JP6042693B2 - Pointing vector measuring device - Google Patents

Description

  The present invention relates to a pointing vector measuring apparatus that measures a pointing vector.

  Pointing that indicates the flow of electromagnetic energy when specifying a part (noise source) that causes malfunction due to electromagnetic mutual interference in an electronic device, or specifying the directivity of an antenna or the propagation path of electromagnetic energy It is effective to measure vectors.

  This pointing vector is a vector obtained by the outer product of a magnetic field vector representing the strength / phase of the magnetic field and an electric field vector representing the strength / phase of the electric field. For this reason, when measuring a pointing vector, generally, a magnetic field and an electric field are individually measured, and the measurement result is processed.

  For example, a shielded loop coil or the like is used as a probe (sensor) for magnetic field measurement, and a monopole antenna or the like is used as a probe for electric field measurement.

  By the way, it is difficult to reduce the size of a probe for electric field measurement, or it is difficult to ensure a wide frequency band as compared with a magnetic field measurement probe. It is known that accurate measurement is difficult because the field is disturbed.

  On the other hand, instead of directly measuring the electric field, the potential distribution of the surface potential of the measurement target is obtained, the electric field component is estimated from the potential distribution, and the electric field estimation result and the magnetic field measurement probe measurement result are used. A method for calculating a pointing vector has been proposed (see, for example, Patent Document 1).

Japanese Patent No. 4635544

  However, with the conventional method described in Patent Document 1, there is a problem that the procedure of estimating the electric field component used when obtaining the electric field vector of an arbitrary space from the surface potential distribution obtained by measurement is complicated, There is a problem that it is necessary to use two types of probes (sensors) for potential measurement. Furthermore, the conventional method has a problem that it cannot be applied in a space where there is no object to be measured (surface potential measurement target).

  In order to solve the above-described problems, an object of the present invention is to provide a pointing vector measuring apparatus that measures a pointing vector with a simple configuration with high accuracy.

  In the pointing vector measurement apparatus of the present invention, a detection unit that detects a magnetic field around a measurement point is configured as follows using a point as a measurement target of the pointing vector as a measurement point.

  That is, three axes that pass through the measurement point of the pointing vector and are orthogonal to each other are defined as an X-axis, a Y-axis, and a Z-axis, respectively, two points facing each other on the Y axis and two points facing each other on the Z axis across the measurement point. An X-axis sensor, which is a magnetic field sensor for detecting a magnetic field in the X-axis direction, and two points facing each other on the Z-axis and two points facing each other on the X-axis across the measurement point A Y-axis sensor that is a magnetic field sensor that detects a magnetic field in the Y-axis direction and is disposed at (a total of four points), two points facing each other on the X-axis across two measurement points, and two points facing each other on the Y-axis A Z-axis sensor that is a magnetic field sensor that is disposed at (a total of four points) and detects a magnetic field in the Z-axis direction is provided.

  Then, the magnetic field component calculation means calculates the X-axis direction component from the detection result of the four X-axis sensors as the magnetic field component in each axis direction at the measurement point, and the Y-axis direction component from the detection result of the four Y-axis sensors. A component in the Z-axis direction is obtained from the detection results of the four Z-axis sensors.

  In this case, all the detection results of four sensors that detect the same axial direction may be used, or only the detection results of two sensors arranged on the same axis may be used. As a calculation method, a simple average value may be used, but when the distance from the measurement point to each sensor is different from each other, a weighted average value may be used according to the distance. .

  In addition, the electric field component calculation means calculates the X-axis direction component from the detection results of the Y-axis sensor and the Z-axis sensor as the electric field component in each axis direction at the measurement point, and the Y-axis from the detection results of the Z-axis sensor and the X-axis sensor. The component in the direction is obtained from the detection result of the X-axis sensor and the Y-axis sensor, and the component in the Z-axis direction is obtained using the relationship between the magnetic field and the electric field derived from the Maxwell equation.

  That is, according to the Maxwell equation, an electric field and a magnetic field can be described by a sine wave, and in a space where there is no current source (that is, the current density is zero), a magnetic field vector H representing the strength and phase of the magnetic field The electric field vector E representing the intensity and phase of the electric field has the relationship shown in (1), and the left side can be expressed by the equation (2).

  Therefore, a value obtained by partial differentiation of the magnetic field component Hx in the X axis direction in the Y axis direction and the Z axis direction, a value obtained by partial differentiation of the magnetic field component Hy in the X axis direction in the Z axis direction and the X axis direction, If a value obtained by partial differentiation of the magnetic field component Hz in the X-axis direction and the Y-axis direction is obtained, the electric field can be estimated from the measurement result of the magnetic field.

  For example, the value obtained by partial differentiation of the magnetic field component Hx in the X-axis direction in the Y-axis direction can be obtained using the detection result from the X-axis sensor arranged on the Y-axis and the distance from the measurement point to the X-axis sensor. Since the other partial differential values are the same, the electric field components in the respective axial directions at the measurement point can be obtained from the detection results of the twelve magnetic field sensors constituting the detection unit.

  Then, the pointing vector calculation means obtains the pointing vector at the measurement point by obtaining the outer product of the magnetic field vector that is the calculation result of the magnetic field component calculation means and the electric field vector that is the calculation result of the electric field component calculation means.

  As described above, according to the pointing vector measuring apparatus of the present invention, the pointing vector is obtained using only the measurement result of the magnetic field sensor without using the electric field sensor or the potential sensor, and the measured electromagnetic field is generated by the electric field sensor. Since it is not disturbed, it is possible to obtain a highly accurate measurement result, and furthermore, the electric field can be obtained by a simple process compared to the process of estimating the electric field from the detection result of the potential sensor. The load can be reduced.

It is a block diagram which shows the whole structure of a pointing vector measuring device. It is explanatory drawing which shows the structure of a detection part, and the positional relationship of a measurement point and a magnetic field sensor. It is a flowchart which shows the content of the measurement process which a control part performs. It is a graph which illustrates a measurement result.

Embodiments of the present invention will be described below with reference to the drawings.
<Overall configuration>
As shown in FIG. 1, a pointing vector measuring apparatus 1 to which the present invention is applied includes a detection unit 2 constituted by a plurality of magnetic field sensors, and a detection unit 2 movably held. A stage 3 for controlling the position inside the sensor, a sensor I / F unit 4 for inputting / outputting signals to / from the detection unit 2, and a detection signal output from the detection unit 2. The measurement unit 5 that is acquired via the sensor I / F unit 4 and executes signal processing of the acquired detection signal, and the signal processing that is executed by the measurement unit 5 while controlling the operation of the stage 3 and the measurement unit 5 The control part 6 which performs the measurement process which calculates | requires a pointing vector based on the result of is provided.

<Detector>
As shown in FIG. 2, the detection unit 2 includes a holding unit 20 made of a dielectric formed in a cube, and six sensor pairs 21 to 26 fixed in the vicinity of the centers of the six planes of the holding unit 20. It is constituted by. As the dielectric constituting the holding unit 20, for example, polystyrene foam can be used. However, the present invention is not limited to this, and any object having a dielectric constant substantially equal to the atmosphere may be used.

  Each of the sensor pairs 21 to 26 includes a pair of magnetic field sensors combined so as to detect magnetic fields in two directions orthogonal to each other. A magnetic field sensor consists of a shielded loop coil, for example. In FIG. 2, the sensor pairs 21 to 26 are represented by two disks that are orthogonal to each other, but these do not represent the actual shape, but detect a magnetic field in a direction orthogonal to the surface of the disk. Represents.

  In the following, the center of the cube that is the shape of the holding unit 20 is defined as a point P to be measured by the pointing vector (referred to as “measurement point”) P, and passes through the measurement point P, and the center of each outer surface of the cube. The three axes that are orthogonal to each other are called the X axis, the Y axis, and the Z axis.

  The sensor pairs 21 and 22 are fixed to the holding unit 20 so as to face each other on the X axis across the measurement point P and be disposed at a position where the distance from the measurement point P is Δx / 2. . Each of the pair of magnetic field sensors constituting the sensor pairs 21 and 22 detects one magnetic field component in the Y-axis direction (hereinafter referred to as Y-axis sensors 21Y and 22Y), and the other detects the magnetic field component in the Z-axis direction. The direction of detection (hereinafter referred to as Z-axis sensors 21Z and 22Z) is set.

  The sensor pairs 23 and 24 are fixed to the holding unit 20 so as to face each other on the Y axis with the measurement point P interposed therebetween and to be disposed at a position where the distance from the measurement point P is Δy / 2. . One of the pair of magnetic field sensors constituting the sensor pair 23, 24 detects a magnetic field component in the Z-axis direction (hereinafter referred to as Z-axis sensors 23Z, 24Z), and the other detects a magnetic field component in the X-axis direction. The direction of detection (hereinafter referred to as X-axis sensors 23X and 24X) is set.

  The sensor pairs 25 and 26 are fixed to the holding unit 20 so as to face each other on the Z axis with the measurement point P interposed therebetween and to be disposed at a position where the distance from the measurement point P is Δz / 2. . Each of the pair of magnetic field sensors constituting the sensor pair 25 and 26 detects one of the magnetic field components in the X-axis direction (hereinafter referred to as X-axis sensors 25X and 26X), and the other detects the magnetic field component in the Y-axis direction. The direction of detection (hereinafter referred to as Y-axis sensors 25Y and 26Y) is set.

  That is, if the coordinates of the measurement point P are represented by (i, j, k), the coordinates of the sensor pair 21 are (i + Δx / 2, j, k), and the coordinates of the sensor pair 22 are (i−Δx / 2). , J, k), the coordinates of the sensor pair 23 are (i, j + Δy / 2, k), the coordinates of the sensor pair 24 are (i, j−Δy / 2, k), and the coordinates of the sensor pair 25 are (i, j , K + Δz / 2), and the coordinates of the sensor pair 26 are (i, j, k−Δz / 2).

  However, in this embodiment, Δx, Δy, Δz that define the distance between the measurement point P and each of the sensor pairs 21 to 26 are all the same size, and the wavelength of the electromagnetic wave to be measured is λ. / 20 or so (Δx = Δy = Δz≈λ / 20). For example, when the measurement target is an electromagnetic wave in the 300 MHz band, Δx, Δy, Δz (that is, the length of one side of the holding unit 20) is about 5 cm.

<Sensor I / F part>
The sensor I / F unit 4 includes a switch that switches a magnetic field sensor that is a detection signal acquisition target according to a command from the control unit 6, an amplifier that amplifies the detection signal acquired through the switch, and the like. Note that the switch is configured to select any one of the sensor pairs 21 to 26 and simultaneously acquire detection signals from the two magnetic field sensors constituting the selected sensor pair.

<Measurement unit>
The measurement unit 5 includes a known spectrum analyzer that sequentially analyzes the frequency of detection signals output from the magnetic field sensor selected by the switch of the sensor I / F unit 4. The measurement unit 5 has two channels and is configured to process two detection signals supplied from the sensor I / F unit 4 in parallel.

<Control unit>
The control unit 6 includes a known microcomputer mainly composed of a CPU, a ROM, and a RAM. The control unit 6 drives the stage 3 and activates the measurement unit 5 to execute a measurement process of measuring a pointing vector.

<< Measurement process >>
The contents of the measurement process will be described with reference to the flowchart shown in FIG.
This process starts when a command is input via an operation unit (not shown).

  When this process is started, first, one of a plurality of detection points set in advance within the range of the three-dimensional space in which the detection unit 2 can be moved by the stage 3 is selected (S110), and the selected detection is performed. The stage is driven to move the detection unit 2 so that the point and the measurement point P of the detection unit 2 coincide (S120).

  Next, one of the sensor pairs 21 to 26 constituting the detection unit 2 is selected, and the sensor I / F unit 4 is set so that a detection signal is obtained from the pair of magnetic field sensors constituting the selected sensor pair. In this state, the measurement unit 5 is operated, and the result of signal processing of the detection signal from the measurement unit 5, that is, the two-direction magnetic field component measured by the selected sensor pair is acquired (S140). .

  Thereafter, it is determined whether or not the process of S140 has been executed for all sensor pairs (S150). If there is a sensor pair for which measurement has not been executed, the process returns to S130. On the other hand, if the processing of S140 is executed for all the sensor pairs, the magnetic field vector H representing the strength and phase of the magnetic field at the measurement point based on the measurement results of the magnetic field components obtained from the sensor pairs 21 to 26. Calculation (S160) and calculation of an electric field vector E representing the intensity and phase of the electric field at the measurement point (S170) are performed, and further, a pointing vector S is calculated (S180) using these magnetic field vector H and electric field vector E.

  The magnetic field vector H is calculated for the magnetic field component Hx in the X-axis direction by calculating the average value of the measurement results obtained by the X-axis sensors 23X, 24X, 25X, and 26X in the Y-axis direction as shown in the equation (3). As shown in the equation (4), the average value of the measurement results obtained by the Y-axis sensors 21Y, 22Y, 25Y, and 26Y is used, and the magnetic field component Hz in the Z-axis direction is expressed by the equation (5). As shown, the measurement is performed by obtaining an average value of the measurement results obtained by the Z-axis sensors 21Z, 22Z, 23Z, and 24Z.

  Here, although the average of four is calculated | required, you may make it obtain | require the average value of two sensors arrange | positioned on the same axis | shaft. For example, for the magnetic field component Hx in the X-axis direction, the average value of the measurement results of the X-axis sensors 23X and 24X located on the Y-axis (the average value of the first term and the second term on the right side of equation (3)), Or you may use the average value (average value of the 3rd term and the 4th term of the right side of a formula (3)) of the measurement result in X-axis sensors 25X and 26X located on a Z-axis.

  On the other hand, the electric field vector E is calculated for the electric field component Ex in the X-axis direction by Equation (6), for the electric field component Ey in the Y-axis direction by Equation (7), and for the electric field component Ez in the Z-axis direction by Equation (8). This is done using the relationship.

  The pointing vector S is calculated by obtaining the outer product of the magnetic field vector H and the electric field vector E as shown in the equation (9). Specifically, the components Sx, Sy, and Sz of the pointing vector S in each axial direction are calculated using equations (10) to (12). However, “*” is a symbol representing a conjugate complex number.

  When the calculation of the pointing vector S is completed, it is determined whether or not the processing of S120 to S180 has been executed for all detection points (S190). If there is an unprocessed detection point, the process returns to S110, and all detection points are detected. If the process has been executed, the measurement result is output (S200), and this process ends.

  For example, the measurement result may be output by simply writing the data in a predetermined memory or the like. For example, as shown in FIG. 4, the size and direction of the pointing vector for each detection point is determined by the length and inclination of the line. The displayed screen may be displayed on a display device (not shown). However, the X-axis, Y-axis, and Z-axis in FIG. 4 are different from those defined in FIG. 2 and are coordinate systems for determining the position of the region where the detection unit 2 can be moved by the stage 3.

<Effect>
As described above, the pointing vector measuring apparatus 1 obtains the pointing vector using only the measurement result of the magnetic field sensor without using the electric field sensor or the potential sensor.

  Therefore, according to the pointing vector measuring device 1, since the measured electromagnetic field is not disturbed by the electric field sensor, an accurate measurement result can be obtained, and the electric field is estimated from the detection result of the potential sensor. Since the electric field can be obtained from the measurement result of the magnetic field with a simple process compared to the process, the processing load of the apparatus can be reduced.

<Other embodiments>
Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and can be implemented in various modes without departing from the gist of the present invention.

For example, in the above-described embodiment, the cube 20 is used as the holding unit 20 constituting the detection unit 2, but may be a sphere or a rectangular parallelepiped.
In the above embodiment, the distances from the measurement point P to the sensor pairs 21 to 26 are all equal, but they may be different from each other. In this case, when calculating the magnetic field component in each axial direction, a weighted average value weighted according to the distance may be used instead of using a simple average value.

  In the above embodiment, the case where the measurement unit 5 has two channels for processing the detection signal has been described, but the number of channels may be one or three or more. In particular, when the measurement unit 5 has the same number of channels as the number of magnetic field sensors constituting the detection unit 2, the switch of the sensor I / F unit 4 is not necessary and may be omitted.

  In the above embodiment, a spectrum analyzer is used as the measurement unit 5, but a known network analyzer or the like may be used.

  DESCRIPTION OF SYMBOLS 1 ... Pointing vector measuring device 2 ... Detection part 3 ... Stage 4 ... Sensor I / F part 5 ... Measurement part 6 ... Control part 20 ... Holding part 21-26 ... Sensor pair 23X, 24X, 25X, 26X ... X-axis sensor 21Y , 22Y, 25Y, 26Y ... Y-axis sensor 21Z, 22Z, 23Z, 24Z ... Z-axis sensor

Claims (4)

Three axes that pass through a measurement point that is a measurement target of a pointing vector and that are orthogonal to each other are defined as an X axis, a Y axis, and a Z axis, and two points that are opposed to each other on the Y axis across the measurement point and the Z axis An X-axis sensor (23X, 24X, 25X, 26X) that is a magnetic field sensor for detecting a magnetic field in the X-axis direction is opposed to each of the two points facing each other on the Z-axis with the measurement point interposed therebetween. A Y-axis sensor (21Y, 22Y, 25Y, 26Y), which is a magnetic field sensor for detecting a magnetic field in the Y-axis direction, is placed on each of two points and two points facing each other on the X-axis with the measurement point in between. Z-axis sensors (21Z, 22Z, 23Z, 24Z) that are magnetic field sensors for detecting the magnetic field in the Z-axis direction at two points facing each other on the X-axis and two points facing each other on the Y-axis. Detecting portion configured by arranging and (2),
Regarding the magnetic field component in each axial direction at the measurement point, the X-axis direction component from the detection result of the X-axis sensor, the Y-axis direction component from the detection result of the Y-axis sensor, and the detection result of the Z-axis sensor Magnetic field component calculation means (5, S160) for obtaining a component in the Z-axis direction;
Regarding the electric field component in each axial direction at the measurement point, the component in the X axis direction from the detection results of the Y axis sensor and the Z axis sensor, and the component in the Y axis direction from the detection results of the Z axis sensor and the X axis sensor. An electric field component calculating means (5, S170) for obtaining a component in the Z-axis direction from the detection results of the X-axis sensor and the Y-axis sensor using the relationship between the magnetic field and the electric field derived from the Maxwell equation;
Pointing vector calculation means (5, S180) for obtaining a pointing vector at the measurement point by obtaining an outer product of a magnetic field vector as a calculation result in the magnetic field component calculation means and an electric field vector as a calculation result in the electric field component calculation means. )When,
Equipped with a,
The detection unit includes a holding unit (20) made of a dielectric formed in a cube,
The magnetic field sensor is held at the center of each plane of the holding unit so that the two points on the same axis where the magnetic field sensor is placed across the measurement point have the same distance to the measurement point. Poynting vector measuring apparatus characterized by being. The pointing vector measuring device according to claim 1 , further comprising position control means (3) for holding the detection unit movably and controlling a position of the detection unit in a three-dimensional space. The magnetic field component calculating means includes
The average value of the detection result of the magnetic field sensor that detects a magnetic field component of interest to the axial direction, according to claim 1 or claim 2, characterized in that said focusing axis direction of the magnetic field component in the measurement point Pointing vector measuring device. The electric field component calculation means includes
The first orthogonal direction, with one of the X, Y, and Z axes as the target axis direction, and two axial directions orthogonal to the target axis direction as the first orthogonal direction and the second orthogonal direction And a partial differential value in the second orthogonal direction with respect to the magnetic field component in the first orthogonal direction, and the magnetic field component in the second orthogonal direction based on the detection result of the magnetic field sensor that detects the magnetic field component in the second orthogonal direction. obtains a partial differential value of the first orthogonal direction, the difference between the partial differential value, in any one of claims 1 to 3, characterized in that said focusing axis direction of the electric field component in the measurement point The pointing vector measuring device described.