

  Furthermore, in the method for measuring the electrical characteristics of the array antenna, the structural parameters of the array antenna include the coupling impedance between the antenna elements, the input impedance of the excitation element itself, and the variable reactance element loaded therein. Including at least one input impedance of the non-excited element itself.

  Therefore, according to the method for measuring the electrical characteristics of the array antenna according to the present invention, for example, the coupling impedance between the antenna elements of the array antenna control device such as an electronically controlled waveguide array antenna device and the input impedance of itself. The structural parameters of the array antenna device including can be measured and calculated very easily.

  The best mode for carrying out the invention will be described below with reference to the drawings.

  FIG. 1 is a block diagram showing a configuration of an array antenna control apparatus including an array antenna apparatus 100 which is an electronically controlled waveguide array antenna apparatus according to an embodiment of the present invention. As shown in FIG. 1, the array antenna control apparatus of this embodiment includes one excitation element A0 and six non-excitation elements A1 to A6 loaded with variable reactance elements 12-1 to 12-6, respectively. The array antenna apparatus 100 including the ground conductor 11 and the adaptive control controller 20 are configured.

According to the measurement method of the electrical characteristics of the array antenna of the embodiment according to the present invention, as will be described in detail later,
(A) A first control voltage set is set for each of the variable reactance elements 12-1 to 12-6, and each antenna element including the excitation element A0 and each of the non-excitation elements A1 to A6 (hereinafter referred to as the excitation element A0 and each of the non-excitation elements). Measuring the current on the antenna element 100) and measuring the input impedance of the array antenna device 100;
(B) A second control voltage set different from the first control voltage set is set for each of the variable reactance elements 12-1 to 12-6, the currents on the antenna elements A0 to A6 are measured, and the array Measuring the input impedance of the antenna device 100;
(C) Based on the measured current and input impedance, the current on each antenna element A0 to A6, the input impedance of the array antenna device, the input impedance of the excitation element A0 itself, the excitation element A0 and the above Using a relational expression between the coupling impedance between each non-excitation element A1-A6 and the input impedance of each non-excitation element A1 to A6 loaded with each variable reactance element 12-1 to 12-6. And calculating the structural parameters of the array antenna including the impedance between the antenna elements A0 to A6.

  Thus, the coupling impedance between the excitation element A0 and the non-excitation elements A1 to A6, the coupling impedance between the non-excitation elements A1 to A6, the input impedance of the excitation element A0 itself, and the variable reactance elements 12-1 to It is possible to measure and calculate the structural parameters of the array antenna device 100 including the input impedance of each of the non-excited elements A1 to A6 itself loaded with 12-6.

  In the array antenna control apparatus of FIG. 1, the adaptive control type controller 20 is constituted by a digital computer such as a computer, for example. At the time of reception, before starting wireless communication by the demodulator 4, transmission is performed from the other party's transmitter. A learning sequence signal is generated with the same signal pattern as the received signal y (t) when the learning sequence signal included in the radio signal to be received is received by the excitation element A0 of the array antenna apparatus 100. Based on the learning sequence signal r (t) generated by the device 21, for example, adaptive control processing by the steepest gradient method is executed. In this adaptive control processing, bias voltages applied to the variable reactance elements 12-1 to 12-6 for directing the main beam of the array antenna apparatus 100 in the direction of the desired wave and directing null in the direction of the interference wave A value (hereinafter referred to as a control voltage) is searched and set using a control voltage signal. Although the steepest gradient method is used in the above description, the present invention is not limited to this, and other adaptive control methods may be used. An input device 22 such as a keyboard is connected to the adaptive control type controller 20, and before starting wireless communication using the demodulator or the wireless transmitter 7, the user selects an adaptive control method using the input device 22. In doing so, the operation of the adaptive control controller 20 can be controlled.

  In FIG. 1, an array antenna apparatus 100 is composed of seven antenna elements provided on a ground conductor 11, that is, an excitation element A0 and non-excitation elements A1 to A6. The excitation element A0 is on the circumference of a radius r. Are arranged so as to be surrounded by six non-excitation elements A1 to A6. Preferably, the non-excitation elements A1 to A6 are equidistant from each other on the circumference of the radius r (that is, they are equidistant from each other about the excitation element A0 (60 degrees in the example of FIG. 1)). Is provided. Each of the excitation elements A0 and the non-excitation elements A1 to A6 is configured to be a monopole element having a length of about λ / 4 with respect to the wavelength λ of the desired wave, for example, and the radius r is λ / 4. Configured to be. Each antenna element has a diameter of 0.02λ. The feeding point of the excitation element A0 is connected to the low noise amplifier (LNA) 1 via the coaxial cable 5 and the circulator 6, and the non-excitation elements A1 to A6 are connected to the variable reactance elements 12-1 to 12-6, respectively. These variable reactance elements 12-1 to 12-6 change their reactance values in response to a control voltage signal from the adaptive control type controller 20.

  FIG. 2 is a longitudinal sectional view of the array antenna device 100. The excitation element A0 is electrically insulated from the ground conductor 11, and the non-excitation elements A1 to A6 are grounded with respect to the ground conductor 11 via the variable reactance elements 12-1 to 12-6. The operation of the variable reactance elements 12-1 to 12-6 will be described. For example, when the longitudinal lengths of the excitation element A0 and the non-excitation elements A1 to A6 are substantially the same, for example, the variable reactance element 12-1 Is inductive (L property), the variable reactance element 12-1 becomes an extension coil, and the electrical lengths of the non-excitation elements A1 to A6 are longer than that of the excitation element A0, and function as a reflector. On the other hand, for example, when the variable reactance element 12-1 has capacitance (C-type), the variable reactance element 12-1 becomes a shortening capacitor, and the electrical length of the non-excitation element A1 becomes shorter than that of the excitation element A0. Acts as a director. The non-excitation elements A2 to A6 connected to the other variable reactance elements 12-2 to 12-6 operate in the same manner.

  Therefore, in the array antenna apparatus 100 of FIG. 1, the control voltage value applied to the variable reactance elements 12-1 to 12-6 connected to the non-excitation elements A1 to A6 is changed, and the reactance as the junction capacitance value is changed. By changing the value, the plane directivity of the array antenna apparatus 100 can be changed.

  In the array antenna control apparatus of FIG. 1, a transmitting station that transmits a radio signal received by the array antenna 100 has a learning sequence having the same signal pattern as a predetermined learning sequence signal generated by the learning sequence signal generator 21. The radio frequency carrier signal is modulated using a digital modulation method such as BPSK or QPSK in accordance with a digital data signal having a predetermined symbol rate including the signal, and the modulated signal is power-amplified to be array antenna apparatus 100 of the receiving station. Send to. In this embodiment, before performing data communication, a radio signal including a learning sequence signal is transmitted from the transmitting station to the receiving station, and adaptive control processing by the adaptive control type controller 20 is executed at the receiving station.

  The array antenna apparatus 100 receives a radio signal from a transmitting station, and the received signal is input to a low noise amplifier (LNA) 1 through a feeding coaxial cable 5 and a circulator 6 and amplified, and then downed. The converter (D / C) 2 performs low-frequency conversion of the amplified signal into a signal having a predetermined intermediate frequency (IF signal). Further, the A / D converter 3 A / D converts the low-frequency converted analog signal into a digital signal, and outputs the digital signal to the adaptive control controller 20 and the demodulator 4. Next, the adaptive control type controller 20 sequentially perturbs the reactance value of each variable reactance element by a predetermined difference width based on the input received signal y (t) and the learning sequence signal r (t). A predetermined evaluation function value (for example, received signal power) is calculated with respect to the reactance value, and the evaluation function value is maximized using the steepest gradient method based on the calculated evaluation function value. In addition, by repeatedly calculating each reactance value, the reactance value of each variable reactance element for directing the main beam of the array antenna apparatus 100 toward the desired wave and the null toward the interference wave is calculated. Control to set. Thus, the bias voltage value of each variable reactance element for directing the main beam of the array antenna apparatus 100 in the direction of the desired wave and the null in the direction of the interference wave is searched so that the evaluation function value becomes maximum. Then, a control voltage signal having each searched bias voltage value is output to each variable reactance element and set.

  The radio transmitter 7 modulates a radio carrier wave by a predetermined modulation method based on the input transmission baseband signal, and the radio signal that is the modulated radio carrier wave is arrayed via the circulator 6 and the feeding coaxial cable 5. The signal is output to the excitation element A0 of the antenna device 100, whereby a radio signal is radiated from the array antenna device 100.

  FIG. 3 is a perspective view showing a configuration of an array antenna apparatus 110 of a seven-element half-wave dipole antenna that replaces the array antenna apparatus 100 of a quarter-wave monopole antenna of FIG. In the array antenna device 110 of FIG. 3, each of the antenna elements A0 to A6 is extended in the longitudinal direction instead of the ground conductor 11 in the array antenna device 100 of FIG. 1, and is configured as a half-wave monopole antenna element. It is characterized by that.

  Excitation element A10 is a half-wave dipole antenna element composed of upper element A10a and lower element A10b, and each of upper element A10a and lower element A10b has a length in the longitudinal direction of a quarter wavelength. And extending in a straight line. The excitation element A10 includes a feeding point F1 at an end portion on the side where the upper element A10a and the lower element A10b face each other (that is, a central portion in the longitudinal direction of the excitation element A10). The feeding coaxial cable 5 of FIG. 1 is connected to the feeding point F1. The non-excitation element A11 is also a half-wave dipole antenna element composed of an upper element A11a and a lower element A11b. The upper element A11a and the lower element A11b each have a length in the longitudinal direction of a quarter wavelength. And extending in a straight line. End portions of the upper element A11a and the lower element A11b facing each other (that is, a central portion in the longitudinal direction of the non-excitation element A11) are connected to each other via the variable reactance element 12-1. A control voltage signal is applied to the variable reactance element 12-1 as in FIG. The non-exciting elements A12 to A16 are also configured in the same manner as the non-exciting element A11. It is provided in parallel with A10. According to this array antenna apparatus 110, similarly to the array antenna apparatus 100 of FIG. 1, the control voltage values applied to the variable reactance elements 12-1 to 12-6 connected to the non-excitation elements A11 to A16 are changed. Thus, by changing the reactance value that is the junction capacitance value, the plane directivity characteristic of the array antenna device 110 can be changed.

  FIG. 4 is a perspective view showing a configuration of an array antenna apparatus 120 of a two-element half-wavelength dipole antenna that replaces the array antenna apparatus 100 of a quarter-wave monopole antenna of FIG. In the array antenna control device 120 of FIG. 4, the excitation element A20 is configured similarly to the excitation element A10 of FIG. 3, and the non-excitation element A21 is configured similarly to the non-excitation element A11 of FIG. Exciting element A20 and non-exciting element A21 are separated from each other by a predetermined distance (for example, ¼ wavelength) and are provided in parallel to each other. Also in the array antenna device 120, by changing the control voltage value applied to the variable reactance element 12-1 connected to the non-excitation element A21 and changing the reactance value that is the junction capacitance value, the array antenna device 120 is also provided. It is possible to change the plane directivity characteristic.

  FIG. 5 is a perspective view showing a configuration of an array antenna apparatus 130 of a three-element half-wave dipole antenna that replaces the array antenna apparatus 100 of a quarter-wave monopole antenna of FIG. In array antenna apparatus 130, excitation element A30 is configured in the same manner as excitation element A10 in FIG. 3, and non-excitation elements A31 and A32 are configured in the same manner as non-excitation elements A11 and A14 in FIG. The excitation element A30 and the non-excitation element A31, and the excitation element A30 and the non-excitation element A32 are separated from each other by a predetermined interval (for example, ¼ wavelength), and are provided in parallel to each other. Also in the array antenna apparatus 130, the control voltage value applied to the variable reactance elements 12-1 and 12-2 connected to the non-excitation elements A31 and A31 is changed, and the reactance value that is the junction capacitance value is changed. As a result, the plane directivity of the array antenna apparatus 130 can be changed.

  A method for measuring and calculating the structural parameters of the array antenna apparatus 100 used in the array antenna control apparatus described above with reference to FIG. 1 will be described.

  FIG. 6 is a block diagram showing a configuration of a structure parameter measurement calculation system for an array antenna apparatus according to an embodiment of the present invention. The measurement calculation system includes a small anechoic box 40 that houses the array antenna device 100 to be measured and the probes 32-0 to 32-6 provided close to the antenna elements A0 to A6 of the array antenna device 100. The measurement calculation system further includes a network analyzer 31 connected to the array antenna apparatus 100 and the probes 32-0 to 32-6, and an antenna measurement controller 30 that executes measurement calculation processing of the structure parameters of the array antenna. ing. The antenna measurement controller 30 uses the D / A converter 34 to output a control voltage signal including a control voltage set for generating a predetermined reactance value set to the variable reactance elements 12-1 to 12-6 of the array antenna apparatus 100. The high-frequency magnetic field in the near-field on each antenna element A0 to A6 of the array antenna apparatus 100 at this time is measured using the probes 32-0 to 32-6 and the network analyzer 31, and the array antenna apparatus 100 input impedances are measured using the network analyzer 31. Here, the tip detectors of the probes 32-0 to 32-6 are close to each other to be electromagnetically coupled to the feeding points or the current maximum points of the antenna elements A0 to A6, and detect the magnetic field at that point. Based on this, the current can be calculated.

  In the present embodiment, in order to shorten the measurement time and to eliminate the need for troublesome probe positioning for each antenna element during measurement, it is possible to simultaneously measure the pole near field of all the antenna elements A0 to A6. A measurement calculation system with a plurality of probes was constructed.

  The small anechoic box 40 shown in the longitudinal sectional view of FIG. 6 has, for example, a cubic outer shape with dimensions of 630 mm × 630 mm × 630 mm, and a radio wave absorber 41 is mounted on its six inner surfaces. No. 41 has a shape formed by repeating a pyramid shape having a sharp tip, and the material is a polyurethane foam impregnated with carbon. The array antenna device 100 is rotatably supported by the rotation shaft 42 so that the array antenna device 100 is positioned at the center of the small anechoic box 40.

  In the present embodiment, each of the probes 32-0 to 32-6 is, for example, a CP-2S type low disturbance multilayer substrate type magnetic field probe manufactured by NEC Vacuum Glass Corporation, and each of the probes 32-0 to 32-6. The detection tip of each of the antenna elements A0 to A6 is not in contact with the antenna elements A0 to A6, so that they are electromagnetically coupled to each other at a feeding point or a current maximum point close to the ground conductor 11 of each antenna element A0 to A6. For example, 0.05 mm) is arranged close to each other, and the magnetic field near the antenna is measured. Therefore, the magnetic field in the vicinity of the antenna shows a value substantially proportional to the high-frequency current flowing in the vicinity of the variable reactance elements 12-1 to 12-6, and the high-frequency current is obtained by observing the frequency spectrum of the measurement output signal of the magnetic field. The corresponding power level can be measured. In this embodiment, the experimental cost is greatly reduced by using the very near field measurement method using the low disturbance probe magnetic field probes 32-0 to 32-6 and the small anechoic box 40.

  The probe 32-0 has a probe moving mechanism 36, a probe moving mechanism 36, and a probe moving mechanism 36 in order to remove the influence on the other probes 32-1 to 32-6 when measuring the currents on the non-excited elements A1 to A6. The probe antenna can be separated from the array antenna apparatus 100 by using a probe support member 36a that mechanically connects the probe 32-0. The probe 32-0 is connected to the contact c2 of the switch S1 via the cable 33-0, and each probe 32-1 to 32-6 is connected to the contact c3 of the switch S2 via the cables 33-1 to 33-6, respectively. To c8. The switch S2 connects any one of the contacts c3 to c8 to the contact c1 of the switch S1, and the switch S1 is a measurement output signal representing the currents on the antenna elements A0 to A6 measured by the probes 32-0 to 32-6. Is input to the network analyzer 31.

  The antenna measurement controller 30 of the measurement calculation system includes a network analyzer 31, a position controller 35, a switch via an IEEE-488 / GP-IB bus 38 to achieve fully automated amplitude and phase measurements. Each of S1 and S2 is connected to the processing memory 39 via a predetermined interface. The D / A converter 34 converts the bias voltage output as a digital value from the antenna measurement controller 30 into an analog control voltage signal, and outputs the control voltage signal to each of the variable reactance elements 12-1 to 12-6 for setting. To do. The network analyzer 31 stores the measured high frequency current and input impedance in the processing memory 39 via the bus 38. The antenna measurement controller 30 stores the calculated structural parameters of the array antenna device 100 in the processing memory 39 via the bus 38.

  The position controller 35 rotates the array antenna apparatus 100 by rotating the probe moving mechanism 36 that moves the probe 32-0 close to or away from the excitation element A0 and the rotating shaft 42 of the array antenna apparatus 100. The rotation mechanism 37 that holds the position at a predetermined angle is controlled.

  In the measurement calculation system according to the present embodiment, only the array antenna device 100 to be measured and the probes 32-0 to 32-6 are provided in the anechoic box 40, and other components are arranged outside the anechoic box 40. Is done. Thereby, reflection of unnecessary radio waves in the anechoic box 40 can be prevented.

  Since the small anechoic box 40 of FIG. 6 is shown to obtain accurate measurement values similar to those obtained in a large anechoic chamber (see Non-Patent Document 6), in this embodiment, a conventional large anechoic box 40 is used. The high-frequency magnetic field in the very near field of the array antenna apparatus 100 is measured using the low-interference probes 32-0 to 32-6 in the small anechoic box 40 instead of the anechoic chamber. One of the advantages of the near-field measurement system is that there is almost no reflection from a measuring instrument such as a positioner that is usually installed inside an anechoic chamber. Furthermore, instead of using a measurement antenna different from the array antenna apparatus 100, probes 32-0 to 32-6 for detecting the current in the near field of the element are used. Therefore, the distance between the probes 32-0 to 32-6 and the antenna to be measured is extremely short. Actually, in the measurement performed for the present embodiment, the probes 32-0 to 32-6 have a distance from the tip of the probes 32-0 to 32-6 to the variable reactance element of 0. It is arranged at a place of 05 mm. In addition to the advantages described above, the small anechoic box 40 can be used effectively in the same way as a conventional measuring instrument. That is, it is easy to move and convenient for use on a desk. This near-field measurement technique significantly reduces the time and cost of the experiment.

  In the following, a description will be given of a pole vicinity measurement method used in the method for measuring the structural parameters of the array antenna apparatus according to the present embodiment.

  As shown in FIG. 6, the near-field measurement method includes a small anechoic box 40 (see Non-Patent Document 4) and low-disturbance probes 32-0 to 32-6 (see Non-Patent Document 5). This is a method for detecting a near-field electromagnetic field on an antenna to be measured. The present inventors have so far picked up the evanescent magnetic fields of the excitation element and each non-excitation element of the electronically controlled waveguide array antenna apparatus by the near-field measurement method with a low disturbance magnetic field probe, and based on the measured magnetic field. The current was calculated and the directivity pattern of the antenna was estimated. It was shown that the result was in good agreement with the pattern measured in a large anechoic chamber (see Non-Patent Document 6).

  When the control voltage of the variable reactance element 12-m (m = 1, 2,..., 6) loaded on a certain non-excitation element Am (m = 1, 2,..., 6) changes, The current also changes. In addition, the RF current on each non-excited element Am not only depends on the reactance value of the variable reactance element 12-m loaded on the non-excited element Am itself, but also includes other non-excited elements An ( n ≠ m; n = 1, 2,..., 6) also depends on the reactance value of the variable reactance element 12-n loaded. To know the current over the entire range of the control voltage of the variable reactance element 12-m, the number of measurements is enormous. Here, the electromagnetic coupling part between the elements is regarded as a circuit network having a high-frequency port, and the port voltage and the current are related by an impedance matrix having the impedance between the antenna elements as a component. The radiation resistance of each antenna element and the electromagnetic coupling between the antenna elements are completely included in the impedance matrix. An approach is proposed in which the structural parameters are calculated with a small number of measurements using the fact that the impedance matrix does not depend on the capacitance of the variable reactance element 12-m or the external signal source. If the reactance values of the impedance matrix and the variable reactance element 12-m can be calculated, the equivalent weight vector model is completely determined.

First, the array antenna apparatus 110 of FIG. 3 is modeled, and a method for calculating the structural parameters from the array antenna apparatus 110 is formulated. In the following description, the number of non-exciting elements is generalized to M, and is expressed as non-exciting elements Am (m = 1, 2,..., M) for simplification. In FIG. 3, a reactance vector including the reactance values x ₁ ,..., X _M of the variable reactance element 12-m (m = 1, 2,..., M) as components is defined as follows.

Here, the superscript T represents transposition. Further, during the calculation process, the reactance values x ₁ ,..., X _M are each multiplied by an imaginary unit j. Hereinafter, although the transmission operation of the array antenna apparatus 110 will be described, generality is not lost by the reciprocity theorem. Assume that the output impedance of the wireless transmitter 7 when the array antenna device 110 is operated for transmission is z _s . Further, the RF current on the excitation element A0 and _{i 0,} parasitic elements Am (m = 1,2, ..., M) i 1 the RF current _on, i 2, ..., a _{i M.} The direction of each current is a direction in which the current flows from the variable reactance element 12-m (m = 1, 2,..., M) toward the upper element Ama of the non-excitation element Am connected to the variable reactance element 12-m. The positive direction. A current vector i including the above currents i ₀ ,..., I _M as components is defined as follows.

  Each component of the current vector i acts as a weight (weighting coefficient) for each antenna element Am (m = 0, 1,..., M) in the array antenna apparatus 110.

  A closed circuit equation based on Kirchhoff's law for a circuit including each antenna element Am (m = 0, 1,..., M), a wireless transmitter 7, and a variable reactance element 12-m (m = 1, 2,..., M). From the above, the following equation is derived (see Non-Patent Document 1).

Here, u ₀ is the M + 1-dimensional unit vectors in the following equation.

Further, v _s is an open circuit voltage of the wireless transmitter 7, and X is a diagonal of the output impedance of the wireless transmitter 7 and the reactance value x _m of the variable reactance element 12-m (m = 1, 2,..., M). This is the matrix of the following equation for the component.

  Z is an M + 1 order impedance matrix having an impedance between each antenna element Am (m = 0, 1,..., M) in the array antenna apparatus 110 as a component expressed by the following equation.

When the arrangement of the non-excitation elements Am (m = 1, 2,..., M) has a cyclic symmetry with respect to the excitation element A0, (M + 1) ^{2 of the} impedance matrix Z Among the elements, the independent elements are 3+ (M−1) / 2 when the number M of non-excited elements is odd, and 3 + M / 2 when the number M of non-excited elements is even.

Also,
(A) z ₀₀ represents the input impedance of the excitation element A 0 itself,
(B) z ₀₁ represents a coupling impedance between the excitation element A0 and the non-excitation element Am (m = 1, 2,..., M),
(C) z ₁₁ represents the input impedance of the non-excited element Am itself,
(D) z _Mn represents a coupling impedance between the non-excited element AM and the non-excited element An.

Here, when n = M / 2 (when M is an even number) or when n = (M−1) / 2 (when M is an odd number), z _1n = z _Mn holds. These independent elements are structural parameters of the array antenna device 110. The radius, length, and / or interval of each antenna element Am (m = 0, 1,..., M), the ground conductor 11 (the array of FIG. It is determined by the size and shape of the antenna device 100).

An inverse matrix operation is included in the relational expression (see Equation 3) between the current vector i and the reactance values x ₁ ,..., X _M. For example, if the value of a certain variable reactance element 12-m (m = 1, 2,..., M) is changed, the current on the non-excitation element Am of that system (that is, the phase of the current and the current) (Amplitude) not only changes, but also means that the current on the antenna elements An (n = 0, 1,..., M; n ≠ m) of other systems also changes. The elements of the impedance matrix Z can be obtained from the structural parameters of the array antenna device 110 by high-frequency electromagnetic field analysis (for example, the moment method). Focusing on the fact that these elements are invariable with respect to the control voltage applied to the variable reactance element 12-m, in the present embodiment, the current measurement is performed twice (the near-field electromagnetic field using Equation 3). We propose a method for obtaining the elements of the impedance matrix Z in measurement). At the same time, the reactance value of the mounted variable reactance element 12-m is obtained. The formulation is shown below.

First, in the first measurement, a control voltage set (v ₁ , v ₂ ,..., V _M ) is applied to each variable reactance element 12-m (m = 1, 2,..., M). The reactance value set (jx ₁ , jx ₂ ,..., Jx _M ) (this is unknown) of the variable reactance element 12-m, and the current (i ₀ , i) on each antenna element Am obtained by the measurement at this time Substituting ₁ ,..., I _M ) into Equation 3 for expansion, the following equation is obtained.

Here, it is assumed that the current i ₀ on the excitation element A ₀ ≠ 0, and the current values on all the non-excitation elements Am (m = 1, 2,..., M) are normalized with the current i ₀ . This means that the calibration of the current measurement system itself is not required by regarding the current on the excitation element A0 as a reference signal in actual measurement. When a reactance set consisting of M reactance values is used, if the number M of non-excited elements is an even number with respect to the simultaneous equations of Equation 6 consisting of M + 1 equations, the unknown number is M + 3 + M / 2. If the number M of the non-excitation elements is an odd number, the unknown number is M + 3 + (M−1) / 2. However, in the array antenna apparatus 110, the non-excitation element Am and the variable reactance element 12-m are integrated. so regarded za _k represented by the following formula and one unknown independent variables.

In the present embodiment, the za _k is referred to as "the input impedance of the parasitic elements themselves variable reactance element is loaded." Accordingly, as apparent from the equation 8, the value of the input impedance za _k itself includes both an input impedance _{z 11} of the parasitic elements Am itself, and a reactance value jx _m of the variable reactance element 12-m.

Next, in the second measurement, the same measurement is performed by changing the control voltage set applied to each variable reactance element 12-m (m = 1, 2,..., M). M + 1 equations are obtained from the measurement. Since 2 (M + 1) equations can be obtained from 2 (M + 1) equations by combining the two measurements, the control voltage (reactance value (new unknown) of the variable reactance element 12-m that can be changed by the second measurement is obtained. )) Is 2 (M + 1)-(M + 3 + M / 2-1) = M / 2 if the number M of non-excited elements is an even number, and 2 (if the number M of non-excited elements is an odd number) M + 1) − (M + 3 + (M−1) / 2-1) = (M + 1) / 2. In the second measurement, in the M variable reactance elements 12-m, when the number M of non-excited elements is an even number, only K = M / 2 control voltages or the number M of non-excited elements Is an odd number, only K = (M + 1) / 2 control voltages are changed from the values in the first measurement. In the description of the present embodiment, as an example, only K control voltages v ₁ ,..., V _K are changed, but other control voltage sets (for example, v ₂ ,..., V _{K + 1} ) may be used. At this time, only K of the elements of the reactance set (jx ′ ₁ , jx ′ ₂ ,..., Jx ′ _K , jx _{K + 1} ,..., Jx _M ) change, but all elements of the current vector i change. When the current value at this time is expressed as (i ₀ ′, i ₁ ′,..., I _M ′), the following equation is obtained from the equation based on Kirchhoff's law of Equation 3, as in Equation 7.

Furthermore, the term v _s / i ₀ −z _{s on} the right side of the first equation of Equation 7 and the term v _s / i ₀ ′ −z _{s on} the right side of the first equation of Equation 9 are respectively input to the antenna. Impedances z _in and z _in ′, and the following equation holds.

These input impedances z _in and z _in ′ are measured by the network analyzer 31 (use of one port) in the state where the control voltage is applied to each variable reactance element 12-m in the measurement calculation system of FIG. .

The first equations in the simultaneous equations of Equations 7 and 9 are respectively the coupling impedance of the excitation element A0 and the non-excitation element Am (m = 1, 2,..., M), the input impedance of the excitation element A0 itself, the antenna Only the input impedance of the non-excited element Am. That is, the impedances z ₀₀ and z ₀₁ can be calculated from the following simultaneous equations for the two unknowns of the impedances z ₀₀ and z ₀₁ .

  By rearranging the second and subsequent equations of Equation 7 and Equation 9, the following Equations 14 and 15 are obtained, respectively.

The right side of these equations means an induced voltage generated by coupling from the excitation element A0 to the non-excitation element Am (m = 1, 2,..., M). From these simultaneous equations, all 2 (M + 1) −2 unknowns excluding impedances z ₀₀ and z ₀₁ can be calculated.

  For example, in the case of the 7-element (M = 6) array antenna apparatus 110 shown in FIG. 3, the number of unknowns in two measurements is 14. An equation in matrix form for obtaining these (an equation that summarizes simultaneous equations used in two measurements) is shown in Equation 1 of FIG. The antenna measurement controller 30 in FIG. 6 executes the measurement calculation process for the structural parameters of the array antenna apparatus in FIG. 8 using Equation 1 in FIG.

  FIG. 8 is a flowchart showing the measurement calculation processing of the structural parameters of the array antenna apparatus, which is executed by the antenna measurement controller 30 of FIG. 6 in accordance with the principle described above.

In step S1 of FIG. 8, first, using the D / A converter 34, a control voltage signal for generating a first reactance value set is output and set to the variable reactance elements 12-1 to 12-6. Next, in steps S2 to S7, the current i ₀ ,... On each antenna element when the first reactance value set is set to each variable reactance element 12-1 to 12-6 by the pole near-field measurement method. the i ₆ is measured. In step S2, using the position controller 35, the probe moving mechanism 36, and the probe support member 36a, the probe 32-0 is disposed in the vicinity of the feeding point of the excitation element A0, the switch S1 is connected to the contact c2, and the probe 32 is connected. The current i ₀ on the excitation element A ₀ is measured using −0 and the network analyzer 31 and stored in the processing memory 39. In step S3, the probe 32-0 is separated from the array antenna apparatus 100 using the position controller 35, the probe moving mechanism 36, and the probe support member 36a, and the switch S1 is connected to the contact c1. In steps S4 to S7, the current i ₁ on each non-excited element A1 to A6 when the first reactance value set is set to each variable reactance element 12-1 to 12-6 by the near-field measurement method. ..., to measure the _{i 6.} Set the parameter m to 1 at step S4, then in step S5, to connect the switch S2 to the contact m + 2, and measuring the current _{i m} of the parasitic elements Am using a probe 32-m and a network analyzer 31, Store in the processing memory 39. If the parameter m is not 6 or more in step S6, the parameter m is incremented by 1 in step S7, and the process returns to step S5. When the parameter m is 6 or more in step S6, the process proceeds to step S8. In step S <b> 8, the input impedance z _in of the array antenna apparatus 100 is measured using the network analyzer 31 and stored in the processing memory 39.

Next, in step S9 in FIG. 9, the D / A converter 34 is used to output and set a control voltage signal for generating the second reactance value set to the variable reactance elements 12-1 to 12-6. The second reactance value set differs from the first reactance value set only in three elements corresponding to the variable reactance elements 12-1 to 12-3. Next, in steps S10 to S15, the current i ₀ ′ on each antenna element when the second reactance value set is set to each variable reactance element 12-1 to 12-6 by the pole near-field measurement method. , I ₆ '. In step S10, using the position controller 35, the probe moving mechanism 36, and the probe support member 36a, the probe 32-0 is disposed in the vicinity of the excitation element A0, the switch S1 is connected to the contact c2, and the probe 32-0 and The network analyzer 31 is used to measure the current i ₀ ′ on the excitation element A 0 and store it in the processing memory 39. In step S11, the probe 32-0 is separated from the array antenna apparatus 100 using the position controller 35, the probe moving mechanism 36, and the probe support member 36a, and the switch S1 is connected to the contact c1. In steps S12 to S15, the current i ₁ ′ on the non-excited elements A1 to A6 when the second reactance value set is set to each of the variable reactance elements 12-1 to 12-6 by the near-field measurement method. , ..., i ₆ 'is measured. In step S12, the parameter m is set to 1, and then in step S13, the switch S2 is connected to the contact m + 2, and the current im _m 'on the non-excited element Am is measured using the probe 32-m and the network analyzer 31. And stored in the processing memory 39. If the parameter m is not 6 or more in step S14, the parameter m is incremented by 1 in step S15, and the process returns to step S13. When the parameter m is 6 or more in step S14, the process proceeds to step S16. In step S <b> 16, the input impedance z _in ′ of the array antenna apparatus 100 is measured using the network analyzer 31 and stored in the processing memory 39.

Finally, in step S17, based on the measured and stored currents i ₁ ,..., I ₆ , i ₁ ′,..., I ₆ ′ and the input impedances z _in and z _in ′, Equation 1 in FIG. The structure parameter of the array antenna apparatus 100 is calculated using the calculation. Specifically, the structural parameters calculated here are:
(A) the input impedance z ₀₀ of the excitation element A10 itself;
(B) coupling impedance z ₀₁ between the excitation element A10 and the non-excitation element A11;
(C) a coupling impedance z ₁₂ between adjacent non-excited elements;
A coupling impedance z ₁₃ between the parasitic element adjacent in between the (d) 1 single parasitic element,
(E) a coupling impedance _{z 14} between parasitic elements facing each other across the excitation element A10,
(F) the input impedances za ₁ ,..., Za _{6 of} the non-excitation element itself loaded with the variable reactance element, each including a value in the first reactance value set in each of the non-excitation elements A11 to A16;
(G) The input impedances za ₁ ′, za ₂ ′, za ₃ ′ of the non-excitation element itself loaded with the variable reactance element, including the values in the second reactance value set in the non-excitation elements A11 to A13, respectively. including.

The measurement computer 30 in FIG. 6 further calibrates the control voltage versus reactance value characteristics of the variable reactance elements 12-1 to 12-6 of the array antenna based on the structure parameters of the array antenna apparatus 100 measured as described above. can do. The antenna measurement controller 30 repeats the measurement calculation process of FIGS. 8 and 9 using the control voltage signal including various control voltage sets, and sets the control voltage set respectively set in step S1 of each iteration, Based on the calculated input impedances za ₁ ,..., Za _{6 of} the non-excited elements loaded with the variable reactance elements, the control voltage versus reactance value characteristics of the variable reactance elements 12-1 to 12-6 are calculated. Ask. The antenna measurement controller 30 can calibrate the control voltage versus reactance value characteristic based on the obtained control voltage versus reactance value characteristic of each of the variable reactance elements 12-1 to 12-6. Accordingly, the variable reactance values of the variable reactance elements 12-1 to 12-6 of the array antenna apparatus 100 can cover a range necessary for the array antenna apparatus 100 to perform a desired operation. As described above, since the calibration of the array antenna apparatus 100 can be easily executed, when the array antenna apparatus 100 is used as a direction detector or when routing is performed based on angle information of a nearby terminal in a wireless ad hoc network, The manufacturing process can be made simple and inexpensive.

  As described above, according to the method for measuring the electrical characteristics of the array antenna device according to the embodiment of the present invention, the high-frequency magnetic field in the vicinity of each antenna element A0 to A6 is measured, and the current is calculated based on this measurement. Thus, the parameters of the equivalent weight vector model (structure parameters and variable reactance element control characteristics) can be calculated. By paying attention to the fact that the impedance matrix of the array antenna apparatus 100 does not depend on the capacitance of the variable reactance elements 12-1 to 12-6 or the external signal source, the necessary number of measurements can be minimized. As a result, it was shown that the structural parameters can be calculated by magnetic field measurement when two different control voltage sets are set independently of the number of antenna elements. Furthermore, the control voltage versus reactance value characteristic of the variable reactance elements 12-1 to 12-6 can be calibrated by this method. Therefore, according to the measurement method of the electrical characteristics of the array antenna apparatus of the present embodiment, the cost of measurement evaluation of the array antenna apparatus 100 can be greatly reduced.

  Hereinafter, a simulation in which the structural parameters of the array antenna devices 120 and 130 of FIGS. 4 and 5 are calculated using the method for measuring the electrical characteristics of the array antenna device according to the embodiment of the present invention will be described.

  In order to execute the structural parameter measurement calculation processing of the array antenna apparatus of FIGS. 8 and 9, it is necessary to actually measure the current on each antenna element and the input impedance of the feed port. However, for the sake of simplicity, the measurement calculation processing of the present embodiment is verified using the result data of the electromagnetic field simulation. Specifically, current and input impedance are calculated in advance using a commercially available moment method simulator package, and parameter calculation is performed based on this.

First, a simulation is performed to calculate the structural parameters of the array antenna device 120, which is the two-element electronically controlled waveguide array antenna device shown in FIG. When the current versus reactance of the excitation element A0 and the non-excitation element A1 of the array antenna apparatus 120 is calculated by the moment method, it is as shown in FIG. Here, the voltage v _s = 1V at the feeding point F2 and the impedance z _s = 50 W were set.

  Using these current values shown in FIG. 10, the structural parameters and reactance values of the array antenna apparatus 120 are calculated by solving the following four-way simultaneous equations.

Here, the input impedance z _in = v _s / i ₀ and z _in ′ = v _s / i ₀ ′, and the voltage v _s also use values of the calculation result of the moment method. In the simulation, since the reactance value jx ₁ is known, the impedance z ₁₁ can be calculated from the input impedance za ₁ = z ₁₁ + jx _{1 of} the non-excitation element itself loaded with the variable reactance element. The result of the calculated structural parameter is shown in FIG. A comparison between impedances z ₁₁ and z ₀₀ is shown in FIG. Each parameter in FIG. 12 is a theoretical value by the moment method.
(A) z ₀₀ = 70.844-j5.0369,
(B) z ₀₁ = 38.3617-j29.8264, and (c) z ₁₁ = 70.844-j5.0369
Compared with, the real part matches with accuracy within ± 0.17Ω and the imaginary part with accuracy within ± j0.28Ω.

  Next, a similar simulation is performed with three elements. In this simulation, the array antenna apparatus 130 which is the three-element electronically controlled waveguide array antenna apparatus shown in FIG. 5 was used. In this case, in two measurements, three structural parameters and three input impedances of the non-excited element loaded with the variable reactance elements are calculated from the following six-dimensional simultaneous equations.

FIG. 13 shows the current versus reactance values of the antenna elements A30, A31, and A32 of the three-element array antenna apparatus 130 calculated by the moment method. Here, the voltage v _s = 1 V at the feeding point F3 and the impedance z _s = 50 W were set.

The results of the calculated parameters are shown in FIG. Each parameter in FIG. 14 is a theoretical value by the moment method.
(A) z ₀₀ = 70.3438−j5.089,
(B) z ₀₁ = 38.5236-j29.3194
(C) z ₁₁ = 71.4561-j4.806, and (d) z ₁₂ = −14.3802-j28.8879
Compared with, the real part has an accuracy within ± 0.5Ω and the imaginary part has an accuracy within ± j0.3Ω.

Next, calibration of control characteristics of the variable reactance element 12-m (m = 1, 2,..., M) will be described. Once the structural parameters of the array antenna apparatus are obtained, the control voltage versus reactance value of each variable reactance element 12-m can be easily calibrated. Here, the variable reactance element is loaded on the assumption that the structural parameters (z ₀₀ , z ₀₁ , z ₁₂ , z ₁₃ , z ₁₄ ) of the array antenna apparatus 110 that is a seven-element electronically controlled waveguide array antenna apparatus are known. input impedance of the parasitic element itself is _{za n (n = 1,2, ...} , 6) is calculated. From Equation 14, the following equation holds.

  As can be seen from these equations, the input impedance of the non-excited element itself loaded with the variable reactance element is determined only by the structural parameters of the array antenna 110 and the current on each antenna element.

Here, (M + 1) times of current measurement for the excitation element A0 and each of the M non-excitation elements A1 to AM is defined as one set of current measurement. In the above-described processing, the following procedure is performed.
(S1) A certain control voltage set is given to the M variable reactance elements 12-1 to 12-M, and one set of current measurement and one input impedance measurement are performed.
(S2) Next, by changing only the control voltage of one variable reactance element (for example, the first) of the M variable reactance elements 12-1 to 12-M, Perform one input impedance measurement.
(S3) several 12 to several 13 to calculate the impedance _{z 00} and _{z 01.}
(S4) to the impedance _{z 12} from several 14 to several 15 _{z 1M} and za ₁ to Zam, it calculates the za1 '.
By performing the above procedure,
(I) all the elements other than the impedance z ₁₁ among the (M / 2 + 3) independent elements of the Z matrix;
(Ii) the input impedance of the non-excitation element itself loaded with M variable reactance elements 12-1 to 12-M;
(Iii) Only the variable reactance element whose control voltage is changed can calculate the input impedance of the non-excitation element itself loaded with the variable reactance element with respect to the voltage.

Once the elements of the Z matrix other than the impedance z ₁₁ are obtained in this way, they can be handled as known constants because they do not depend on the capacitance of the variable reactance element or the external signal source. Using this result, calibration data of the input impedance values za _{1 to} za _M of the non-excited elements loaded with the M variable reactance elements 12-1 to 12-M in the mounted state are obtained by the following procedure. Can do.
(S11) A control voltage set is given to the M variable reactance elements 12-1 to 12-M, and one set of current measurements is performed. Here, the input impedance measurement is unnecessary.
(S12) Impedances za _{1 to} za _M are calculated from the following M-ary simultaneous equations.

(S13) The control voltages of all the M variable reactance elements 12-1 to 12-M are changed at the same time, and one set of current measurements is performed.
(S14) Impedances za _{1 to} za _M for the control voltage are calculated in the same manner as in the above processing (S12).
(S15) When the above processes (S13) and (S14) are repeated N times, impedance values for different control voltages at N points can be calculated for each of the impedances za _{1 to} za _M.

When the calibration data of the input impedance values za _{1 to} za _M of the non-excited elements loaded with all the variable reactance elements can be calculated in this way, the impedances za _{1 to} za _M for any control voltage set can be interpolated or fitted to the model. Required by Then, the relative values of the currents i _{1 to} i ₆ (when M = 6) can be calculated from the above equation (24). An example of the current value obtained by this method is shown below.

  Once the relative value of the current is obtained, the normalized radiation pattern can be easily calculated by the equivalent weight vector model.

In the case of (M + 1) elements, the number of measurements of this method is as follows: 2 (M + 1) current measurements and 2 input impedance measurements when the first Z matrix is extracted, and N (M + 1) current measurements when acquiring calibration data ( N is the number of calibration data points). In contrast, in the direct to a method for measuring a current i ₁ to i _6, When the measurement of N times in each dimension in the M-dimensional parameter space, it is necessary to N ^M measurements in total. For example, in the case of 7 elements when M = 6, if the range of 0 to 100Ω is measured in increments of 10Ω, the number of measurements of the current measurement method is N _M = million times, but with this method, (2 + N) (M + 1) + 2 = 86 measurements are sufficient.

  The electronically controlled waveguide array antenna device is a variable directional antenna in which a non-excitation element and a variable reactance element (variable reactance element diode) are integrated, and each characteristic cannot be measured separately. Therefore, in the method for measuring the electrical characteristics of the array antenna device according to the embodiment of the present invention, the high-frequency magnetic field in the vicinity of each antenna element is measured, and the current is calculated based on the measured high-frequency magnetic field. A method to calculate structural parameters and variable reactance element control characteristics was proposed. By paying attention to the fact that the impedance matrix of an array composed of a plurality of antenna elements does not depend on the capacitance of the variable reactance element or the external signal source, the necessary number of measurements can be minimized. As a result, it was shown that the structural parameters can be calculated by the magnetic field measurement when two different control voltage sets are set without depending on the number of antenna elements. Further, the voltage control characteristic of the capacitance of the variable reactance element can be calibrated by this method. Therefore, according to the method for measuring the electrical characteristics of the array antenna apparatus of the present embodiment, the cost of measuring and evaluating the array antenna apparatus can be greatly reduced.

It is a block diagram which shows the structure of the control apparatus of an array antenna provided with the array antenna apparatus 100 of the 7 element 1/4 wavelength monopole antenna which is embodiment which concerns on this invention. It is a longitudinal cross-sectional view which shows the detailed structure of the array antenna apparatus 100 of FIG. FIG. 2 is a perspective view showing a configuration of an array antenna apparatus 110 of a seven-element half-wave dipole antenna that replaces the array antenna apparatus 100 of a quarter-wave monopole antenna of FIG. 1. FIG. 2 is a perspective view showing a configuration of an array antenna apparatus 120 of a two-element half-wavelength dipole antenna that replaces the array antenna apparatus 100 of a quarter-wave monopole antenna of FIG. 1. FIG. 2 is a perspective view showing a configuration of an array antenna device 130 of a three-element half-wave dipole antenna that replaces the array antenna device 100 of a quarter-wave monopole antenna of FIG. 1. It is a block diagram which shows the structure of the measurement calculation system of the structural parameter of an array antenna apparatus which is embodiment which concerns on this invention. It is a figure which shows Formula 1 used in the measurement calculation process of the structural parameter of an array antenna apparatus performed by the antenna measurement controller 30 of FIG. It is a flowchart which shows the 1st part of the measurement calculation process of the structural parameter of an array antenna apparatus performed by the antenna measurement controller 30 of FIG. It is a flowchart which shows the 2nd part of the measurement calculation process of the structural parameter of an array antenna apparatus performed by the antenna measurement controller 30 of FIG. FIG. 5 is a graph showing simulation results of the array antenna device 120 of FIG. 4 and currents on the antenna elements A20 and A21 of the array antenna device 120. FIG. FIG. 5 is a graph showing simulation results of the array antenna apparatus 120 of FIG. 4 and showing calculated structure parameters of the array antenna apparatus 120. FIG. FIG. 6 is a graph showing a simulation result of the array antenna apparatus 120 of FIG. 4 and showing a comparison of impedances z ₁₁ and z ₀₀ in the array antenna apparatus 120. FIG. FIG. 6 is a graph showing simulation results of the array antenna device 130 of FIG. 5 and currents on the antenna elements A30, A31, and A32 of the array antenna device 130. FIG. 6 is a graph showing a simulation result of the array antenna apparatus 130 of FIG. 5 and showing the calculated structural parameters of the array antenna apparatus 130. FIG.

Explanation of symbols

A0, A10, A20, A30 ... excitation elements,
A1 to A6, A11 to A16, A21, A31, A32 ... non-excitation elements,
A10a, A11a to A16a, A20a, A21a, A30a, A31a, A32a ... upper element,
A10b, A11b to A16b, A20b, A21b, A30b, A31b, A32b ... lower element,
F1, F2, F3 ... feeding point,
1 ... Low noise amplifier (LNA),
2 ... Down converter,
3 ... A / D converter,
4 ... demodulator,
5 ... Coaxial cable for feeding,
6 ... circulator,
7 ... Wireless transmitter,
11: Ground conductor,
12-1 to 12-6 ... variable reactance element,
20 ... Adaptive control type controller,
21 ... Learning sequence signal generator,
30 ... Antenna measurement controller,
31 ... Network analyzer,
32-0 to 32-6 ... probes,
33-0 to 33-6 ... cable,
34 ... D / A converter,
35 ... Position controller,
36 ... Probe moving mechanism,
37 ... rotation mechanism,
38 ... Bus,
39: Processing memory,
40 ... Anechoic chamber,
41 ... A radio wave absorber,
S1, S2 ... switch,
100, 110, 120, 130... Array antenna device.

Claims (3)

An excitation element for transmitting and receiving a radio signal; at least one non-excitation element provided at an equal angle with respect to the excitation element as a center and spaced apart from the excitation element by a predetermined distance; and the non-excitation element At least one variable reactance element connected to each other, and by setting a control voltage to each of the at least one variable reactance element and changing a reactance value of the variable reactance element, the at least one non-excited element Is a method for measuring the electrical characteristics of an array antenna whose directivity changes by operating as a director or a reflector, respectively,
A first control voltage set is set for the at least one variable reactance element, a current on each antenna element including the excitation element and the at least one non-excitation element is measured, and an input impedance of the array antenna apparatus is determined. Measuring step;
A second control voltage set different from the first control voltage set is set in the at least one variable reactance element, a current on each antenna element is measured, and an input impedance of the array antenna apparatus is measured. Steps,
Based on the measured current and input impedance, the current on each antenna element, the input impedance of the array antenna device, the input impedance of the excitation element itself, the excitation element and the non-excitation element Calculating structural parameters of the array antenna including impedances between the antenna elements using a relational expression between a coupling impedance between the antenna elements and an input impedance of each non-excited element loaded with the variable reactance element. And a method of measuring the electrical characteristics of the array antenna.   Measuring the current on each antenna element is to electromagnetically couple the detector of at least one magnetic field probe to the feed point or maximum current point of each antenna element using a near-field electromagnetic field measurement method. 2. The method for measuring the electrical characteristics of an array antenna according to claim 1, wherein a magnetic field generated by each of the antenna elements is measured in proximity to the antenna element, and a current is calculated based on the measured magnetic field. The structural parameters of the array antenna include a coupling impedance between the antenna elements, an input impedance of the excitation element itself, and an input impedance of the at least one non-excitation element itself loaded with the variable reactance element. The method for measuring electrical characteristics of an array antenna according to claim 1 or 2.

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