JP2002107398A - Measuring device for antenna-coupled state, and usage for radio wave anechoic chamber - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a 'silent' electromagnetic wave environment which is equivalent to an open site, using a radio wave anechoic chamber. SOLUTION: A radio wave absorbing body 10d is placed on a floor face 10c, located between a transmission antenna 12 and a reception antenna 14. The reception antenna 14 is preferably placed in a quiet zone. The transmission antenna 12 and the reception antenna 14 are preferably placed close to the diagonal line of the floor face 10c.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an antenna coupling state measuring device for measuring a coupling state between a plurality of antennas and a method for using an anechoic chamber.

[0002]

2. Description of the Related Art Conventionally, EMI (Electromagnetic Int.
calibration of the antenna coefficient of the measurement antenna
It was performed at an open site in accordance with NSI (American Standards Association) standard C63.4-1992. An open site is an outdoor site provided in a place where there is no electromagnetic wave source around, for example, a remote mountainous area.When calibrating the antenna coefficient, a signal generator, transmitting antenna, receiving antenna and measurement Prepare the container. Further, the signal generated by the signal generator is propagated from the transmission antenna to the reception antenna, and the reception output of the reception antenna is measured and analyzed by a measuring instrument such as a spectrum analyzer. Then, based on the result of the measurement and analysis, the antenna coefficient of the receiving antenna which is the EMI measurement antenna is calibrated.

[0003]

Here, the EMI measuring antenna is manufactured and used in an environment where electromagnetic interference is likely to occur, and such an environment is generally used in cities, densely populated areas, industrial areas, and the like. It is in. On the other hand, the configuration of the antenna coefficient of the EMI measurement antenna needs to be performed in a remote mountainous area. Therefore, conventionally, in order to calibrate the antenna coefficient of the antenna for EMI measurement, it is necessary to go from a city area or the like to a mountain area or the like, which is troublesome. In addition, since the site is an outdoor site, when the weather changes, the electromagnetic wave environment changes and the measurement conditions change. That is, there is a problem that the implementation is restricted by the weather and the like.

[0004] On the other hand, conventionally, a closed room which is electromagnetically shielded from the outside and provided with a radio wave absorber on an inner wall surface is called an anechoic chamber, and is used for various tests and measurements related to electromagnetic waves. For example, when measuring an electromagnetic wave radiated from a device such as a personal computer, a device to be measured and a receiving antenna for receiving the electromagnetic wave radiated from the device are installed in an anechoic chamber, and the receiving antenna is installed. Measures and analyzes the received output of Since the anechoic chamber can be provided in cities, etc., if the anechoic chamber can be used to calibrate the antenna coefficient of the antenna for EMI measurement, it is not necessary to go to a remote mountainous area. This is advantageous in terms of cost and cost. Further, the inside of the anechoic chamber is less affected by weather and the like than the outdoor site.

[0005] However, the anechoic chamber conventionally used for measurement of unnecessary radiation has a structure capable of electromagnetically shielding the inside and outside of the chamber and has a radio wave absorber therein, but is comparable to an open site. It cannot provide an electromagnetic environment as quiet as possible. In other words, when a transmitting and receiving antenna is installed in an anechoic chamber and an electromagnetic wave is transmitted from the transmitting antenna, reflection from the floor surface where no radio wave absorber is provided and, to a lesser extent, radio wave absorption on the inner wall surface and ceiling Reflections from the body occur. The presence of these reflections is equivalent to the presence of an unnecessary electromagnetic wave source in the surroundings, so that in the conventional anechoic chamber, the calibration of the antenna coefficient of the EMI measurement antenna could not be performed with high reliability and accuracy. .

SUMMARY OF THE INVENTION The present invention has been made to solve such problems, and has been devised by devising the arrangement of devices in an anechoic chamber and the use form of the anechoic chamber.
An object of the present invention is to make it possible to perform a measurement conventionally performed at an open site, such as a measurement relating to calibration of an I measurement antenna coefficient, using an anechoic chamber.

[0007]

In order to achieve such an object, an antenna coupling state measuring apparatus according to the present invention comprises:
(1) An antenna coupling state measuring apparatus including a measuring system for coupling a transmitting antenna and a receiving antenna by an electromagnetic wave and measuring the coupling state, (2) the transmitting and receiving antennas are electromagnetically shielded from the outside. (3) the closed room includes reflection propagation suppressing means for suppressing the influence of the electromagnetic wave reflection by the side wall surface, the ceiling, and the floor surface of the closed room on the receiving antenna. I do. In addition, the method for using an anechoic chamber according to the present invention includes: (1) an anechoic chamber in which an electromagnetic wave is shielded from the outside and a radio wave absorber is disposed on the inner surface to measure the coupling state of the antenna; The antenna arrangement or the polarization plane or the position of the radio wave absorber in the anechoic chamber is set so that the open site environment is simulated.

As described above, in the antenna coupling state measuring apparatus according to the present invention, not only the side wall and the ceiling of the closed room electromagnetically shielded from the outside but also the reflection on the floor, the influence of the reflection on the receiving antenna. Has been suppressed. Therefore, a situation where the reflection of the electromagnetic wave transmitted from the transmitting antenna acts as an unnecessary electromagnetic wave source is less likely to occur than in the conventional anechoic chamber. Further, in the method of using the anechoic chamber according to the present invention, by setting the position of the antenna or the position of the polarization plane or the radio wave absorber in the anechoic chamber, by simulating an open site environment in the anechoic chamber I have. An open site here refers to an isolated electromagnetic wave environment in which there are no unnecessary electromagnetic wave sources around,
Simulated formation does not mean realizing isolation directly by means such as providing it in a remote mountainous area, but realizing isolation substantially by means such as suppressing the reflection from the floor surface. It is. That is, in the method of using the anechoic chamber according to the present invention, the situation where the reflection of the electromagnetic wave transmitted from the transmission antenna acts as an unnecessary electromagnetic wave source hardly occurs.

Therefore, according to the present invention, the electromagnetic wave environment that is the same as or close to the open site is realized by the facilities that can be provided on one floor of a building near the city, such as an anechoic chamber. And calibration of the antenna coefficient of the EMI measurement antenna can be performed without much trouble, time and cost, and without being affected by the weather or the like.

Furthermore, the reflection propagation suppressing means can be easily realized by devising the arrangement of the radio wave absorber, devising the antenna arrangement, devising the polarization plane of the antenna, and the like. For example, a radio wave absorber that absorbs incident electromagnetic waves is installed on the entire side wall surface and ceiling of a closed room (anechoic chamber) and at least a part of the floor surface. Installed at least on a part of the floor surface between the position directly below the installation position of the transmission antenna and the position directly below the installation position of the reception antenna so that the primary reflected wave by the floor surface among the electromagnetic waves transmitted and received by the reception antenna is suppressed. I do. Such a reflection propagation suppressing means does not require precise setting of the antenna position in a closed room (an anechoic chamber), and is therefore easy to implement. As a method of realizing the reflection propagation suppressing means by devising the antenna position, first, there is a space region where the intensity ratio of the reflected wave due to the inner surface of the closed room (radio dark room) to the direct wave from the transmitting antenna is the smallest. There is a method of installing a receiving antenna in a quiet zone. Second, there is a method of setting the positions of the transmitting and receiving antennas so that reflected waves from different portions of the inner surface of the closed room (anechoic chamber) do not emphasize each other at the installation position of the receiving antenna. As for the latter, a method of setting the polarization planes of the transmitting and receiving antennas instead or in combination may be used.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The basic concept of the present invention will be described below with reference to specific examples, and then preferred embodiments of the present invention will be described with reference to the drawings.

First, one of the basic ideas of the present invention is that an antenna coefficient calibration of an antenna for EMI measurement, which has been conventionally performed at an open site, can be provided in a suburb of a city or the like, and the influence on the climate can be reduced. The point is that it can be performed using an anechoic chamber that is difficult to perform. If the system for calibrating the antenna coefficient of the antenna for EMI measurement is to be realized by simply using an anechoic chamber conventionally used for other purposes, the arrangement of the apparatus will be as shown in FIG.

In FIG. 1, reference numeral 10 denotes an anechoic chamber, and its side wall surface 10a, ceiling 10b, and floor surface 10c are usually formed of metal or the like for electromagnetic shielding against the outside. On the side wall surface 10a and the ceiling 10b of the anechoic chamber 10, a radio wave absorber 10 that acts to absorb electromagnetic waves and convert them into heat is provided.
d is arranged. In the anechoic chamber 10, a transmitting antenna 12 and a receiving antenna 14, which constitute a measurement system,
Outside the anechoic chamber 10, a signal generator 16 and a spectrum analyzer 18 are arranged, respectively. The transmitting antenna 12 and the receiving antenna 14 are supported and fixed by supports 20 or 22, respectively, and are connected to a signal generator 16 or a spectrum analyzer 18 via coaxial cables 24 and 26, respectively. Accordingly, the high-frequency signal generated by the signal generator 16 is supplied to the transmission antenna 12 via the coaxial cable 24, whereby the electromagnetic wave radiated from the transmission antenna 12 is received by the reception antenna 14, and the high-frequency signal received by the reception antenna 14 The signal is transmitted to the spectrum analyzer 1 via the coaxial cable 26.
8 for frequency component measurement and analysis.

In the drawings, reference numerals 28 and 30 denote support stands for supporting the coaxial cables 24 and 26 substantially horizontally.
The coaxial cables 24 and 26 are guided to the outside of the radio wave anechoic chamber 10 through the radio wave absorber 10d arranged on the side wall surface 10a or through the back side thereof. These are a transmission antenna 12 and a reception antenna 14 and a coaxial cable 24.
And 26 are effective in suppressing the coupling with.

When measurement and analysis for antenna coefficient calibration are performed in the configuration shown in FIG.
0a, the ceiling 10b, and the floor 10c reflect electromagnetic waves. That is, the electromagnetic wave radiated from the transmitting antenna 12 is directly received by the receiving antenna 14 on the one hand, but is received by the receiving antenna 14 after being reflected by the side wall surface 10a, the ceiling 10b or the floor surface 10c on the other hand. You. The former, that is, the reflected wave is an unnecessary wave with respect to the former, that is, the direct wave. In particular, since the direct wave and the reflected wave originate from the same signal generator 16 and the transmitting antenna 12 in the first place, the reflected wave has a strong correlation with the direct wave. Sex also matters. The occurrence of such an unnecessary wave is the same as the appearance of an unnecessary electromagnetic wave source in the receiving-side measuring device (the spectrum analyzer 18 in the illustrated example). Therefore,
In order to realize an electromagnetic wave environment as quiet as an open site, it is necessary to provide an effective means for reflection by the side wall surface 10a, the ceiling 10b, or the floor surface 10c. In particular, the radio wave absorber 10d is absorbed by the side wall surface 10a and the ceiling 10b to suppress the reflection. However, in the conventional anechoic chamber 10, the floor surface 10c is merely a metal surface. I can't ignore it.

The present invention has an aspect of providing an effective means for preventing reflection by the side wall surface 10a, the ceiling 10b, or the floor surface 10c. In the first embodiment shown in FIG. 2, the arrangement of the radio wave absorber 10d is devised, and in the second embodiment shown in FIG. 3, the position of the reception antenna 14 with respect to the anechoic chamber 10 and the transmission antenna 12 is devised. In the third embodiment shown in FIG. 4, this aspect is exhibited by devising the setting of the positions of the anechoic chamber 10 and the transmitting antenna 12 and the receiving antenna 14 or devising the setting of the polarization plane of the transmitting antenna 12 and the receiving antenna 14. In addition,
In the following description, the same reference numerals are given to components corresponding to or the same as the configurations shown in FIG. 1, and redundant description will be omitted. Further, members and portions similar to those of the configuration shown in FIG. 1 such as a device arranged outside the anechoic chamber 10 and a cable route inside and outside the anechoic chamber 10 are not shown.

First, in the first embodiment shown in FIG. 2, the radio wave absorber 10d is also arranged on the floor 10c. The radio wave absorber 10d is arranged on the floor 10c so that at least the primary reflected wave is absorbed and sufficiently suppressed. The primary reflected wave referred to here is a primary reflected wave from the floor 10c, that is, an electromagnetic wave transmitted from the transmitting antenna 12, reflected by the floor 10c, and reaching the receiving antenna 14 without being reflected at other places. Therefore, the location of the radio wave absorber 10d on the floor surface 10c in this embodiment is mainly at the location from the leg of the support 20 to the leg of the support 22, that is, from immediately below the transmitting antenna 12 to immediately below the receiving antenna 14. It is everywhere. By arranging the radio wave absorber 10d at this location, it is possible to effectively suppress the reflected wave from the floor surface 10c, particularly the primary reflected wave which is the most likely to be a problem. However, a certain effect can be obtained even if the radio wave absorber 10d is arranged at a location other than this. Also, by making the radio wave absorber 10d portable, it is possible to easily cope with a change in the antenna position (for example, a change in the antenna interval) in the radio wave anechoic chamber 10.

Next, in the second embodiment shown in FIG. 3, the receiving antenna 14 is arranged in the quiet zone 32. The quiet zone 32 is a space region in which the intensity ratio of the reflected wave to the direct wave is a minimum or a value close thereto.
That is, it is a space area in which reflected waves are suppressed as compared with other space areas in the anechoic chamber 10. The position where the quiet zone 32 appears is determined by the size and internal structure of the anechoic chamber 10, the three-dimensional position of the transmitting antenna 12 with respect to the anechoic chamber 10, and the like. For example, the structure of the anechoic chamber 10 is determined and the position of the transmitting antenna 12 is determined. It can be known by actual measurement in a determined state or by numerical calculation. In the present embodiment, by arranging the receiving antenna 14 in the quiet zone 32, the influence of the reflected wave is suppressed, and an environment closer to an open site is realized. Further, the present embodiment has an excellent surface as compared with the first embodiment in that it is effective not only for the reflection by the floor surface 10c but also for the reflection by the side wall surface 10a and the ceiling 10b. are doing. Further, the present embodiment can be implemented in a form combined with the first embodiment.

Further, in the third embodiment shown in FIG. 4, the transmitting antenna 12 and the receiving antenna 14 are arranged immediately above the diagonal line 34 of the floor 10c of the anechoic chamber 10. In such an arrangement, the receiving antenna 1 is radiated from the transmitting antenna 12 and reflected by the upper side wall surface 10a in the figure.
4 and the second primary reflected wave radiated from the transmitting antenna 12 and reflected by the lower side wall surface 10a in the figure and reaching the receiving antenna 14 always have different wireless propagation path lengths. Therefore, in general, the phases are different upon arrival at the receiving antenna 14. On the other hand, suppose that the transmitting antenna 12 and the receiving antenna 14 are connected to the floor 1 of the anechoic chamber 10.
0c (the upper and lower side wall surfaces 1 passing through the intersection of the diagonal lines)
(A straight line parallel to 0a), the first and second primary reflected waves described above have the same radio propagation path length, so that their phases upon arrival at the receiving antenna 14 are equal, In the receiving antenna 14, both will strengthen each other. In the present embodiment, since the phases upon arrival at the receiving antenna 14 are generally different, the probability that the first and second primary reflected waves are strengthened at the receiving antenna 14 is low. Thereby, the influence of the reflected wave can be suppressed. In addition,
This embodiment can be implemented in a form combined with the first and second embodiments. In the above description, the effect was described by focusing on the planar positional relationship, that is, the arrangement of the floor surface 10c on the diagonal line 34, and focusing on the primary reflection by the upper and lower side wall surfaces 10a in the figure. The configuration shown in FIG. 4 is also effective for primary reflection by the ceiling 10b and the floor surface 10c and higher-order reflection on each surface. Further, similar effects can be obtained by appropriately setting the heights of the transmitting antenna 12 and the receiving antenna 14 and by shifting the plane of polarization of the receiving antenna 14 by an appropriate angle with respect to the plane of polarization of the transmitting antenna 12. Can be. In addition, the device for setting the height and the plane of polarization can be combined with the device for arrangement shown in FIG.

[0020]

As described above, according to the present invention,
The situation where the reflection of the electromagnetic wave transmitted from the transmitting antenna acts as an unnecessary electromagnetic wave source is unlikely to occur, and an open site environment can be simulated.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing the arrangement and structure of devices inside and outside an anechoic chamber.

FIG. 2 is a longitudinal sectional view showing a radio wave absorber arrangement according to the first embodiment of the present invention.

FIG. 3 is a longitudinal sectional view showing an antenna arrangement according to a second embodiment of the present invention.

FIG. 4 is a cross-sectional view illustrating an antenna arrangement according to a third embodiment of the present invention.

[Explanation of symbols]

10 Anechoic chamber, 10a Side wall surface, 10b ceiling, 10
c floor, 10d radio wave absorber, 12 transmitting antennas,
14 receiving antennas, 16 signal generators, 18 spectrum analyzers, 32 quiet zones, 34 diagonals.

Continued on the front page (72) Inventor Yutaka Komatsu 2-26-10 Tenjin, Nagaokakyo-shi, Kyoto F-term in Murata Manufacturing Co., Ltd. (reference) 5E321 AA42 BB02 GG05 GG11 5J020 BD01 BD02 5J046 AA01 AA05 AA19 UA04 UA09

Claims (6)

[Claims] 1. An antenna coupling state measuring device comprising a measuring system for coupling a transmitting antenna and a receiving antenna by electromagnetic waves and measuring the coupling state, wherein the transmitting and receiving antennas are electromagnetically shielded from the outside. An antenna coupling state, wherein the closed chamber is provided with a reflection propagation suppressing means for suppressing an influence of the reflection of electromagnetic waves by the side wall surface, the ceiling, and the floor surface of the closed room on the receiving antenna. Measuring device. 2. The antenna coupling state measuring apparatus according to claim 1, wherein said reflection propagation suppressing means is provided on at least a part of a side wall and a ceiling of said closed room and at least a part of said floor to absorb an incident electromagnetic wave. An antenna coupling state measuring device including an absorber. 3. The antenna coupling state measuring device according to claim 2, wherein the electromagnetic wave transmitted from the transmitting antenna and received by the receiving antenna is subjected to radio wave absorption on the floor such that a primary reflected wave by the floor is suppressed. An antenna coupling state measuring device, wherein the body installation site includes at least a site on the floor between the position immediately below the installation position of the transmission antenna and the immediately below the installation position of the reception antenna. 4. The antenna coupling state measuring device according to claim 1, wherein the reflection propagation suppressing means has the smallest intensity ratio of the reflected wave by the inner surface of the closed chamber to the direct wave from the transmitting antenna. An antenna coupling state measuring apparatus, comprising: the receiving antenna installed in a quiet zone which is a spatial area. 5. The antenna coupling state measuring device according to claim 1, wherein the reflection propagation suppressing means is configured such that reflected waves from different portions of the inner surface of the closed room are different from each other at an installation position of the receiving antenna. An antenna coupling state measuring device comprising the transmitting and receiving antennas whose positions are set or their polarization planes are set so as not to be emphasized. 6. An open-site environment is simulated in an anechoic chamber to measure the coupling state of an antenna by using an anechoic chamber in which an electromagnetic wave absorber is disposed on the inner surface which is electromagnetically shielded from the outside. A method of using an anechoic chamber, wherein the arrangement of the antenna or the position of the polarization plane or the position of the radio wave absorber in the anechoic chamber is set.