JP2018100904A - Electromagnetic field sensor, electromagnetic measuring system, and electromagnetic wave incoming direction inferring system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electromagnetic field sensor and an electromagnetic measuring system that can simultaneously measure electric fields and magnetic fields in the same position.SOLUTION: An electromagnetic field sensor unit 10 is configured of electromagnetic field sensors 11, 12 and 13 combined in mutually orthogonal three directions. A conductor loop 11a and a conductor loop 11b of an electromagnetic field sensor 11 are arranged side by side in the direction of a z axis within a single plane orthogonal to an x axis, and detects magnetic fields in the x axis and electric fields in the z axis. Similarly, a conductor loop 12a and a conductor loop 12b of the electromagnetic field sensor 12 are arranged side by side with the x axis within a single plane orthogonal to the y axis and detect magnetic fields in the direction of the y axis and electric fields in the direction of the x axis. A conductor loop 13a and a conductor loop 13b of an electromagnetic field sensor 13 are arranged side by side with the y axis direction, within a single plane orthogonal to the z axis, and detect magnetic fields in the direction of the z axis and electric fields in the direction of the y axis.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an electromagnetic field sensor, an electromagnetic field measurement system, and an electromagnetic wave arrival direction estimation system.

  In recent years, the environment of electromagnetic waves has become complicated due to the spread of electronic devices, and it has been required to search for the cause of electromagnetic interference by reducing unnecessary electromagnetic waves or estimating the position of the source of unnecessary electromagnetic waves. An electromagnetic field sensor for measuring an electric field and a magnetic field is used to evaluate the generation source of the unnecessary electromagnetic wave, the propagation direction of the unnecessary electromagnetic wave, and the like (see, for example, Patent Document 1).

  Patent Document 1 discloses an array antenna device as an electromagnetic field sensor. The array antenna apparatus has a configuration in which three antennas that respectively receive an electric field and a magnetic field intersect each other at a predetermined angle in space. Thereby, the electric field and magnetic field of three directions in space are measurable.

International Publication No. 2014/007191

  In the array antenna device described in Patent Document 1, an electric field measurement conductor and a magnetic field measurement conductor are used. The magnetic field measuring conductor is an antenna in which a conductor is formed in a substantially annular shape so that both ends of the conductor face each other. The electric field measuring conductor is a dipole antenna composed of a pair of conductors. In this array antenna apparatus, an electric field obtained from a potential difference between a pair of electric field measuring conductors and a magnetic field in a region surrounded by the magnetic field measuring conductors are measured. In this array antenna device, since the electric field measurement conductor and the magnetic field measurement conductor are close to each other, they are coupled to each other and affect both the electric field and the magnetic field to accurately measure both the electric field and the magnetic field. The problem is that it is difficult.

  In view of the above problems, an object of the present invention is to provide an electromagnetic field sensor and an electromagnetic field measurement system that can simultaneously measure an electric field and a magnetic field at the same position.

  In order to solve the above problems, an electromagnetic field sensor according to one embodiment of the present invention includes a pair of conductor loops arranged in a single plane.

  Thereby, the electric field and magnetic field in the same position can be measured simultaneously. Therefore, since the pointing vector at the same position can be measured, the electric field and the magnetic field at the position where the electromagnetic field sensor is arranged can be measured, and the propagation path and electromagnetic wave source of the unnecessary electromagnetic wave can be detected.

  The conductor loops of the pair of conductor loops have the same shape and may be arranged symmetrically.

  Thereby, the electric field and magnetic field in the center of an electromagnetic field sensor can be detected accurately.

  The conductor loops of the pair of conductor loops may be connected by a first resistor, and the electric field may be measured by detecting a first voltage that is a voltage across the first resistor. .

  Thus, the electric field can be easily measured by detecting the first voltage applied to both ends of the first resistor.

  Each conductor loop of the pair of conductor loops has a second resistor as a part of the conductor loop, and detects a second voltage that is a voltage across the second resistor to generate a magnetic field. You may measure.

  Thereby, the magnetic field can be easily measured by detecting the second voltage applied to both ends of the second resistor.

  The conductor loops of the pair of conductor loops are connected by a first resistor, and the second resistor is composed of a third resistor and a fourth resistor having the same resistance value and connected in series. The first resistor is connected between the third resistor and the fourth resistor, and an electric field is detected by detecting a first voltage that is a voltage across the first resistor. And the other end of the third resistor opposite to the one end of the third resistor to which the first resistor is connected, and one end of the fourth resistor to which the first resistor is connected The magnetic field may be measured by detecting the second voltage, which is a voltage between the other end of the fourth resistor on the opposite side.

  Thereby, the 1st voltage concerning both ends of the 1st resistance can be detected stably.

  Further, a first amplifier that amplifies and outputs the first voltage may be provided.

  Thereby, even if the value of the first voltage is very small, the first voltage can be amplified by the first amplifier, and the electric field can be accurately measured.

  Moreover, you may have 2nd amplifier which amplifies the said 2nd voltage detected in each conductor loop of a pair of said conductor loop, and outputs the average value of the amplified said 2nd voltage. .

  Thereby, even if the value of the second voltage is very small, the second voltage can be amplified by the second amplifier, and the magnetic field can be accurately measured.

  Further, the electromagnetic field sensor includes three sets of the electromagnetic field sensors, the single planes on which the three sets of electromagnetic field sensors are respectively arranged are orthogonal to each other, and the three sets of electromagnetic field sensors include the three sets of electromagnetic fields. You may cross in the center of each sensor.

  Thereby, an electric field and a magnetic field can be simultaneously measured at the same position in the three-dimensional space. Therefore, the propagation path of unnecessary electromagnetic waves and the electromagnetic wave source can be searched in three dimensions.

  An electromagnetic field measurement system according to an aspect of the present invention includes an electromagnetic field sensor having the above-described characteristics, and a signal processing unit that calculates a pointing vector from the electric field and the magnetic field detected by the electromagnetic field sensor. .

  Thereby, an electromagnetic field measurement system including an electromagnetic field sensor having the above-described characteristics can be obtained.

  An electromagnetic wave arrival direction estimation system according to an aspect of the present invention includes: an electromagnetic field sensor; and a signal processing unit that calculates a pointing vector from at least a part of the electric field and the magnetic field detected by the electromagnetic field sensor. The signal processing unit estimates an arrival direction of the electromagnetic wave from the calculated pointing vector.

  Accordingly, the electromagnetic field sensor having the above-described characteristics is provided, and the arrival direction of the electromagnetic wave can be estimated using the pointing vector calculated from at least a part of the electric field and the magnetic field detected by the electromagnetic field sensor.

  An electromagnetic wave arrival direction estimation system according to an aspect of the present invention includes: an electromagnetic field sensor; and a signal processing unit that calculates a pointing vector from the direction of the electric field and the direction of the magnetic field detected by the electromagnetic field sensor. The signal processing unit estimates an arrival direction of the electromagnetic wave from the calculated pointing vector.

  Accordingly, the electromagnetic field sensor having the above-described characteristics is provided, and the arrival direction of the electromagnetic wave can be estimated using the pointing vector calculated from the direction of the electric field and the magnetic field.

  The present invention can provide an electromagnetic field sensor and an electromagnetic field measurement system that can simultaneously measure an electric field and a magnetic field at the same position.

1 is a schematic configuration diagram of an electromagnetic field measurement system according to a first embodiment. 1 is a schematic configuration diagram of an electromagnetic field sensor according to a first embodiment. The figure which shows the measurement position of the electric field and magnetic field in the electromagnetic field sensor concerning Embodiment 1. Schematic configuration diagram of an electromagnetic field measurement system according to the second embodiment. Schematic configuration diagram of the first amplifier in the electromagnetic field measurement system according to the second embodiment. Schematic configuration diagram of a second amplifier in the electromagnetic field measurement system according to the second embodiment.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the drawings, the constituent elements denoted by the same reference numerals indicate the same or similar constituent elements.

  Further, the embodiment described below shows a preferred specific example of the present invention. The numerical values, shapes, materials, constituent elements, arrangement positions of the constituent elements, connection forms, steps, order of steps, and the like shown in the following embodiments are merely examples, and are not intended to limit the present invention. In addition, among the constituent elements in the following embodiments, constituent elements that are not described in the independent claims showing the highest concept of the present invention are described as optional constituent elements that constitute a more desirable form.

(Embodiment 1)
[Configuration of electromagnetic field measurement system]
First, the configuration of the electromagnetic field measurement system 1 having the electromagnetic field sensor unit 10 will be described with reference to FIG. FIG. 1 is a schematic configuration diagram of an electromagnetic field measurement system 1 according to the present embodiment.

  As shown in FIG. 1, the electromagnetic field measurement system 1 includes an electromagnetic field sensor unit 10, a signal processing unit 20, and a wiring 30 that connects the electromagnetic field sensor unit 10 and the signal processing unit 20.

  The electromagnetic field sensor unit 10 includes electromagnetic field sensors 11, 12, and 13 combined in three orthogonal directions. As shown in FIG. 1, the electromagnetic field sensor 11 has a conductor loop 13a and a conductor loop 13b. The conductor loop 11a and the conductor loop 11b are arranged side by side in the z-axis direction in a single plane orthogonal to the x-axis shown in FIG. Thereby, the electromagnetic field sensor 11 detects a magnetic field in the x-axis direction and an electric field in the z-axis direction. Similarly, the electromagnetic field sensor 12 includes a conductor loop 12a and a conductor loop 12b as shown in FIG. The conductor loop 12a and the conductor loop 12b are arranged side by side in the x-axis direction in a single plane orthogonal to the y-axis shown in FIG. Thereby, the electromagnetic field sensor 12 detects a magnetic field in the y-axis direction and an electric field in the x-axis direction. As shown in FIG. 1, the electromagnetic field sensor 13 includes a conductor loop 13a and a conductor loop 13b. The conductor loop 13a and the conductor loop 13b are arranged side by side in the y-axis direction in a single plane orthogonal to the z-axis shown in FIG. Thereby, the electromagnetic field sensor 13 detects a magnetic field in the z-axis direction and an electric field in the y-axis direction.

  A circuit box 111 is disposed at a position where the electromagnetic field sensors 11, 12 and 13 intersect. As will be described later, the circuit box 111 is provided with resistors, wiring, and output terminals that constitute part of the electromagnetic field sensors 11, 12, and 13.

  The electromagnetic field sensor unit 10 may be one in which the electromagnetic field sensors 11, 12 and 13 are used alone, or may be a combination of two or three as described above.

  The signal processing unit 20 calculates a pointing vector from the electric field and magnetic field detected by the electromagnetic field sensor unit 10. The signal processing unit 20 includes, for example, an AD conversion unit (not shown) that converts an analog signal into a digital value, and an arithmetic unit (not shown). The arithmetic unit is, for example, an MPU (Micro Processing Unit). The arithmetic unit is not limited to the MPU, and may be another arithmetic circuit.

  The signal processing unit 20 samples the electric field and magnetic field (analog values) measured by the electromagnetic field sensor unit 10 by the AD conversion unit and converts them to digital values. Then, using the electric field and magnetic field converted into digital values, the calculation unit calculates a pointing vector, which will be described later. Since the signal processing unit 20 has a general configuration, detailed description thereof is omitted. The configuration of the signal processing unit 20 is not limited to the configuration described above, and may be another configuration.

  The wiring 30 is a wiring that connects the electromagnetic field sensors 11, 12, and 13 in the electromagnetic field sensor unit 10 to the signal processing unit 20. More specifically, the wiring 30 is wired from the circuit box 111 of the electromagnetic field sensor unit 10 to the signal processing unit 20. The electric field signal and magnetic field signal detected by the electromagnetic field sensors 11, 12, and 13 are output to the signal processing unit 20 via the wiring 30. The wiring 30 may be provided for each of the electromagnetic field sensors 11, 12, and 13, or one wiring 30 may be provided so as to be connected to any of the electromagnetic field sensors 11, 12, and 13. Further, instead of the wiring 30, an electric field and a magnetic field detected by the electromagnetic field sensor unit 10 may be output to the signal processing unit 20 wirelessly.

[Configuration of electromagnetic field sensor]
Here, details of the configuration of the electromagnetic field sensors 11, 12 and 13 will be described with reference to FIG. FIG. 2 is a schematic configuration diagram of the electromagnetic field sensors 11, 12 and 13 according to the present embodiment. In addition, since the structure of the electromagnetic field sensors 11, 12, and 13 is the same, below, the electromagnetic field sensor 13 is demonstrated as an example.

  As described above, the electromagnetic field sensor 13 includes the conductor loop 13a and the conductor loop 13b.

  As shown in FIG. 2, the conductor loop 13a has a conducting wire 130a, a resistor 132a, and a resistor 133a. The resistor 132a and the resistor 133a are provided in series between both ends of the conducting wire 130a so as to connect both ends of the conducting wire 130a.

  Specifically, the lead wire 130a is formed of a copper wire having a diameter of 1 mm in a substantially annular shape that is long in the x-axis direction as shown in FIG. Here, the term “substantially annular” refers to a shape that is not a completely bound ring but has a ring shape as a whole, but is partially open. The long side of the conducting wire 130a is 105 mm, for example, and the short side is 50 mm, for example. Moreover, both ends of the conducting wire 130a are opposed in the vicinity of the center of one of the two long sides. The space | interval of the both ends which the conducting wire 130a opposes is 5 mm, for example. And resistance 132a and 133a are arrange | positioned in series between the both ends which oppose.

  Similarly, the conductor loop 13b has a conducting wire 130b and resistors 132b and 133b. The resistor 132b and the resistor 133b are provided in series between both ends of the conducting wire 130b so as to connect both ends of the conducting wire 130b. That is, as shown in FIG. 2, the conducting wire 130 b is formed in a substantially annular shape that is long in the x-axis direction, and both ends are opposed in the vicinity of the center of one of the two long sides. A resistor 132b and a resistor 133b are arranged in series between the opposite ends.

  Further, the conductor loop 13a and the conductor loop 13b have a symmetric configuration. That is, the conducting wires 130a and 130b have the same shape, and are arranged point-symmetrically and line-symmetrically with a distance of 5 mm, for example. The resistors 132a, 132b, 133a, and 133b have the same shape, and are arranged point-symmetrically and line-symmetrically. The resistance values of the resistors 132a, 132b, 133a, and 133b are the same, for example, 500Ω.

  The conducting wires 130a and 130b do not have to have the same shape, and need not be arranged point-symmetrically and line-symmetrically. Moreover, the conducting wires 130a and 130b may be arranged in either point symmetry or line symmetry. The resistors 132a, 132b, 133a, and 133b do not have to have the same shape, and need not be arranged point-symmetrically and line-symmetrically. In addition, the resistors 132a, 132b, 133a, and 133b may be arranged in either point symmetry or line symmetry. Further, the resistance values of the resistors 132a, 132b, 133a, and 133b may not be the same.

  A resistor 135 is connected between the resistors 132a and 133a of the conductor loop 13a and between the resistors 132b and 133b of the conductor loop 13b. That is, the conductor loop 13a and the conductor loop 13b are connected by the resistor 135. The resistor 135 is 1 MΩ, for example. The resistors 132 a, 132 b, 133 a, 133 b and 135 are arranged inside the circuit box 111.

  In the present embodiment, the resistor 135 corresponds to a first resistor. The sum of the resistors 132a and 133a and the sum of the resistors 132b and 133b correspond to second resistors, respectively. The resistors 132a and 133a correspond to third resistors, respectively. The resistors 132b and 133b correspond to fourth resistors, respectively.

  Further, a terminal A is provided between the conducting wire 130a and the resistor 132a, and a terminal A 'is provided between the conducting wire 130a and the resistor 133a. That is, in the resistor 132a, the terminal A is provided on the other end side opposite to the one end to which the resistor 135 is connected. Further, in the resistor 133a, a terminal A 'is provided on the other end side opposite to one end to which the resistor 135 is connected. By detecting the voltage between the terminal A and the terminal A ′, the voltage applied to the resistors 132a and 133a can be detected. Thereby, the magnetic field passing perpendicularly to the loop surface of the conductor loop 13a, that is, the magnetic field crossing the conductor loop 13a is measured. The loop surface of the conductor loop 13a refers to a plane formed by the conductor loop 13a.

  Similarly, a terminal B is provided between the conducting wire 130b and the resistor 132b, and a terminal B 'is provided between the conducting wire 130b and the resistor 133b. That is, in the resistor 132b, the terminal B is provided on the other end side opposite to the one end to which the resistor 135 is connected. Further, in the resistor 133b, a terminal B 'is provided on the other end side opposite to the one end to which the resistor 135 is connected. By detecting the voltage between the terminal B and the terminal B ', the voltage applied to the resistors 132b and 133b can be detected. Thereby, the magnetic field which passes perpendicularly to the loop surface of the conductor loop 13b is measured.

  Further, a terminal C and a terminal C ′ are provided at both ends of the resistor 135, respectively. By detecting the voltage between the terminal C and the terminal C ′, the voltage applied to the resistor 135 can be detected. Thereby, the electric field between the conductor loops 13a and 13b is measured.

  In the present embodiment, the voltage between the terminal C and the terminal C ′ corresponds to the first voltage. Further, the voltage between the terminal A and the terminal A ′ and the voltage between the terminal B and the terminal B ′ correspond to the second voltage, respectively.

  Since the electromagnetic field sensors 11 and 12 have the same configuration as that of the electromagnetic field sensor 13, detailed description thereof is omitted.

  With such a configuration, the electromagnetic field sensor unit 10 can measure an electromagnetic field having a frequency of about 150 kHz to 30 MHz, for example. Note that the frequency band of the detectable electromagnetic field may be changed by changing the size of the conductive wires 130a and 130b and the values of the resistors 132a, 132b, 133a, 133b, and 135 described above.

  The electromagnetic field sensors 11, 12, and 13 may have the same configuration as described above, or only two of the electromagnetic field sensors 11, 12, and 13 may have the same configuration. Further, all of the electromagnetic field sensors 11, 12, and 13 may have different configurations.

[Principle of electromagnetic field measurement]
Next, the principle of electromagnetic field measurement by the electromagnetic field measurement system 1 will be described with reference to FIG. FIG. 3 is a diagram showing measurement positions of the electric field and the magnetic field in the electromagnetic field sensors 11, 12 and 13 according to the present embodiment, and (a) is a diagram showing measurement positions of the electric field and the magnetic field in the electromagnetic field sensor 13. (B) is a figure which shows the coordinate axis in the electromagnetic field sensor 13 shown to (a), and the direction of the electric field in the electromagnetic field sensor 13, and a magnetic field.

  Since the electric field is a potential difference per unit length between two conductors, the electromagnetic field measurement system 1 measures a potential difference between the conductor loop 13a and the conductor loop 13b, which are the two conductors in the electromagnetic field sensor 13.

Specifically, in the electromagnetic field sensor 13, as shown in FIG. 3A, the electric field detects the potential difference generated between the center P of the electromagnetic field sensor 13, that is, between the conductor loop 13a and the conductor loop 13b. To measure. That is, in the electromagnetic field sensor 13, the electric field is obtained by detecting and calculating (calibrating) the voltage applied to the resistor 135. More specifically, the electromagnetic field sensor 13 detects a voltage between the terminal C and the terminal C ′. And the calibration mentioned later is performed using the detected voltage. As a result, the electromagnetic field sensor 13 can measure the electric field E _y in the y-axis direction as shown in FIG.

  The resistor 135 is provided to facilitate the detection of the voltage between the conductor loop 13a and the conductor loop 13b, and can detect the voltage between the conductor loop 13a and the conductor loop 13b. In this case, the resistor 135 may not be provided.

Similarly to the electromagnetic field sensor 13, the electromagnetic field sensors 11 and 12 measure an electric field in the z-axis direction and an electric field in the x-axis direction, respectively. By combining the electromagnetic field sensors 11, 12 and 13, the electric fields E _x , E _y and E _z in the x-axis direction, the y-axis direction and the z-axis direction can be measured simultaneously. In addition, the electromagnetic field sensors 11, 12 and 13 have the same configuration and are crossed at their centers so that the planes on which the conductor loops 13a and 13b are arranged are orthogonal to each other. E _x , E _y and E _z can be measured simultaneously.

  In the electromagnetic field measurement system 1, the magnetic field interlinking with the respective loop surfaces of the conductor loop 13a and the conductor loop 13b, which are the two conductors in the electromagnetic field sensor 13, and the voltages of the conductor loop 13a and the conductor loop 13b are measured. To measure. Here, the magnetic field interlinking with the loop surface means a magnetic flux perpendicularly intersecting the loop surface, that is, a magnetic field perpendicularly intersecting the loop surfaces of the conductor loop 13a and the conductor loop 13b integrated (averaged) by the loop area. . The magnetic field interlinking with the loop surface is sometimes referred to as the magnetic field at the center of the loop.

  Specifically, in the electromagnetic field sensor 13, as shown in FIG. 3A, the voltage between the terminals of each of the conductor loop 13a and the conductor loop 13b is detected, and the conductor loop 13a and the conductor loop 13b are detected. Calculate (calibrate) the magnetic field linked to each loop surface. And the magnetic field of the center of the electromagnetic field sensor 13 is measurable by averaging the magnetic field linked to each loop surface of the conductor loop 13a and the conductor loop 13b. In the electromagnetic field sensor 13, the magnetic field in the electromagnetic field sensor 13 may be calculated from the average value of the voltages detected between the terminals of the conductor loop 13a and the conductor loop 13b.

  In the electromagnetic field sensor 13, the magnetic field linked to the loop surface of the conductor loop 13a is obtained by detecting and calculating the voltage applied to the resistors 132a and 133a. The magnetic field interlinking with the loop surface of the conductor loop 13b is obtained by detecting and calculating the voltage applied to the resistors 132b and 133b. More specifically, the magnetic field linked to the loop surface of the conductor loop 13a is obtained by detecting and calculating the voltage between the terminal A and the terminal A '. The magnetic field interlinking with the loop surface of the conductor loop 13b is obtained by detecting and calculating the voltage between the terminal B and the terminal B '. Then, the average of the voltage between the terminal A and the terminal A ′ and the voltage between the terminal B and the terminal B ′ is calculated. That is, by performing the calibration described later using the voltage between the terminal A and the terminal A ′ and the voltage between the terminal B and the terminal B ′, the conductor loop between the conductor loop 13a and the conductor loop 13b. A magnetic field at a point P at an equal distance from 13a and the conductor loop 13b, that is, a magnetic field in the electromagnetic field sensor 13 is obtained.

Thus, the electromagnetic field sensor 13 can measure the magnetic field H _z in the z-axis direction as shown in (b) of FIG.

  The resistors 132a and 133a are provided to facilitate detection of a voltage for measuring a magnetic field linked to the loop surface of the conductor loop 13a. The resistors 132b and 133b are resistors provided to make it easy to detect a voltage for measuring a magnetic field linked to the loop surface of the conductor loop 13b. The resistors 132a, 133a, 132b, and 133b may not be provided as long as the voltage for measuring the magnetic field linked to the loop surfaces of the conductor loop 13a and the conductor loop 13b can be detected.

Similarly to the electromagnetic field sensor 13, the electromagnetic field sensors 11 and 12 measure the magnetic field in the x-axis direction and the magnetic field in the y-axis direction, respectively. By combining the electromagnetic field sensors 11, 12 and 13, the magnetic fields H _x , H _y and H _z in the x-axis direction, the y-axis direction and the z-axis direction can be measured simultaneously. Further, the electromagnetic field sensors 11, 12 and 13 have the same configuration and are combined at their center positions, so that the magnetic fields H _x , H _y and H _z at the same position can be measured simultaneously.

  Here, an electromagnetic field calibration procedure will be described.

  First, a reference electric field or a reference magnetic field is applied to each of the electromagnetic field sensors 11, 12, and 13 in order to detect a voltage generated between the loop terminals in each of the electromagnetic field sensors 11, 12, and 13. In each of the electromagnetic field sensors 11, 12, and 13, a voltage generated between the loop terminals is measured. Thereby, for each of the electromagnetic field sensors 11, 12 and 13, the relationship between the electric field or the magnetic field and the detected voltage, that is, the antenna coefficient is obtained.

  Then, the voltage actually detected in each of the electromagnetic field sensors 11, 12 and 13 is multiplied by the antenna coefficient to calculate the electric field or magnetic field measured by the electromagnetic field sensors 11, 12 and 13.

When the detected voltage includes a voltage of a component that should not be output, crosstalk has occurred between the components of the electromagnetic field sensors 11, 12, and 13. The component means an electric field (E _x , E _y , E _z ) and a magnetic field (H _x , H _y , H _z ) corresponding to each of the x-axis direction, the y-axis direction, and the z-axis direction. The performance of each electromagnetic field sensor can be evaluated by detecting the presence / absence of crosstalk and the component in which crosstalk occurs.

In addition, when an electric field (E _x , E _y , E _z ) and a magnetic field (H _x , H _y , H _z ) in each of the x-axis direction, the y-axis direction, and the z-axis direction are applied, The six component output voltages corresponding to the magnetic field can be represented in the form of a 6 × 6 matrix. By using this matrix, the six electromagnetic field components detected by the electromagnetic field sensors 11, 12 and 13 can be accurately obtained from the actually measured output voltages of the six components.

  Moreover, since the electromagnetic field measurement system 1 can simultaneously measure the electric field and the magnetic field at the same position as described above, the signal processing unit 20 may calculate the pointing vector using the measured electric field and magnetic field. . The pointing vector is an index indicating the flow of the energy density of the electromagnetic field, and the direction of the pointing vector represents the moving direction of the electromagnetic field energy.

磁界ベクトルを

とすると、以下の（式３）のように、電界ベクトルと磁界ベクトルとの外積で表すことができる。 Pointing vector is the electric field vector

Magnetic field vector

Then, it can be expressed by an outer product of an electric field vector and a magnetic field vector as in the following (Equation 3).

  More specifically, the electric field vector and the magnetic field vector change with time, and a pointing vector (instantaneous pointing vector) at a certain moment (time t) is expressed by the following (Equation 4).

  Here, E (t) and H (t) indicate an electric field vector and a magnetic field vector at time t, respectively.

  With this instantaneous pointing vector, it is possible to detect the electromagnetic field energy and the direction of movement of the electromagnetic field energy at a certain time t.

  Further, the time average of the pointing vectors can be measured by measuring the instantaneous pointing vector for a certain time and calculating the average value. The time average of the pointing vector indicates the propagation direction of energy radiated from the electromagnetic wave source. Therefore, the propagation direction of energy radiated from the electromagnetic wave source can be detected by calculating the pointing vector.

  The calculation of the pointing vector may be performed on the time axis as described above, or may be performed on the frequency axis.

By performing the above calculation of the pointing vector in the signal processing unit 20, the electromagnetic field measurement system 1 can measure the electric field and magnetic field at the position of the electromagnetic field sensor unit 10 at a certain time t. Further, the propagation path of unnecessary electromagnetic waves and the electromagnetic wave source may be estimated by the signal processing unit 20 from the measurement result of the electric field and the magnetic field at the position where the electromagnetic field sensor unit 10 is disposed. For example, for a plane wave having orthogonal polarization, the angle of the xy plane can be detected from the magnetic field H _{x in} the x-axis direction, the magnetic field H _{y in} the y-axis direction, and the electric field E _{z in the} z-axis direction. Similarly, it is possible to detect the angle of the y-z plane from the magnetic field in the y-axis direction H _y, z-axis direction magnetic field H _z and the x-axis direction of the electric field E _x. field H _z in the z-axis _direction, it is possible to detect the angle of the z-x plane from the electric field E _y of the magnetic field H _x and y-axis direction of the x-axis direction. Further, the position of the electromagnetic wave source may be estimated by combining the angles of the xy plane, the yz plane, and the zx plane.

The signal processing unit 20 may calculate a pointing vector from the direction of the electric field and magnetic field detected by the electromagnetic field sensor unit 10. For example, the calibration of the electric and magnetic fields described above, the absolute value _E x of the electric _field, E y, _{E z} and the magnetic field of the absolute values _{H x, H y, H z} instead field relative value _{aE x, aE y, aE z} (A is a coefficient) and relative values bH _x , bH _y , and bH _z (b is a coefficient) of the magnetic field may be used for calculation. Accordingly, at least angle information related to the position of the electromagnetic wave source can be detected, so that the direction of the electromagnetic wave source can be estimated.

  Thus, the electromagnetic field sensor unit 10 and the signal processing unit 20 may be used as an electromagnetic wave arrival direction estimation system that estimates the arrival direction of an electromagnetic wave.

  In addition, since the electric current which flows through the conductor loops 13a and 13b by the change of an electromagnetic field is very small, the voltage for electric field measurement detected in the electromagnetic field sensor part 10 and the voltage for magnetic field measurement are very small. Therefore, these voltages detected by the electromagnetic field sensors 11, 12 and 13 may be amplified by an amplifier and output to the signal processing unit 20.

[Effects]
As described above, according to the electromagnetic field sensor and the electromagnetic field measurement system according to the present embodiment, the electric field and the magnetic field at the same position can be detected, so that the pointing vector can be measured. Therefore, the electric field and magnetic field at the position where the electromagnetic field sensor is disposed can be measured. Furthermore, the propagation path of unnecessary electromagnetic waves and the electromagnetic wave source may be estimated from the result of measuring the electric field and magnetic field at the position where the electromagnetic field sensor is arranged by the signal processing unit 20.

(Embodiment 2)
Next, the electromagnetic field measurement system 2 according to the second exemplary embodiment will be described with reference to FIGS. FIG. 4 is a schematic configuration diagram of the electromagnetic field measurement system 2 according to the present embodiment. FIG. 5 is a schematic configuration diagram of the first amplifier 31 in the electromagnetic field measurement system 2 according to the present embodiment. FIG. 6 is a schematic configuration diagram of the second amplifier 32 in the electromagnetic field measurement system 2 according to the present embodiment.

  The electromagnetic field measurement system 2 according to the present embodiment is different from the electromagnetic field measurement system 1 shown in the first embodiment in that the first amplifier 31 and the first amplifier 31 are disposed between the electromagnetic field sensor unit 10 and the signal processing unit 20. The second amplifier 32 is provided.

  As shown in FIG. 4, the electromagnetic field measurement system 2 includes an electromagnetic field sensor unit 10, a signal processing unit 20, and a wiring 30, similar to the electromagnetic field measurement system 1 described in the first embodiment. The wiring 30 is provided with a first amplifier 31 and a second amplifier 32. The basic configuration of the electromagnetic field sensor unit 10 and the signal processing unit 20 is the same as that of the electromagnetic field sensor unit 10 and the signal processing unit 20 in the electromagnetic field measurement system 1 shown in the first embodiment. Description is omitted.

  The first amplifier 31 is an electric field preamplifier for amplifying and outputting a voltage for measuring an electric field from the electromagnetic field sensor unit 10. That is, the first amplifier 31 is connected to the terminals C and C ′. As shown in FIG. 5, the first amplifier 31 includes an amplifier 34a to which the terminal C is connected, an amplifier 34b to which the terminal C ′ is connected, and a resistor connected to the ground between the terminal C and the amplifier 34a. 35a, a resistor 35b connected to the ground between the terminal C ′ and the amplifier 34b, and an amplifier 36 to which the voltages output from the amplifiers 34 and 34b are input.

The amplifier 36 amplifies and outputs the difference between the voltage obtained by amplifying the voltage V _C at the terminal C by the amplifier 34a and the voltage obtained by amplifying the voltage V _{C ′} at the terminal _{C ′} by the amplifier 34b. Therefore, the first amplifier 31 outputs a voltage proportional to the potential difference V _C −V _{C ′} between the terminal C and the terminal C ′. Using the voltage output from the first amplifier 31, the electric field between the conductor loops 13a and 13b can be calculated. Accordingly, even when the value of the 'voltage V _C at _the' voltage V _C and the terminal C in the terminal C is very small, it is possible to measure the electric field accurately by the electromagnetic field sensor unit 10.

  The second amplifier 32 is a magnetic field preamplifier for amplifying and outputting a voltage for measuring a magnetic field from the electromagnetic field sensor unit 10. The second amplifier 32 is connected to the terminals A and A ′ and the terminals B and B ′. As shown in FIG. 6, the second amplifier 32 has an amplifier 37a to which terminals A and A ′ are connected, an amplifier 37b to which terminals B and B ′ are connected, and voltages output from the amplifiers 37a and 37b. And an input amplifier 38.

The amplifier 37a amplifies and outputs the difference V _A −V _{A ′} between the voltage V _A at the terminal A and the voltage V _{A ′} at the terminal A ′. The amplifier 37b amplifies and outputs the difference V _B −V _{B ′} between the voltage V _B at the terminal B and the voltage V _{B ′} at the terminal B ′. The amplifier 38 adds and outputs the voltage obtained by amplifying the potential difference V _A −V _{A ′} in the amplifier 37a and the voltage obtained by amplifying the potential difference V _B −V _{B ′} in the amplifier 37b. The second amplifier 32 outputs an average value of voltages proportional to the potential difference V _A −V _{A ′} between the terminals _A and _{A ′} and the potential difference V _B −V _{B ′} between the terminals B and B ′.

By calculating using the voltage output from the second amplifier 32, the average of the magnetic field detected in the conductor loop 13a and the magnetic field detected in the conductor loop 13b, that is, between the conductor loops 13a and 13b. The magnetic field can be calculated. Thus, even when the values of the voltage V _{A at} the terminal A, the voltage V _{A ′ at the} terminal _{A ′,} the voltage V _{B at the} terminal B, and the voltage V _{B ′ at} the terminal B ′ are very small, the electromagnetic field sensor unit 10 can measure the magnetic field with high accuracy.

  The first amplifier 31 and the second amplifier 32 may be provided so as to be located at the center of each of the electromagnetic field sensors 11, 12, and 13. When the first amplifier and the second amplifier are not positioned at the center of the electromagnetic field sensors 11, 12, and 13, the length and the routing position of the wiring 30 from the electromagnetic field sensors 11, 12, and 13 to the amplifier become asymmetric. This is because the electromagnetic field in each loop of the electromagnetic field sensors 11, 12 and 13 may be disturbed. Since the first amplifier and the second amplifier are provided so as to be positioned at the center of the electromagnetic field sensors 11, 12 and 13, the symmetry of the electric field and magnetic field of the two loops can be maintained in each electromagnetic wave sensor. Electromagnetic field measurement accuracy can be improved. For example, the first amplifier 31 and the second amplifier 32 may be provided inside the circuit box 111 of the electromagnetic field sensor unit 10.

(Other embodiments)
As mentioned above, although the electromagnetic field sensor and electromagnetic field measurement system concerning this invention were demonstrated based on embodiment, this invention is not limited to embodiment. Embodiments obtained by subjecting the embodiments to modifications conceivable by those skilled in the art and other embodiments realized by arbitrarily combining components in the embodiments are also included in the present invention.

  For example, in the above-described embodiment, the electromagnetic field sensor unit has a configuration in which three electromagnetic field sensors are combined so that the single planes on which the electromagnetic field sensors are arranged are orthogonal to each other. May be composed of one electromagnetic field sensor or may be composed of two electromagnetic field sensors.

  In the above-described embodiment, the conductor loop constituting the electromagnetic field sensor is rectangular. However, the conductor loop is not limited to the rectangular shape, and may be another shape such as a circular shape. Moreover, the shape of a pair of conductor loop which comprises an electromagnetic field sensor may be the same shape, and a different shape may be sufficient as it. Further, the arrangement of the pair of conductor loops may be arranged in any of point symmetry and line symmetry, point symmetry and line symmetry, or another arrangement.

  The plurality of resistors constituting a part of the pair of conductor loops may have the same resistance value or different resistance values. Further, the resistance connecting the pair of conductor loops may be the same resistance value as the resistance constituting a part of the conductor loop, or may be a different resistance value.

  Further, the electromagnetic field measurement system may or may not include a first amplifier for amplifying a voltage between a pair of conductor loops detected for measuring an electric field. The electromagnetic field measurement system may or may not include a second amplifier for amplifying a voltage detected for measuring the magnetic field. In addition, the first amplifier and the second amplifier may be provided at the center of the electromagnetic field sensor unit or may be provided at other positions.

  In the embodiment described above, wiring is provided from the electromagnetic field sensor to the signal processing unit, and the electric field and magnetic field detected by the electromagnetic field sensor unit are output to the signal processing unit through the wiring. Then, the electric field and magnetic field detected by the electromagnetic field sensor may be output wirelessly to the signal processing unit.

  In the electromagnetic field measurement system, the signal processing unit may include an AD conversion unit and a calculation unit as described above, or may have another configuration. The signal processing unit may further include a storage unit that stores the measured electric field and magnetic field and the calculated pointing vector.

  The electromagnetic field sensor and the electromagnetic field measurement system according to the present invention are useful as an electromagnetic field sensor and an electromagnetic field measurement system that are used in railways, cars, and the like that need to detect electromagnetic waves having a broadband frequency.

DESCRIPTION OF SYMBOLS 1, 2 Electromagnetic field measurement system 10 Electromagnetic field sensor part 11, 12, 13 Electromagnetic field sensor 11a, 11b, 12a, 12b, 13a, 13b Conductor loop 20 Signal processing part 30 Wiring 31 1st amplifier 32 2nd amplifier 34a , 34b, 36, 37a, 37b, 38 Amplifier 35a, 35b Resistor 111 Circuit box 130a, 130b Conductor 132a, 132b Resistor (second resistor, third resistor)
133a, 133b resistors (second resistor, fourth resistor)
135 Resistance (first resistance)

Claims (11)

An electromagnetic field sensor comprising a pair of conductor loops arranged in a single plane. The electromagnetic field sensor according to claim 1, wherein the conductor loops of the pair of conductor loops have the same shape and are arranged symmetrically. Each conductor loop of the pair of conductor loops is connected by a first resistor,
The electromagnetic field sensor according to claim 1, wherein the electric field is measured by detecting a first voltage that is a voltage across the first resistor. Each conductor loop of the pair of conductor loops has a second resistance as a part of the conductor loop,
The electromagnetic field sensor according to claim 1, wherein a magnetic field is measured by detecting a second voltage that is a voltage across the second resistor. Each conductor loop of the pair of conductor loops is connected by a first resistor,
The second resistor is composed of a third resistor and a fourth resistor having the same resistance value and connected in series,
The first resistor is connected between the third resistor and the fourth resistor,
Measuring the electric field by detecting a first voltage that is the voltage across the first resistor;
The other end of the third resistor opposite to one end of the third resistor connected to the first resistor, and the other end of the fourth resistor connected to the first resistor. The electromagnetic field sensor according to claim 4, wherein the magnetic field is measured by detecting the second voltage, which is a voltage between the other end of the fourth resistor. The electromagnetic field sensor according to claim 3, further comprising: a first amplifier that amplifies and outputs the first voltage. The second amplifier that amplifies the second voltage detected in each conductor loop of the pair of conductor loops and outputs an average value of the amplified second voltage. The electromagnetic field sensor described. 3 sets of the electromagnetic field sensors,
2. The single plane on which the three sets of electromagnetic field sensors are respectively arranged is orthogonal to each other, and the three sets of electromagnetic field sensors intersect at the center of each of the three sets of electromagnetic field sensors. The electromagnetic field sensor of any one of -7. The electromagnetic field sensor according to any one of claims 1 to 8,
An electromagnetic field measurement system comprising: a signal processing unit that calculates a pointing vector from the electric field and the magnetic field detected by the electromagnetic field sensor. The electromagnetic field sensor according to any one of claims 1 to 8,
A signal processing unit that calculates a pointing vector from at least a part of the electric field and the magnetic field detected by the electromagnetic field sensor,
The signal processing unit estimates an arrival direction of an electromagnetic wave from the calculated pointing vector. The electromagnetic field sensor according to any one of claims 1 to 8,
A signal processing unit that calculates a pointing vector from the direction of the electric field and the direction of the magnetic field detected by the electromagnetic field sensor;
The signal processing unit estimates an arrival direction of an electromagnetic wave from the calculated pointing vector.

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