JP2000180489A - Simple electromagnetic wave-measuring box - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce in size and to substantially accurately measure a resistance and shielding characteristics by reflecting and scattering an electromagnetic wave reflected in a box, reducing its resonance, and averaging a limiting intensity of the wave operate for a machine to be measured. SOLUTION: An electromagnetic equipment 7 to be measured is set on a measuring base 13. When electric motors 9a, 11a of electromagnetic agitating members 9, 11 are driven and an electromagnetic wave is transmitted from a transmitting antenna 17 while rotating metal discs 9c, 11c, an electric field intensity in the simple electromagnetic wave-measuring box becomes irregular. Meanwhile, when the intensity in the box 1 is averaged to a certain timing degree, the wave of an electromagnetic field intensity averaged to the certain degree can be operated for the equipment 7 on the base 13. In this state, resistance limiting values of a frequency and an output of the wave output from the antenna 17 are altered, and frequency and output of the wave in the case of malfunction of the equipment 7 are measured.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tolerance test for measuring the frequency and the output limit value when various electronic devices malfunction due to an external electromagnetic wave, and for measuring a shield characteristic of an electromagnetic wave shield such as a shield case. The present invention relates to a simple electromagnetic wave measurement box used in such a case.

[0002]

Generally, IEC-1000-4-3 is specified as an international standard as a standard for a measurement room such as an anechoic chamber used for performing a resistance test of electronic equipment. This standard IEC-1000-4-3 is 1.5 meters at a position 3 m in front of the antenna installed in the measurement room.
Assuming an m-square virtual screen at a height of 0.8 m, assuming 16 points at 0.5 m intervals on the virtual screen, measure the electric field strength of electromagnetic waves passing through each point. Then, based on an arbitrary point at each point,
The electric field intensity ratio between the point and another point is 0 to 6d
Points within B are 75% of the total points 12
If the number of points is equal to or more than the point, it is determined that the measurement room is suitable for performing a malfunction confirmation test of the electronic device.

That is, in a measurement room, an electromagnetic wave output from an antenna is radiated in a direction other than the directing direction, or reflected by a wall surface or a ceiling surface after passing through a virtual screen, and passes through each point. Although they interfere with each other and resonate, and the electric field strength at each point is greatly different, in such a measurement environment, it is impossible to accurately measure the resistance and the shield characteristics of the electronic device to be measured. For this reason, a measurement room used for these applications is required to have the electric field strength of the electromagnetic wave in the measurement room averaged to some extent over time.

However, the above-mentioned IEC-1000
The measurement room itself, which meets the requirements of -4-3, needs to place the electronic equipment to be measured at a position 3 m in front of the transmitting antenna and 0.8 m from the floor, which inevitably increases the size. Also, it is necessary to increase the output of the electromagnetic wave itself used for measurement, and the equipment itself is extremely expensive. As a result, the measurement cost was extremely high.

Conventionally, when measuring the electromagnetic wave shielding characteristics of various electronic devices such as a shield case, for example, a flat electronic device to be measured is disposed between a transmitting antenna and a receiving antenna, and a receiving device for a transmitting output is received. Although the electromagnetic wave transmission attenuation of the electronic device under test is measured based on the strength, the conventional measurement method limits the measurement target to a flat plate, and as a result, the shield of the entire electronic device under test is shielded. Properties could not be measured.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned conventional drawbacks. The object of the present invention is to reduce the size of the device itself and to measure the resistance and shielding characteristics of various electronic devices properly. Suitable for the pre-measurement of this test, and can average the electric field strength of the electromagnetic wave in the interior over time to measure the resistance and shielding characteristics of various equipment under test almost accurately and in a state close to a practical use. An object of the present invention is to provide a simple electromagnetic wave measurement box.

Another object of the present invention is to provide a simple electromagnetic wave measurement box which can reduce the measurement cost.

[0008]

For this reason, the present invention provides a metal box having a small-capacity space corresponding to the frequency band of an electromagnetic wave used for measurement, and a metal box arranged at the center of the space of the box. Electronic equipment to be measured set on the measuring table,
A transmitting unit that is provided near the electronic device to be measured and outputs an electromagnetic wave having a predetermined frequency band and an output; and is disposed in a box, and reflects and scatters the electromagnetic wave output from the transmitting unit and reflected in the box. An electromagnetic wave agitating means for reducing the electromagnetic wave resonance phenomenon, and time-averaging the electric field strength of the electromagnetic wave transmitted from the transmitting means and acting on the electronic device to be measured, to measure a resistance limit value of the electronic device to be measured. It is made possible.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic perspective view of a simplified electromagnetic wave measurement box.

The box 3 of the simplified electromagnetic wave measurement box 1 is a metal plate such as an iron plate or an aluminum plate having an electromagnetic wave reflection characteristic, and has a small internal capacity corresponding to an electromagnetic wave frequency band used for measurement. In the present embodiment, a rectangular shape having a width of 0.7 m, a depth of 0.6 m, and a height of 0.8 m is used in order to use an electromagnetic wave having a frequency band of 400 to 2500 MHz. As described above, the internal capacity of the box 3 is appropriately selected based on the frequency band of the electromagnetic wave used for the measurement, that is, the wavelength, and can be further reduced in the case of a high frequency band.

An opening (not shown) provided on the front plate of the box 3 is opened and closed by a door 5, and an electronic device 7 to be measured described later is carried into and out of the box 3 through the opening. The door 5 is provided with a transmission window 5a containing a metal mesh, and the electronic device 7 to be measured in the box 3 can be visually recognized through the transmission window 5a.

At least two electromagnetic wave stirring members 9 and 11 are mounted in the box 3 so that their axes are orthogonal to each other, for example, in the X-axis direction and the Y-axis direction. Each of the electromagnetic wave stirring members 9 and 11 is attached to the outside of the box 3 and has a plurality of cutouts 9 b and 11 b formed at equal intervals in a circumferential direction on a rotating shaft of the electric motors 9 a and 11 a inserted into the box 3. It has a structure to which the discs 9c and 11c are attached.

The metal disk 9c-1 in the circumferential direction
The width of the blades 9d and 11d and the cutouts 9b and 11b in 1c is set according to the frequency band of the electromagnetic wave used for measurement.
The widths of the notches 9b and 11b may be set narrow. or,
Each of the metal disks 9c and 11c is rotated at a different rotation speed. The rotation speed of the metal disks 9c and 11c is also set according to the frequency band of the electromagnetic wave used for measurement.

A measuring table 13 is provided inside the box 3, and the electronic device 7 to be measured set on the measuring table 13 is positioned at the center of the space in the box 3. When the resistance test of the electronic device 7 to be measured is performed, the transmitting antenna 17 connected to the transmitting device 15 provided outside is used.
Is arranged. As described above, the transmitting device 15
An electromagnetic wave of 0 to 2500 MHz and an output of about 2 to 5 W is output from the transmitting antenna 17. When the electromagnetic wave shielding characteristics of the electronic device 7 to be measured are measured, the transmitting antenna 17 is arranged inside the electronic device 7 to be measured, and the receiving device 19 provided outside in the box 3 is provided.
Are provided at a predetermined measurement interval from the electronic device 7 to be measured.

The transmitting antenna 17 and the receiving antenna 2
In a first installation mode, the transmission antenna 17 may be installed inside the box 3 and the reception antenna 21 may be installed inside the electronic device 7 to be measured. When a resistance test is performed, a connector (not shown) for taking out a monitor signal from the electronic device 7 to be measured is provided inside the box 3, and the resistance state of the electronic device 7 to be measured is provided. May be monitored externally.

An electromagnetic wave absorber 23 is appropriately attached to the inner surface of the box 3. The electromagnetic wave absorber 23 absorbs the electromagnetic wave whose reflection is disturbed by the unevenness of the measuring table 13 and the electronic device 7 to be measured arranged in the box 3, and reduces the Q value in the box 3 together with the electromagnetic wave stirring members 9 and 11 described above. By lowering it, the electric field intensity in the box 3 is made uniform to some extent. The electromagnetic wave absorber 23 is desirably a thin type because of the small capacity of the box 3 itself, for example, a thickness of 20 to 50 mm.
Although a structure in which two dielectric ferrite plates having a thickness of 2 to 3 mm and a thickness of 3 to 5 mm are laminated and laminated with each other is suitable, the present invention is not limited thereto.

Next, a measuring method using the above-described simple electromagnetic wave measuring box will be described. FIG. 2 is a chart showing an example of the electric field intensity at the center of the simplified electromagnetic wave measurement box when the electromagnetic wave stirring member is not operated. FIG. 3 is a chart showing an example of the electric field intensity at the center of the simplified electromagnetic wave measurement box during operation of the electromagnetic wave stirring member. FIG. 4 is a chart showing the relationship between the input power obtained in the simplified electromagnetic wave measurement box and the expected electric field strength (average).

For example, when measuring the resistance limit value of the electronic device 7 to be measured, the electronic device 7 to be measured for the resistance test is set on the measuring table 13 through the opened opening. At this time, the monitor signal output cable of the electronic device 7 to be measured is connected to the connector as required, so that monitoring can be performed outside the simplified electromagnetic wave measurement box 1.

Next, while driving the electric motors 9a and 11a of the electromagnetic wave stirring members 9 and 11 to rotate the metal disks 9c and 11c at different rotational speeds, the electromagnetic waves having the frequencies of 400 to 2500 MHz are selected from the transmitting antenna 17. To send. At this time, when an electromagnetic wave is output from the transmitting antenna 17 in a non-rotating state of the metal disks 9c and 11c, the electromagnetic waves are reflected and interfere with each other by the wall surface of the simplified electromagnetic wave measuring box 1 as shown in FIG. However, as a result of the Q value of the simplified electromagnetic wave measurement box 1 being increased, the electric field intensity in the simplified electromagnetic wave measurement box 1 becomes non-uniform.

On the other hand, when electromagnetic waves are output from the transmitting antenna 17 in a state where the metal disks 9c and 11c are rotated at different rotational speeds, the rotating metal disks 9c and 11c are used as shown in FIG. Reduce turbulence of electromagnetic waves to reduce Q
As a result, the electric field intensity in the simplified electromagnetic wave measurement box 1 is averaged to some extent over time. As a result, it is possible to apply an electromagnetic wave having an electric field intensity having a certain level of uniformity to the electronic device 7 to be measured set on the measuring table 13.

In the above state, the frequency and output of the electromagnetic wave output from the transmission antenna 17 are selectively varied, and the limit value of the electromagnetic wave frequency and output when the electronic device 7 to be measured malfunctions is measured.

The resistance limit of the electronic equipment 7 to be measured is determined by the door 5
The malfunction of the electronic device 7 to be measured may be visually confirmed through the transmission window 5a provided in the device, or may be confirmed by a monitor signal from the electronic device 7 to be measured.

On the other hand, when measuring the shield characteristics of a shield case or the like, the transmitting antenna 17 is inserted into the electronic device 7 to be measured set on the measuring table 13 and set. The receiving antenna 21 is set in the box 3 having the measurement interval of.

In this state, if the metal discs 9c and 11c of the electromagnetic wave stirring members 9 and 11 are rotated at different rotational speeds and the transmission antenna 17 selectively outputs a frequency of 400 to 2500 MHz, as described above. The resonance of the electromagnetic wave in the simplified electromagnetic wave measurement box 1 is reduced to reduce the Q value so that the electric field intensity of the electromagnetic wave transmitted through the electronic device 7 to be measured is substantially averaged over time.

Then, the intensity of the electromagnetic wave received via the receiving antenna 21 is measured while selectively varying the frequency and output of the electromagnetic wave output from the transmitting antenna 17, and the reception intensity with respect to the frequency and power of the output electromagnetic wave is measured. From the relationship, the shield characteristic of the electronic device 7 to be measured is measured. In this measurement, even if the electronic device 7 to be measured has an arbitrary three-dimensional shape, its shield characteristics can be measured.

In the present embodiment, prior to the main measurement of the resistance limit value and the shield characteristic of the electronic device 7 to be measured, the resistance and the shield characteristic of the electronic device 7 to be measured are measured in advance, and the measurement is performed so as to conform to the main measurement. The resistance and shield characteristics of the electronic device 7 can be easily adjusted in advance, and the main measurement can be performed at low cost.

In the small-capacity box 3, the electromagnetic waves are reflected and resonated inside, and the Q value is increased. As a result, the electric field strength of the electromagnetic waves acting on the electronic device 7 to be measured is temporally reduced. Although it cannot be averaged, even if the box 3 has a small capacity by providing the electromagnetic wave stirring members 9 and 11 to suppress the irregular reflection of the electromagnetic wave, the electric field intensity of the electromagnetic wave is substantially averaged over time and the measurement accuracy is improved. Can be improved.

Further, in an application for measuring the shield characteristic of the electronic device 7 to be measured, the shield characteristic can be effectively measured even if the electronic device 7 to be measured has a three-dimensional shape.

The above description is based on the two electromagnetic stirring members 9.1
1 is arranged so that its axis is directed in the X-axis direction and the Y-axis direction, and each is rotated at a different rotation speed to reduce the resonance phenomenon of the electromagnetic wave, lower the Q value, and reduce the electric field of the electromagnetic wave in the box 3. Although the strength was almost constant, Box 3
An electromagnetic wave absorber such as a sintered ferrite plate is attached to each inner surface, or a plurality of flexible metal bands are attached in the box 3 to reduce the electromagnetic wave resonance phenomenon in the box 3 and reduce the electric field strength of the electromagnetic wave. Averaging may be performed to make it almost constant.

In box 3, the respective axes are the X axis and the Y axis.
Three electromagnetic wave stirring means may be provided so as to face the axis and the Z axis.

As a result, the present invention is suitable for pre-measurement of a main test in which the device itself is miniaturized and the resistance and shield characteristics of various electronic devices are measured properly, and the electric field strength of the electromagnetic wave in the inside is averaged over time. Thus, it is possible to measure the resistance and the shield characteristics of various devices to be measured almost accurately. Further, the present invention can reduce the measurement cost.

[Brief description of the drawings]

FIG. 1 is a schematic perspective view of a simplified electromagnetic wave measurement box.

FIG. 2 is a chart showing an example of an electric field intensity at the center of a simplified electromagnetic wave measurement box when the electromagnetic wave stirring member is not operated.

FIG. 3 is a chart showing an example of the electric field strength at the center of the simplified electromagnetic wave measurement box when the electromagnetic wave stirring member is operated.

FIG. 4 is a chart showing a relationship between input power obtained in a simplified electromagnetic wave measurement box and expected electric field strength (average).

[Explanation of symbols]

1- Box for simple electromagnetic wave measurement, 3-box, 7-
Electronic equipment to be measured, 9/11-electromagnetic wave stirring member as electromagnetic wave stirring means, 13-measuring table, 17-transmission antenna as transmission means

Claims (5)

[Claims] 1. A metal box having a small-capacity space corresponding to a frequency band of an electromagnetic wave used for measurement, and an electronic device to be measured set on a measuring table arranged in the center of the space of the box. A transmitting unit that is provided near the electronic device to be measured and outputs an electromagnetic wave having a predetermined frequency band and output;
An electromagnetic wave stirrer disposed in the box and reflecting electromagnetic waves output from the transmitter and reflected in the box to reduce an electromagnetic wave resonance phenomenon, transmitted from the transmitter and acting on the electronic device to be measured. A simplified electromagnetic wave measurement box in which the electric field intensity of an electromagnetic wave is substantially averaged over time so that a limit value of resistance of the electronic device to be measured can be measured. 2. A metal box having a small-capacity space corresponding to a frequency band of an electromagnetic wave used for measurement, and an electronic device to be measured set on a measuring table arranged in the center of the space of the box. Transmitting means for outputting an electromagnetic wave having a predetermined frequency band and output, provided in the electronic device to be measured, and a box provided at a predetermined measurement interval with respect to the electronic device to be measured, Receiving means for receiving the transmitted electromagnetic wave, and electromagnetic wave stirring means arranged in the box, which reflects the electromagnetic wave output from the transmitting means and reflected in the box to reduce the electromagnetic wave resonance phenomenon,
A simplified electromagnetic wave measurement box in which the electric field intensity of an electromagnetic wave transmitted from a transmission means and transmitted through an electronic device to be measured is substantially averaged over time to enable measurement of a shield characteristic of the electronic device to be measured. 3. A metal disk according to claim 1 or 2, wherein each of the electromagnetic wave stirring means is arranged with their axes orthogonal to each other, and a plurality of notches are provided at predetermined intervals in a circumferential direction. A simple electromagnetic wave measurement box consisting of an electric motor that rotates a metal disk at different rotational speeds. 4. A simplified electromagnetic wave measuring box according to claim 1, wherein the electromagnetic wave stirring means comprises an electromagnetic wave absorber provided on the inner surface of the box. 5. A simplified electromagnetic wave measuring box according to claim 1, wherein the electromagnetic wave stirring means is comprised of a plurality of metal bands mounted in the box.