JP2956718B2 - Electromagnetic field distribution measuring device, electromagnetic wave source analysis system, and electromagnetic field analysis system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for measuring an electromagnetic field distribution of an electromagnetic wave radiated from an electromagnetic wave source body, an electromagnetic wave source analyzing system, and an electromagnetic field analyzing and analyzing system.

[0002]

2. Description of the Related Art Electronic devices such as computers and electronic medical devices emit unnecessary electromagnetic waves when they operate, and often cause electromagnetic interference in wireless communication and the like. In many countries, on the other hand, unnecessary electromagnetic waves emitted from electronic devices are regulated to reduce the above-mentioned electromagnetic interference.

[0003] In Japan, a regulation value is set for the radiation level of unnecessary electromagnetic waves by the Voluntary Control Council for Interference by Information Processing Equipment (VCCI), and electronic equipment that does not satisfy this regulation cannot be sold substantially in Japan ( For example, from the above-mentioned VCCI issued by the Council, see No. 1). In order to suppress unnecessary electromagnetic wave radiation, a radiation source in the electronic device body is specified, and a radiation suppression measure is taken using a radio wave absorber or an electromagnetic shield.

Conventionally, to specify an electromagnetic radiation source on a main body,
A method of directly measuring the intensity of the electromagnetic wave source of the main body by an apparatus 31 in which electromagnetic radiation monitoring probes are arranged on a plane immediately adjacent to the electromagnetic wave source as shown in the block diagram of FIG.
An electromagnetic field distribution on a plane is measured by a two-dimensional electromagnetic field probe scanning device 32 for scanning an electric or magnetic field probe on a two-dimensional plane near the main body as shown in FIG. Method of creating an electromagnetic field strength map and specifying an electromagnetic wave source on the surface of the main body (for example, "Measures for shielding of 19-inch rack", IEICE, EM
C and its countermeasures workshop (material of the 2nd meeting), P61)
Etc. have been used.

[0005] Further, with respect to a method for measuring an unnecessary electromagnetic wave, a method for measuring an electric field intensity at a point 3 m or 10 m away from the radiation source main body on a conductor surface of about 50 to 500 m ² is defined (for example, the above-mentioned VCCI newsletter). , No1).

[0006]

However, when the above-described method for measuring an electromagnetic wave source is used, since the object to be measured is limited to a flat surface and the measurement is in the near field, the portion where the electromagnetic field intensity is strongly measured is not always radiated. There was a drawback that it was not linked to the source and was not sufficient from the viewpoint of measures to suppress unnecessary electromagnetic wave radiation.

In addition, the unnecessary electromagnetic wave measurement method requires a large site as a measurement place, and an area where broadcast waves and other electromagnetic noises are small in order to minimize the influence of electromagnetic waves other than the main body, or The measurement must be performed in an anechoic chamber, and the measurement cost is extremely high, which is not suitable as an experimental evaluation of radiation suppression measures.

SUMMARY OF THE INVENTION An object of the present invention is to solve such problems of the prior art, and to provide an electromagnetic wave source analysis system for obtaining a wave source distribution that contributes to measures to suppress unnecessary electromagnetic wave radiation, and to radiate the electromagnetic wave without being affected by the surrounding electromagnetic environment. An object of the present invention is to provide an electromagnetic field analysis system for obtaining an electromagnetic field, and a measuring device for measuring an electromagnetic field distribution which is indispensable in the configuration of the two systems.

[0009]

In order to achieve the above object, an electromagnetic field distribution measuring apparatus according to the present invention comprises an electromagnetic wave source main body.
For measuring electric and magnetic fields in response to electromagnetic radiation from
A field measurement probe, a mechanism for fixing the main body, and the probe.
A mechanism for scanning a lobe in a space around the main body,
Fixed to measure phase reference near the body
An electromagnetic field probe and an output signal of the electromagnetic field measuring probe
For measuring the amplitude of the electromagnetic field probe and the reference phase
It has a receiver that can measure the phase difference of the probe output signal.
And the electromagnetic field measurement probe detects the electromagnetic field at the measurement point.
The orientation to the main body around the sensitive part of the field measurement
It has a variable function.

[0010] An electromagnetic wave source analysis system according to the present invention.
Of the body's radiated electromagnetic field
Electromagnetic field on a curved or flat surface assuming the affected area
And outputs the electric and magnetic field strength signals and phase signals
Measuring means, and decoding the intensity and phase signals of the electric and magnetic fields.
Digital conversion means for digitally converting and outputting numerical data
And unnecessary electric charges on the surface and inside of the main body from the numerical data.
It has an inverse problem analysis function to find the distribution of magnetic radiation source.
Computer.

Further, the electromagnetic field analysis system according to the present invention is characterized in that the electromagnetic radiation from the main body is fixed to
Measure the phase of the electric and magnetic fields at
Measures strength and phase of enclosed electric and magnetic fields
And the strength of the closed surface electric field and magnetic field, and
At the fixed point near the body and the phase of the planar electric and magnetic fields
For outputting the phase difference between the electric field and the magnetic field phase
And the intensity signal of the electric field and the magnetic field of the closed surface and the position
Digital to convert the phase difference signal to digital and output numerical data
And a computer having an area integration function for obtaining an electromagnetic field at an arbitrary point of the electromagnetic wave emitted from the main body from the numerical data.

[0012]

[0013]

[0014]

The electromagnetic field on the curved surface surrounding the electromagnetic wave source body is measured, and the obtained electromagnetic field distribution is analyzed to obtain a wave source distribution which affects the suppression of unnecessary radio wave radiation. Further, an electromagnetic field distribution on a closed curved surface including the electromagnetic wave source main body is measured, and an electromagnetic field at an arbitrary point is obtained from the electromagnetic field distribution.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be specifically described below with reference to the drawings.

FIG. 1 is a perspective view of an electromagnetic field distribution measuring device 1 according to a first embodiment of the present invention and an electromagnetic wave radiation source main body 2. The electromagnetic field distribution measuring apparatus 1 includes two calibrated electromagnetic field measuring probes 3 which are arranged to face each other by 180 °.
And an electromagnetic field probe support 4 for supporting the electromagnetic field measurement probe 3, a pole 5 serving as a guide for moving the electromagnetic field measurement probe 3 up and down, It comprises a rotating table 6 for rotating by 180 °, an object-to-be-measured table 7 for mounting the electromagnetic wave radiation source main body 2, and a base 8.
The rotary table 6 rotates, but the DUT fixing table 7 can only adjust the height and does not rotate. This device 1
The components and materials constituting are made of non-metal such as plastic and wood as much as possible so as not to disturb the electromagnetic field distribution.

The electromagnetic field measuring probe 3 uses an electric field probe when measuring an electric field, and uses a magnetic field loop when measuring a magnetic field. Since the electromagnetic field probe support 4 slides perpendicular to the pole 5 and in the direction of the center of rotation, the electromagnetic field probe 3
Is variable.

A probe for measuring an electric field component or a magnetic field component in only one direction is used as the electromagnetic field measuring probe 3, and it is necessary to measure an electric field component or a magnetic field component in three orthogonal directions. The field probe support part 4 was provided with a mechanism that can change the direction of the electromagnetic field measurement probe in three orthogonal directions with the electromagnetic field sensing part of the electromagnetic field measurement probe 3 as the center.

The measuring apparatus 1 can rotate the electromagnetic field measuring probe 3 with a constant radius, move up and down, and independently move in the radial direction, so that the electromagnetic field distribution on the cylindrical closed curved surface surrounding the electromagnetic wave radiation source main body 2 can be measured. Can be measured. Since the electromagnetic field measurement probe 3 is calibrated, the absolute value of the electric field or the magnetic field at the probe position can be measured. To measure the phase, another electromagnetic field probe 9 fixed near the electronic device body is used as a phase reference. The electromagnetic field measurement probe 3 and a receiver (not shown) for receiving a signal of the measured electromagnetic field are connected through a high-frequency cable 10. Network analyzer and vector vol on receiver
Use a device such as a tomometer that can measure the amplitude and phase.

In this embodiment, the number of the electromagnetic field measuring probes 3 that can be moved is two in order to improve the efficiency of the measurement. However, one electromagnetic field measuring probe 3 may be rotated by 360 °.
Also, three or more may be used. If the electromagnetic field measuring probe 3 has a built-in electric-optical conversion function and uses an optical cable instead of the high-frequency cable 10, disturbance of the electromagnetic field can be prevented.

The method of fixing the electromagnetic wave radiation source main body 2 may be a structure in which the radiation source to be measured is hung instead of the table 7. The surface on which the electromagnetic field measurement probe 3 scans, that is, the measurement surface is not limited to a cylindrical surface, and may be a combination of other curved surfaces such as a sphere or an elliptical sphere, or a combination of flat surfaces.

FIG. 2 shows an electromagnetic wave source analysis system 1 according to the present invention.
FIG. This system 11 includes an electromagnetic field distribution measuring device 13 that measures the distribution of the intensity and phase of each of the electric field and magnetic field on a curved surface or a plane assumed to be in an area affected by the radiated electromagnetic field of the electromagnetic wave source main body 12, A digital converter 14 for converting the data of the intensity and phase of each of the electric and magnetic fields into digital numerical data; It comprises a computer 15 having an inverse problem calculation function for obtaining a distribution or a charge distribution, and a display device 16 for visually displaying the obtained wave source distribution.

For example, as shown in FIG. 3, the electromagnetic field at an arbitrary point P due to the electromagnetic radiation source 17 placed in the space is calculated by using the integral form of the Maxwell equation.

[0024]

(Equation 1)

J and ρ are the current density and charge density in the wave source body 31, ω is the angular frequency, μ is the magnetic permeability, ε is the permittivity, j = √ (−1), ∇ is the vector operator, and φ is the vector operator. ,
Green function (φ = exp (−jω / c) / r: r is the distance between the wave source and the point P, c is the speed of light) (for example, STRA
TTON, "Electro-Magnetic T"
heory ", McCGRAW-HILL BOOK
Ed., P. 466).

Therefore, E (p), H
If (p) is grasped, the current density distribution and the charge density distribution on the main body 31 as the wave source can be obtained by the inverse problem analysis method. The measurement range of E (p) and H (p) is
The area is set so as to cover most of the electromagnetic wave energy radiated from.

If the electromagnetic field distribution is measured on a closed curved surface surrounding the electromagnetic wave radiation source, all the electromagnetic energy emitted by the wave source 17 can be captured, so that a highly reliable electromagnetic wave source distribution can be obtained.

As the electromagnetic field distribution measuring device 13, the electromagnetic field distribution measuring device 1 shown in the first embodiment or another device capable of measuring the electromagnetic field distribution on a curved surface or a plane is used. By including the control of the electromagnetic field distribution measuring device 13 and the function of the digital converter 14 in the computer 15, the system can be fully automated.

FIG. 4 shows an analysis result of the current density 19 of the box-shaped metal electromagnetic radiation source body 18 obtained by the electromagnetic wave source analysis system according to the present invention. The charge on the radiation source surface is equivalently replaced by the current density. Since the distribution of the current density 19 is obtained from the measurement result of the radiated electromagnetic field, only components that contribute to radiation are shown. By suppressing the current density 19 using a radio wave absorbing material, an electromagnetic shield, or the like, unnecessary electromagnetic wave suppression measures can be efficiently performed.

FIG. 5 shows an electromagnetic field analysis system 21 according to the present invention.
FIG. The present system 21 includes an electromagnetic field distribution measuring device 23 that measures the distribution of the intensity and phase of all electric and magnetic fields on a closed curved surface surrounding the electromagnetic wave source main body 22, and the intensity and phase of each of the measured electric and magnetic fields. A digital converter 24 for converting data into digital numerical data, and a computer having an area integration function for calculating an electromagnetic field at an arbitrary point outside the closed surface from the converted digital numerical data of electric field and magnetic field intensity and phase And a display device 26 for visually displaying the obtained wave source distribution.

As shown in FIG. 6, two wave sources 2
7 and 28, a closed surface 29 surrounding the wave source 27.
Assuming that, the electric field E (p) and the magnetic field H (p) at an arbitrary point P outside the closed surface 29 are obtained by using the electric fields Es, Hs on the closed surface 29 by a modified integral form of Maxwell's equation.

[0032]

(Equation 2)

The area integral on the closed surface 29, ω is the angular frequency,
μ is magnetic permeability, ε is dielectric constant, j = ｊ (−1), ∇ is a vector operator, n is a unit normal vector taken inward of the closed surface 29, and φ is a Green function (φ = exp (− jω / c)
/ R: r is the distance between an arbitrary point on the closed curved surface 29 and the point P, and c is the speed of light).

When the positional relationship between the wave sources 27 and 28 and the closed curved surface 29 is as shown in FIG. 6, when performing the area integration on the closed curved surface 29 in the equations (3) and (4), The influence of the electromagnetic field radiated from the wave source 28 outside the closed curved surface 29 is removed, and the electric field E (p) and the magnetic field H (p) at the point P are only due to the radiation from the wave source 27.

Therefore, by measuring the distribution of the electromagnetic field on the closed curved surface 29 surrounding the wave source 27, the expression (3) and the expression (4) are obtained.
The calculation of the equation is performed to calculate the electric field E (p) and the magnetic field H at the point P.
(P) can be obtained. If there is a portion on the closed curved surface 29 where the effect of the radiated electromagnetic field from the external wave source 28 is extremely small, even if the electromagnetic field measurement of this portion is not performed,
That is, a highly reliable radiated electromagnetic field is required without measuring the electromagnetic field on a completely closed surface.

As the electromagnetic field distribution measuring device 23, the electromagnetic field distribution measuring device 1 shown in the first embodiment or another device capable of measuring the electromagnetic field distribution on a closed curved surface is used. The computer 25 includes the control of the electromagnetic field distribution measuring device 23 and the digital converter 2
This system can be fully automated by providing the functions of (4).

[0037]

As described above, according to the electromagnetic wave source analysis system of the present invention, it is possible to obtain the distribution of the wave sources affecting the suppression of the unnecessary electromagnetic wave radiation, and therefore, it is possible to efficiently take measures for suppressing the unnecessary electromagnetic wave. .

Further, according to the electromagnetic field analysis system of the present invention, the influence of the wave source outside the closed surface can be removed by measuring the electromagnetic field distribution of the closed surface surrounding the radiation source. This has the effect of being able to ascertain the electromagnetic field from the electromagnetic radiation source.

Further, the electromagnetic field distribution measuring device of the present invention has an effect that can be applied commonly to the electromagnetic field distribution measuring device constituting the above two systems.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an embodiment of an electromagnetic field distribution measuring device according to the present invention.

FIG. 2 is a block diagram showing a configuration of an electromagnetic wave source analysis system according to the present invention.

FIG. 3 is a diagram showing an analysis principle of the electromagnetic wave source analysis system of the present invention.

FIG. 4 is a diagram showing a current distribution on a wave source obtained by the electromagnetic wave source analysis system of the present invention.

FIG. 5 is a block diagram showing a configuration of an electromagnetic field analysis system according to the present invention.

FIG. 6 is a diagram showing the analysis principle of the electromagnetic field analysis system according to the present invention.

FIG. 7 is a block diagram of a conventional electromagnetic field distribution measuring device.

FIG. 8 is a perspective view of a conventional two-dimensional electromagnetic field distribution measuring device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Electromagnetic field distribution measuring device 2 Electromagnetic wave radiation source main body 3 Electromagnetic field measuring probe 4 Electromagnetic field probe support part 5 Pole 6 Rotary table 7 Table for fixing object to be measured 8 Base 9 Fixed electromagnetic field probe for phase reference measurement 10 High frequency cable 11 Electromagnetic wave source analysis system 12 Electromagnetic wave source body 13 Electromagnetic field distribution measuring device 14 Analog-digital converter 15 Computer having inverse problem calculation function 16 Visualization display device 17 Wave source 18 Metal box-shaped electromagnetic radiation source 19 Current density 21 Electromagnetic field Analysis system 22 Electromagnetic wave source main body 23 Electromagnetic field distribution measuring device on closed surface 24 Analog-digital converter 25 Computer having area integral calculation function 26 Visualization display device 27 Wave source inside closed surface 28 Wave source outside closed surface 29 Closed surface

Continuation of the front page (56) References JP-A-1-312472 (JP, A) JP-A-4-329376 (JP, A) JP-A-5-26928 (JP, A) JP-A-2-81479 (JP) , U)

Claims (3)

(57) [Claims] An electromagnetic field measuring probe for measuring an electric field and a magnetic field with respect to electromagnetic radiation from an electromagnetic wave source main body; a mechanism for fixing the main body; a mechanism for scanning the probe in a space around the main body; An electromagnetic field probe fixed for measuring a phase reference near the main body, an amplitude of an output signal of the electromagnetic field measuring probe, and a phase difference between an output signal of the electromagnetic field measuring probe and an output signal of the reference phase measuring probe are measured. And a receiver capable of changing the direction of the electromagnetic field measurement probe at a measurement point with respect to the main body around a portion where the electromagnetic field measurement is sensed at the measurement point. measuring device. 2. An electromagnetic field from a main body is measured on a curved surface or a plane assumed to be in an area where the radiated electromagnetic field of the main body is affected, and an intensity signal and a phase signal of the electric and magnetic fields are output. Measuring means, digital converting means for converting the electric field and magnetic field intensity signals and phase signals into digital data and outputting numerical data, and an inverse method for obtaining the distribution of unnecessary electromagnetic wave radiation wave sources on the surface and inside of the main body from the numerical data. An electromagnetic wave source analysis system comprising a computer having a problem analysis function. 3. In the vicinity of the main body against electromagnetic radiation from the main body.
Measuring the phase of the electric and magnetic fields at the fixed point of
The strength and phase of electric and magnetic fields in the form of a closed surface surrounding the body
Are measured, and the intensity of the electric field and magnetic field of the closed
The phase of the electric field and the magnetic field of the closed curved surface and the
Outputs the phase difference between the electric and magnetic fields at a fixed point
Means, and the intensity signal of the electric field and magnetic field of the closed curved surface and
Digitally convert the phase difference signal and output numerical data
An electromagnetic field analysis system comprising: a digital conversion means; and a computer having an area integration function for obtaining an electromagnetic field at an arbitrary point of an electromagnetic wave emitted from the main body from the numerical data.