JP2004163372A - Measuring apparatus for electromagnetic waves - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an apparatus for measuring electromagnetic waves which can accurately measure the intensity of an electromagnetic wave. <P>SOLUTION: The electromagnetic wave measuring apparatus includes an anechoic chamber, constituted of a wall surface for absorbing the electromagnetic waves to form a regular hexagonal shape region isolated from an external world, a turntable disposed at the center of the regular hexagon shape for placing a device to be measured for radiating the waves, three antennas disposed on a straight line for connecting each mid-point of every other three sides of the six sides of the hexagonal shape to the central position of the hexagonal shape so that the directional gain in a direction perpendicular to the line is substantially zero, and a radio wave absorbing plate disposed between the three antennas to absorb the wave. Since in this constitution, the paths of the waves reflected once and received by the antenna 26 are only two paths L2 and the directional gains of the antenna 26 in the direction of this path is substantially zero, and accordingly, the components of these waves do not affect the intensities of the waves to be measured. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an electromagnetic wave measuring device in which an antenna and a device to be measured are arranged inside an anechoic chamber and the intensity of electromagnetic waves emitted by the device to be measured is measured.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, an electromagnetic wave measuring device configured by disposing an antenna inside an anechoic chamber has been used for measuring electromagnetic waves radiated from a device to be measured such as an electronic device.
[0003]
FIG. 3 shows an example of the electromagnetic wave measuring apparatus 10 according to the related art. In the electromagnetic wave measuring apparatus 10, an antenna support 14 is installed inside an anechoic chamber 12 surrounding a rectangular area, and one antenna 16 is mounted on the antenna support 14 and placed on a rotating turntable 18. The measurement of the electromagnetic wave radiated by the measured device 19 is performed. In this electromagnetic wave measurement, measurement is performed using a different type of antenna 16 for each frequency band, and it is necessary to change the plane of polarization by rotating the antenna 16 or the like. Therefore, during the measurement, an operator performs an operation of replacing the antenna 16 or changing a polarization plane of the antenna 16.
[0004]
An example of another conventional electromagnetic wave measuring device is disclosed in Japanese Patent Application Laid-Open No. 2001-116785. In this electromagnetic wave measuring device, a turntable is arranged in an anechoic chamber or open site, and a plurality of electromagnetic waves radiated by a device to be measured mounted on the turntable are set at a predetermined measurement distance from the turntable. It is measured using an antenna. In this electromagnetic wave measuring apparatus, since the electromagnetic wave is measured by a plurality of antennas at the same time, there is an advantage that the work of replacing the antenna and changing the plane of polarization can be saved and the measuring time of the electromagnetic wave can be shortened.
[0005]
[Patent Document 1]
JP 2001-116785 A
[Problems to be solved by the invention]
In the above-described measurement of the electromagnetic wave intensity, it is ideal and preferable to measure only the electromagnetic waves that directly fly directly from the device to be measured. However, actually, there is an electromagnetic wave that is reflected on the wall surface of the anechoic chamber and reaches the antenna, which affects the measurement accuracy. Among such electromagnetic waves, the intensity of the electromagnetic wave reflected twice or more on the wall surface is sufficiently small, and hardly affects measurement accuracy. However, the electromagnetic wave reflected only once on the wall of the anechoic chamber has a non-negligible intensity, and has a problem that the measurement accuracy of the electromagnetic wave intensity is affected. In the technology disclosed in JP-A-2001-116785, the shape of the anechoic chamber is not specified, but a similar problem may occur.
[0007]
Further, in the technique disclosed in Japanese Patent Application Laid-Open No. 2001-116785, since a plurality of antennas are arranged side by side, there is a problem that electromagnetic coupling between the antennas occurs and affects the accuracy of electromagnetic wave measurement. .
[0008]
The present invention has been made in view of the above-described problems, and has as its object to provide an electromagnetic wave measuring device that can accurately measure electromagnetic wave intensity.
[0009]
[Means for Solving the Problems]
In order to achieve the above object, the present invention is an electromagnetic wave measuring device for measuring the intensity of an electromagnetic wave emitted by a device under test, comprising an electromagnetic wave absorbing wall surface, a regular hexagonal shape isolated from the outside world An anechoic chamber forming an area of the above, a turntable arranged at the center of the regular hexagonal shape for mounting a device to be measured that radiates electromagnetic waves, and three every three sides of the six sides of the regular hexagonal shape. Three antennas arranged on a straight line connecting each midpoint of the side and the center position of the regular hexagonal shape, and three antennas having a directional gain in a direction perpendicular to the straight line being substantially zero, and being arranged between the three antennas; And a radio wave absorbing plate for absorbing electromagnetic waves.
[0010]
With such a configuration of the electromagnetic wave measuring device, the electromagnetic wave that is reflected once on the wall of the anechoic chamber and reaches the antenna is received by the antenna from a direction in which the directional gain of the antenna is almost zero. It is possible to prevent the reflected electromagnetic wave from affecting the measurement accuracy. Further, since the radio wave absorbing plate is disposed between the plurality of antennas, electromagnetic coupling between the antennas can be prevented.
[0011]
It is also preferable that the radio wave absorbing plate is arranged so that its plate surface is aligned with a straight line passing through the center of the regular hexagon. By arranging the radio wave absorbing plate in this way, the electromagnetic wave radiated from the device to be measured is not reflected by the radio wave absorbing plate. Therefore, the electromagnetic wave is prevented from being reflected by the radio wave absorbing plate and reaching the antenna.
[0012]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0013]
FIG. 1 is a configuration diagram illustrating a schematic configuration of an electromagnetic wave measurement device 20 according to an embodiment of the present invention. FIG. 1 is a diagram of the electromagnetic wave measuring device 20 as viewed from above.
[0014]
In the electromagnetic wave measuring device 20, a plurality of wall surfaces having a characteristic of absorbing radio waves are arranged at positions of each side of a regular hexagon, so that an anechoic chamber 22 is formed. The area inside the regular hexagonal shape of the anechoic chamber 22 is an isolated area where electromagnetic waves do not come from the outside. The area above this area is covered with a ceiling that absorbs radio waves.
[0015]
At the center of the regular hexagonal area inside the anechoic chamber 22, a turntable 28 on which a device to be measured can be mounted and made of a non-conductive material is arranged. The turntable 28 rotates at a predetermined speed around the center of the anechoic chamber 22 as a rotation axis. An antenna 26 for measuring electromagnetic waves is arranged on each straight line L1 connecting the center of the anechoic chamber 22 and the midpoints of every other three sides of the six sides of the anechoic chamber 22. . The antenna 26 is, for example, a horn antenna or a double ridged antenna. All the antennas 26 are arranged at a predetermined measurement distance r1 from the center of the anechoic chamber 22 so that measurement can be performed under the same conditions. These antennas 26 are attached to the antenna support 24, respectively. The antenna 26 can be attached / detached to / from the antenna support 24, and its attachment height and polarization plane can also be adjusted. A spectrum analyzer 32 is connected to each antenna 26, and can measure the intensity of electromagnetic waves emitted by the device under test. In addition, a radio wave absorbing plate 30 for preventing electromagnetic coupling between the antennas 26 is arranged in the middle of each antenna 26. The radio wave absorbing plate 30 is arranged with its plate surface aligned with a straight line passing through the center of the radio wave anechoic chamber 22. When the three antennas 26 are arranged inside the anechoic chamber 22 as described above, the measurement by the three antennas can be performed at the same time, so that the efficiency of the measurement operation and the measurement time can be improved.
[0016]
Next, the operation of the electromagnetic wave measuring device 20 according to the present embodiment having the above-described configuration to prevent the measurement accuracy of the electromagnetic wave intensity from lowering will be described. FIG. 2 shows a situation when the electromagnetic wave radiated from the device under test 34 is measured using the electromagnetic wave measuring device 20 of FIG. In FIG. 2, the antenna 26 is represented by a dot. The antenna 26 has directivities A1 and A2 in the center direction and the wall direction of the anechoic chamber 22, and the directional gain in a direction perpendicular to a straight line connecting the antenna 26 and the center of the anechoic chamber 22 is almost zero.
[0017]
At the time of measurement, since the turntable 28 rotates, the electromagnetic waves radiated from the device under test 34 are radiated in all directions in the anechoic chamber 22. At this time, the electromagnetic wave directly radiated from the device under test 34 to the antenna 26 is an electromagnetic wave to be measured by the antenna 26, but a part of the electromagnetic wave is reflected once by the wall surface of the anechoic chamber 22 and reaches the antenna 26. I do. In the present embodiment, the anechoic chamber 22 has a hexagonal shape, and the position where the antenna 26 is disposed is on a straight line connecting the center of the anechoic chamber and the midpoint of the wall. The paths of the received electromagnetic waves are only two paths L2 shown in the figure. Further, the direction in which the two-path electromagnetic waves are received by the antenna 26, that is, the direction approximately perpendicular to the straight line connecting the center and the midpoint, is almost zero because the directional gain of the antenna 26 is almost zero. The components do not affect the intensity of the electromagnetic wave to be measured, and a decrease in measurement accuracy is prevented.
[0018]
Further, in the present embodiment, since the radio wave absorbing plate 30 is disposed between the antennas 26, the influence of the antennas 26 on each other on the coupling of the antennas 26, that is, the reception characteristics of the electromagnetic waves is reduced. Of the measurement accuracy is prevented. Further, in the antenna 26, since the plate surface of the radio wave absorbing plate 30 is arranged so as to be aligned with a straight line passing through the center position of the regular hexagon, the electromagnetic wave is not reflected by the radio wave absorbing plate 30. That is, there is no reflection of the electromagnetic wave in the direction of the antenna 26 by the radio wave absorbing plate 30, and also in this respect, a decrease in measurement accuracy is prevented.
[0019]
The preferred embodiment of the present invention has been described above, but the present invention is not limited to the above embodiment, and various modifications can be made within an equivalent range. For example, a radio wave absorber may be laid on the floor to prevent electromagnetic waves from being reflected by the floor and received by the antenna 26.
[0020]
【The invention's effect】
In the present invention, the antenna is arranged on a straight line connecting the center of the anechoic chamber and the midpoint of one wall inside the regular hexagonal shaped anechoic chamber, and the directivity of the antenna is almost perpendicular to the straight line. Since it is zero, it is possible to prevent a decrease in the measurement accuracy of the electromagnetic wave intensity due to the electromagnetic wave reflected on the wall surface of the anechoic chamber.
[0021]
Further, since the radio wave absorbing plate is disposed between the antennas, the coupling between the antennas is reduced, and a decrease in the measurement accuracy of the electromagnetic wave intensity can be prevented.
[Brief description of the drawings]
FIG. 1 is a configuration diagram illustrating a schematic configuration of an electromagnetic wave measurement device according to an embodiment of the present invention.
FIG. 2 is an explanatory diagram showing a situation when measuring an electromagnetic wave radiated from a device to be measured.
FIG. 3 is a configuration diagram showing a schematic configuration of an electromagnetic wave measuring device according to a conventional technique.
[Explanation of symbols]
10, 20 electromagnetic wave measuring device, 12, 22 anechoic chamber, 14, 24 antenna support, 16, 26 antenna, 18, 28 turntable, 30 radio wave absorbing plate, 32 spectrum analyzer, 34 device to be measured.

Claims (2)

An electromagnetic wave measuring device for measuring the intensity of electromagnetic waves emitted by the device under test,
An anechoic chamber composed of walls absorbing electromagnetic waves and forming a regular hexagonal area isolated from the outside world;
A turntable for placing a device to be measured that radiates an electromagnetic wave, which is arranged at the center of the regular hexagonal shape,
The regular hexagonal shape is arranged on a straight line connecting each midpoint of every other three sides of the six sides of the regular hexagonal shape and the center position of the regular hexagonal shape, and the directivity gain in a direction perpendicular to the straight line is substantially zero. There are three antennas,
A radio wave absorbing plate arranged between the three antennas and absorbing electromagnetic waves;
An electromagnetic wave measuring device comprising: The electromagnetic wave measuring device according to claim 1,
The electromagnetic wave measuring device is characterized in that the radio wave absorbing plate is arranged so that its plate surface is aligned with a straight line passing through the center of the regular hexagon.

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