JPH08220164A - Estimating method of effect of countermeasure against electromagnetic jamming wave - Google Patents

Abstract

PURPOSE: To improve reproducibility and also to estimate accurately the effect of a countermeasure against a jamming wave which changes sharply according to a place, by using a movable type antenna and others which are provided at a prescribed position outside a building wherein electronic equipment is installed. CONSTITUTION: Electronic equipment 2 for which a countermeasure against an electromagnetic jamming wave is taken is installed inside a building 1. Outside the building 1, there is an area 3 for measuring the effect of the countermeasure against the electromagnetic jamming wave and a movable type measuring antenna 4, a jamming wave measuring device 5 and a computer 6 for processing measured data are provided in this area 3. The electromagnetic jamming wave radiated from the electronic equipment 2 is measured before and after the countermeasure against the electromagnetic jamming wave is taken for the electronic equipment 2. Concretely, the strength of the electromagnetic jamming wave radiated from the electronic equipment 2 before the countermeasure is taken is measured by the antenna 4 on a concentric circle from the center of the building 1 and on a line of a length determined by a frequency and the dimensions of the building 1. Next, the jamming wave radiated after the countermeasure is taken is measured in the same way. By using measured values thus obtained, the effect of the countermeasure against the electromagnetic jamming is computed and estimated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electromagnetic interference wave countermeasure effect evaluation method for measuring and evaluating, outside a building, the effect of an electromagnetic wave interference countermeasure for reducing a radiation interference wave of an electronic device which is carried out at a place where an electronic device is installed. It is about.

[0002]

2. Description of the Related Art In recent years, radiated interference waves of electronic devices have increased due to digitalization, high speed and high density mounting of electronic devices, but the immunity to electromagnetic interference waves has tended to weaken. The number of environments where the resulting failures are likely to occur is increasing. For this reason, it is obliged for electronic devices to set the radiated emission level of the device to a standard value or lower defined by VCCI (Voluntary Control Council for Interference for Information Processing Devices).

Under these circumstances, the following methods are mainly used as countermeasures against interference waves. (1) Board-level interference wave countermeasures in which a filter or ferrite core is placed in the electronic circuit of the equipment to take countermeasures. (2) Measures such as adding conductive paint or a shield gasket to the device case to improve the case's shielding effect. (3) Countermeasures against interference at the building level by installing shield walls around the equipment.

Countermeasures against these interference waves are mainly carried out at the laboratory level such as an anechoic chamber or a shielded room, and the measurement method and evaluation method of the interference waves are FCC, CISPR and VCC.
It is specified in detail in I etc. However, in reality, there are many cases where these interference countermeasures are taken at the installation location of the device. It is not clear how the disturbing waves are distributed in the installation site or outside the building, and the method of measuring and evaluating the disturbing waves is not currently defined. The effectiveness of the measures against interference is highly reproducible and depends largely on the person involved.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned circumstances, and the reproducibility is measured by measuring and evaluating the effect of electromagnetic interference measures in the vicinity of the building where the device is installed. At the same time, it is an object of the present invention to provide an electromagnetic interference wave countermeasure effect evaluation method that more accurately evaluates an interference wave countermeasure effect that varies greatly depending on the location.

[0006]

To achieve the above object, the present invention provides an electromagnetic wave applied to an electronic device by using a ferrite core, a shield housing, a shield wall, or the like in a building where the electronic device is installed. In an electromagnetic interference countermeasure effectiveness evaluation method for measuring and evaluating the effect of the interference countermeasure outside the building, a mobile measuring antenna installed at a predetermined position and height outside the building, and an electromagnetic wave received by the measuring antenna It is composed of detection means for detecting the level, a memory for storing the measurement result, a CPU for performing a predetermined processing based on the measurement result, and an output device for outputting the processing result. , Before and after measures against electromagnetic interference, starting from a predetermined place outside the building, measuring frequency on a concentric circle from the center of the building and the place where the electronic device is installed Measured by the mobile measuring antenna on a line of a length obtained from the size, the measurement result is stored in the memory, and the line before and after the electromagnetic interference wave countermeasure stored in the memory is measured. Using the maximum values in the height direction of the polarization components in the three directions of the electromagnetic wave at the respective measurement positions of, the electromagnetic interference wave countermeasure effect for the respective polarization components in the three directions on the line and the electromagnetic wave combining the three-direction components An interfering wave countermeasure effect is obtained, and the result is output from the output device.

[0007]

According to the present invention by the above means, first of all, in a concentric circle from the center of the building, starting from a predetermined location outside the building, which is the installation location, of a length determined from the frequency and the size of the building. The strength of the electromagnetic interference wave radiated from the electronic device before taking measures against the interference wave on the line is measured by a mobile measuring antenna. Next, the electromagnetic interference wave radiated from the electronic device after taking measures against the electromagnetic interference wave is measured on the same concentric circle. The most important feature is that the electromagnetic interference wave countermeasure effect at each position on the concentric circle is calculated using these measured values, and the electromagnetic interference wave countermeasure effect on the line is evaluated.

In the prior art, since the position for measuring the interference wave countermeasure effect and its evaluation method have not been clarified, the interference wave countermeasure effect largely depends on the measurer and it is difficult to perform reproducible evaluation. The invention evaluates the anti-jamming effect in a range of a length determined from the frequency and the size of the building on a concentric circle drawn from the center of the building, starting from a place with a predetermined distance outside the building, which is the installation location. As a result, it is possible to more accurately evaluate the interfering wave countermeasure effect that is reproducible and that varies greatly depending on the location.

[0009]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a diagram showing a measurement system as seen from the upper side outside a building in one embodiment of the present invention. In the figure, an electronic device 2 that provides countermeasures against electromagnetic interference is installed in a building 1. Outside the building 1, there is an area 3 for measuring the effect of measures against electromagnetic interference, and in this area 3 a mobile measuring antenna 4, an interference measuring device 5 such as a test receiver 5 and a computer 6 for processing measurement data are installed. To be done. Although not shown, the computer 6 includes a CPU for performing calculations and data processing described later, a memory for storing the result, a display for displaying the result, and the like.

Next, a method of measuring the electromagnetic interference wave radiated from the electronic device 2 before and after the electromagnetic interference wave countermeasure is applied to the electronic device 2 will be described with reference to FIG. In FIG. 2, a concentric circle 8 and a radial line 9 drawn from the center point 7 of the building 1 are shown on the region 3 where the electromagnetic interference countermeasure effect is measured. Here, if the frequency to be measured is f (MHz), the wavelength λ
Is 300 / f (m). At this time, the angle 11 of the radial line drawn from the center of the building when the horizontal length 10 on the wall surface of the building 1 is one wavelength is θ °. As will be described later, the electromagnetic interference wave countermeasure effect is distributed radially from the center point 7 of the building at an interval of an angle 11 obtained from the frequency and the size of the building, and even if the distance from the building 1 is further increased, a countermeasure on a radial line is obtained. The effect hardly changes. Therefore, for example, the electromagnetic interference wave is measured on the measurement line 12 having the same angle 11 as the radial line on the concentric circle 8 at an arbitrary distance from the building 1. However, at this time, the movable measuring antenna 4 is fixed at a horizontal position 13 on the measurement line 12 as shown in FIG. 3, and is moved from the lowest position to the highest position for measurement. . The fixed position 13 in the horizontal direction is set on the measurement line 12 at least at a quarter wavelength interval or less. The direction of the mobile measuring antenna 4 is, as shown in FIG.
The respective polarization components are measured in the three directions of 5 and 16.

These measured values are stored in the computer 6. On the computer 6, the maximum electric field strength in the height direction of each polarization component at each measurement position 13 is obtained. Here, obtaining the maximum electric field strength in the height direction of each polarization component is the same principle as the electromagnetic interference wave evaluation method in an anechoic chamber specified by CISPR, FCC, VCCI, etc.
It is also for maintaining reproducibility of measurement results. Here, the value obtained at a certain measurement position P, respectively E _x ⁱ before being subjected to electromagnetic interference ^{_{countermeasure, E y i, E z i}} , after applying the electromagnetic interference countermeasure E _x ^t, E _y ^t , E _z ^t . At this time, the electromagnetic interference wave countermeasure effect at point P is the value for each polarization component.

[0012]

[Equation 1] Can be evaluated with. Further, since the electromagnetic interference wave countermeasure effect has the maximum value and the minimum value in the direction on the concentric measurement line 12, the electromagnetic interference wave countermeasure effect on the measurement line 12 is evaluated.

The results of actual application of the above-mentioned electromagnetic interference wave countermeasure effect evaluation method are shown below. FIG. 5 shows the structure of the building 17. As a countermeasure against electromagnetic interference, a ferrite core was inserted into the communication line portion of the communication device 18. FIG. 6 shows a view around the building 17. The 40 m line 19 is a line in which the electromagnetic interference wave actually radiated from the communication device 18 is measured. In addition to the measured values, the region 20 in which the electromagnetic field distribution around the building 17 is estimated using the method of moments is also shown here. In the estimation using the method of moments, the building 17 was approximated by a wire grid model simulating a steel frame structure, and the Galerkin method using a piecewise sine wave as an expansion function was used.

FIG. 7 shows the effect of countermeasures against electromagnetic interference waves in the line 19 when the frequency is 90 MHz. The electromagnetic interference wave countermeasure effect was calculated from equation (4). The figure shows the values when the height of the mobile measuring antenna 4 is fixed to 2 m and 4 m,
The values calculated using the maximum value in the height direction between 1 m and 4 m are also shown. As shown in the figure, when the height of the movable measuring antenna 4 is fixed, the value greatly varies in the height direction due to the height pattern, but if the maximum value in the height direction is evaluated, neither excessive nor underestimation will occur. I understand. In addition, the measured value and the calculated value have a deviation of about 20 dB depending on the location, but when evaluated using the maximum value in the height direction, the maximum deviation is within about 5 dB. It can be seen that the effect can be estimated.

FIG. 8 shows the result of calculation of the distribution of the electromagnetic wave interference countermeasure effect in the peripheral area 20 of the building 17 using the method of moments.
Shown in The figure (a) is the case of a frequency of 90 MHz,
The figure (b) is in the case of a frequency of 170 MHz. In addition, the electromagnetic interference wave countermeasure effect was calculated from Equation (4) using the maximum values in the height direction in both (a) and (b). In both figures, concentric circles at intervals of 10 m from the center of the building 17 and radial lines at intervals of 10 ° are also shown. As described above, it can be seen that the electromagnetic interference wave countermeasure effect is distributed along the radial line drawn from the center of the building 17 for both frequencies. It is also understood that when the building 17 is separated from the building 17 along the radial line, it changes by several dB in a place where the electromagnetic interference wave countermeasure effect is low, but hardly changes in a place where the electromagnetic interference wave countermeasure effect is high. Therefore, it is almost unnecessary to consider how far away from the building 17 the electromagnetic interference wave countermeasure effect should be, and it is sufficient to measure at any place where measurement is possible.

FIG. 9 shows a radial line drawn from the center 21 of the building 17. In the figure, the length of l ₁ is 3.3 m, which corresponds to one wavelength at 90 MHz. The length of l ₂ is 1.8 m, which corresponds to one wavelength at 170 MHz. The angle of the radial line corresponding to l ₁ is θ ₁ = 32 °, and the angle corresponding to l ₂ is θ ₂
= 16 °. As can be seen from FIG. 8, frequency 90M
In the case of Hz, the electromagnetic interference wave distribution is distributed on the wall surface of the building 17 at intervals of about 30 °, which is almost the same as the angle of about 1 wavelength, and in the case of a frequency of 170 MHz, the electromagnetic interference wave distribution is also about the same on the wall surface of the building 17. It is distributed at intervals of about 18 °, which is one wavelength. When the whole building is viewed from a sufficient distance from the wavelength, it can be considered that the building is a small radiation source and the disturbance wave is emitted from the center of the building. At this time, the distribution of directional interfering waves of the radiation source is determined. It is the building beams that most contribute to the horizontal emission of the interfering waves. The induced current is distributed, and the disturbance wave is re-radiated from this induced current. Considering the induced current on the beam of a building as a radiation source arranged at intervals of one wavelength, this 1
It is considered that the distribution can be understood to some extent by observing the extension of the radiation source of the wavelength length.

In order to confirm whether the above is true for buildings of other shapes, the electromagnetic interference countermeasure effect was calculated for the small building 22 shown in FIG. However, the electromagnetic interference wave countermeasure effect in this case is that the radiation source 23 is set to x = 1.25.
The shield effect of the shield wall 24 when installed at the positions of m, y = 4.75 m and z = 1.5 m was used. FIG. 11 shows a region 25 where the effect of countermeasures against electromagnetic interference is calculated. 12
(A) shows the electromagnetic interference wave countermeasure effect distribution when the frequency is 90 MHz, and (b) shows the electromagnetic interference wave countermeasure effect distribution when the frequency is 170 MHz. Also, in both figures, concentric circles with 10 m intervals drawn from the center of the building 22 and 10
° radial lines were shown. From the figure, the building 1
As in the case of No. 7, the electromagnetic interference wave countermeasure effect is distributed radially, and it can be seen that the electromagnetic interference wave countermeasure effect on the radial line hardly changes even if it is separated from the building 22. Also,
It can be seen that the distribution interval of the electromagnetic interference countermeasure effect is about 70 ° at 90 MHz and about 40 ° at 170 MHz.

Similar to FIG. 9, FIG. 13 shows a radial line drawn from the building 22 and the center 26 of the building. In the figure, l
The length of ₁ is 3.3m corresponding to one wavelength when the frequency 90 MHz, the length of l ₂ is 1.8m corresponding to one wavelength when the frequency 170 MHz. radial angle theta ₁ of the line corresponding to the l ₁ is 68 °, the angle theta ₂ which corresponds to l ₂ is 38 °, they FIG. 12 (a), the
It is in good agreement with the distribution angle of the electromagnetic interference wave countermeasure effect shown in (b). Therefore, in any building, the electromagnetic interference countermeasure effect is distributed at the angular intervals of the radial lines when the horizontal line spacing of the radial lines drawn from the center of the building is one wavelength. It can be said that

After all, as shown in FIG. 14, when measuring the electromagnetic interference countermeasure effect outside the building 27, the building 2
The angle at which the distance between the radial lines drawn from the center 28 of the building 27 is one wavelength of the measurement frequency on the wall surface in the area to be measured at a position distant from the center 28 of the body 7 by an arbitrary distance r (m) is θ. Then, it is understood that the electromagnetic interference wave should be measured on a line on a concentric circle having a length of about d = 2 rtan θ (m), and the distribution of the electromagnetic interference wave countermeasure effect on this line should be evaluated. Since the maximum value and the minimum value of the electromagnetic interference wave countermeasure effect in that direction are included on this line, the performance of the electromagnetic interference wave countermeasure can be grasped.

[0020] As described above, first, at a predetermined location outside the building, which is the installation location, on a concentric circle from the center of the building, a line having a length determined by the frequency and the size of the building is disturbed. The strength of the electromagnetic interference wave radiated from the electronic device before the countermeasure against the wave is measured by the mobile measuring antenna.
Next, the electromagnetic interference wave radiated from the electronic device after taking measures against the electromagnetic interference wave is measured on the same concentric circle. Then, the electromagnetic interference wave countermeasure effect at each position on the concentric circle is calculated using these measured values, and the electromagnetic interference wave countermeasure effect on the line is evaluated.

In the prior art, since the position for measuring the interference wave countermeasure effect and its evaluation method have not been clarified, the interference wave countermeasure effect greatly depends on the measurer and it is difficult to perform reproducible evaluation. The invention evaluates the anti-jamming effect in a range of a length determined from the frequency and the size of the building on a concentric circle drawn from the center of the building, starting from a place with a predetermined distance outside the building, which is the installation location. As a result, it is possible to more accurately evaluate the interfering wave countermeasure effect that is reproducible and that varies greatly depending on the location.

[0022]

As described above, according to the electromagnetic interference wave countermeasure effect evaluation method of the present invention, the interval of distribution of the electromagnetic interference wave countermeasure effect is obtained from the frequency and the size of the building, and the electromagnetic interference within this interval is obtained. If the wave countermeasure effect is evaluated, it is possible to more accurately evaluate the disturbing wave countermeasure effect, which is reproducible and varies greatly depending on the location.

Therefore, by evaluating the effects of various measures against electromagnetic interference using the present invention, it is possible to take measures against electromagnetic interference taking the distribution of electromagnetic interference into consideration, and the effect of measures against the measurer. Independent anti-jamming measures can be implemented.

[Brief description of drawings]

FIG. 1 is a top view of a building and a measurement system for preventing electromagnetic interference in the outside thereof according to an embodiment of the present invention.

FIG. 2 shows a building and a concentric circle and a radial line drawn from the center of the building in one embodiment of the present invention.

FIG. 3 shows a schematic diagram of measurement positions on a concentric circle drawn from the center of a building in one embodiment of the present invention.

FIG. 4 illustrates an installation direction of a mobile measurement antenna according to an embodiment of the present invention.

FIG. 5 illustrates a building shape and a communication device according to an embodiment of the present invention.

FIG. 6 shows a measurement line and an estimated area of a building and an electromagnetic interference countermeasure effect in one embodiment of the present invention.

FIG. 7 shows a measurement result and an estimation result of an electromagnetic interference wave countermeasure effect in one embodiment of the present invention.

FIG. 8 shows the estimation result of the electromagnetic interference wave countermeasure effect distribution in one embodiment of the present invention.

FIG. 9 illustrates a building and a radial line drawn from the center of the building in one embodiment of the present invention.

FIG. 10 shows a shape of a building, an electromagnetic interference wave source, and a shield wall in one embodiment of the present invention.

FIG. 11 shows a building and an electromagnetic interference wave countermeasure effect estimation region in one embodiment of the present invention.

FIG. 12 shows the estimation result of the electromagnetic interference wave countermeasure effect distribution in one example of the present invention.

FIG. 13 shows a building and a radial line drawn from the center of the building in one embodiment of the present invention.

FIG. 14 is a view from the center of a building in one embodiment of the present invention;
(M) shows an electromagnetic interference wave measurement line at a distant position.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Building 2 ... Electronic device 3 ... Measuring area 4 ... Mobile measuring antenna 5 ... Interference measuring device 6 ... Computer 7 ... Center point of building 8 ... Concentric circle from center of building 9 ... Radial drawn from center of building Line 10 ... Length of one wavelength in the horizontal direction on the wall of the building 11 ... Angle of radial line corresponding to the length of one wavelength in the horizontal direction on the wall of the building 12 ... Electromagnetic interference at a position away from the building by an arbitrary distance Measurement line for wave countermeasure effect 13 ... Installation position of mobile measurement antenna 14 ... Direction of polarization plane of mobile measurement antenna 15 ... Direction of polarization plane of mobile measurement antenna 16 ... Polarization plane of mobile measurement antenna Direction 17 ... Building 18 ... Communication device 19 ... Electromagnetic interference measure effect measurement line 20 ... Electromagnetic interference measure effect estimation area 21 ... Building center 22 ... Building 23 ... Electromagnetic interference source 24 ... Rudo wall 25 ... of the estimated area 26 ... Building electromagnetic interference suppressing effect around 27 ... building 28 ... center of the building

Claims (1)

[Claims] 1. An electromagnetic interference for measuring and evaluating the effect of an electromagnetic interference wave countermeasure applied to an electronic device by using a ferrite core, a shield housing, a shield wall, or the like inside the building where the electronic device is installed, outside the building. In the wave countermeasure effect evaluation method, a mobile measurement antenna installed at a predetermined position and height outside a building, a detection unit that detects the level of an electromagnetic wave received by the measurement antenna, and a memory that stores the measurement result. ,
It is composed of a CPU that performs predetermined processing based on the measurement result and an output device that outputs the processing result. The strength of the electromagnetic wave radiated from the electronic device is measured outside the building before and after the electromagnetic interference wave countermeasures. Starting from a predetermined location, measured with the mobile measurement antenna on a line of a length obtained from the size of the building where the frequency is measured and the installation location of the electronic device on a concentric circle from the center of the building,
The measurement results are stored in the memory, and the maximum values in the height direction of the polarization components in the three directions of the electromagnetic waves at the respective measurement positions on the line before and after the electromagnetic interference measures stored in the memory are stored. Is used to obtain the electromagnetic interference wave countermeasure effect for each polarization component in the three directions on the line and the electromagnetic interference wave countermeasure effect obtained by combining the three-direction components, and the result is output from the output device. Electromagnetic interference countermeasure effectiveness evaluation method.