JP5318026B2 - Method to identify electromagnetic shielding performance of electromagnetic shielding room - Google Patents

Description

  The present invention relates to a method for specifying electromagnetic shielding performance, and particularly relates to an electromagnetic shielding room in which conductive materials arranged on a wall surface of a building are connected to each other through a joint portion having a slit. The present invention relates to a method for specifying the electromagnetic shielding performance of an electromagnetic shielding room appropriately reflected as a component.

  In a semiconductor manufacturing room, hospital MRI examination room, etc., the wall surface is covered with a conductive material such as an iron plate or copper foil, or an electromagnetic shield door or electromagnetic shield window is installed to prevent leakage of radio waves from inside and outside the room. An electromagnetic shield room is provided.

  In general, the conductive material provided on the wall surface of the electromagnetic shield chamber covers all the wall surfaces in a posture in which a large number of seam portions are provided, for example, by overlapping conductive materials having a predetermined plane size. Here, the “wall surface” has a comprehensive meaning including a wall, a ceiling, a floor, a window, a door, and the like.

  As the form of the seam portion of the conductive material, two kinds of forms can be mainly mentioned. One form thereof is a form in which the superposed conductive materials are connected without gaps (slits) by soldering or welding.

  On the other hand, the other form is a form in which the adjacent conductive materials are overlapped and the overlapped portions are spot-fixed at regular intervals by screws, nails, staples or the like.

  From the viewpoint of suppressing leakage of radio waves from inside or outside the room, the former form, that is, a form in which the conductive materials are in close contact with each other without any gap is desirable.

  However, from the viewpoint of economics due to convenience in construction, shortening the construction period, construction costs, etc., the latter form in which the overlapping points are spot-fixed is often used. From the above tendency, the adoption of the latter form is even more remarkable.

  While the spot where the overlapping part is spot-fixed is excellent in workability and economical efficiency, the adhesion of the overlapping part is not guaranteed, so a slit is likely to occur here, and radio wave leakage from this slit is called A big problem arises.

  By the way, the performance design method of the electromagnetic shield room starts with “Understanding the performance from the material side of the conductive material used” and “Performance from the structural side due to the connection form of the connection point between the conductive materials. The general design flow goes to “Understanding” and “Understanding performance as viewed from the overall structure of the electromagnetic shield room”.

  Among these, with regard to “Performance grasp from the material aspect of the conductive material used” and “Performance grasp from the structural aspect due to the connection form of the connection place between the conductive materials”, in the relevant technical field Those skilled in the art can specify their performance based on past experience, public information, and experiments, and reflect them in the design. On the other hand, with regard to “performance grasp as seen from the overall structure as an electromagnetic shield room”, the virtual image method, which is a method of tracking the trajectory of radio waves reflected on the wall surface etc. in the interior, especially for architectural spaces, In many cases, a mirror image method, a ray tracing method, or the like (which can be collectively referred to as a “virtual image method”) is applied.

  In specifying the performance of the electromagnetic shield room, in the simulation using the virtual image method described above, the tracking of the light beam when the radio wave (light beam) propagates in a straight line from the radio wave source and is reflected (regular reflection) on the wall surface is specified. When this is applied to specify the performance of the electromagnetic shield room, the light beam transmitted through an arbitrary position on the electromagnetic shield surface is traced. Therefore, the simulation was performed under the premise that the entire target electromagnetic shield surface has uniform electromagnetic shielding characteristics without considering the actual electromagnetic shielding structure where light rays are transmitted. Yes.

  However, as described above, the actual electromagnetic shield surface is composed of a surface made of a conductive material and a joint portion that connects adjacent conductive materials. And, in the form of the seam portion where the overlapping portion is spot-fixed, the electromagnetic shielding performance is significantly reduced as compared with the surface made of the conductive material. This greatly affects the electromagnetic shielding performance of the entire electromagnetic shielding room.

  In the conventional virtual image method simulation, the slit formed by the joint portion is not reflected in the simulation regarding the electromagnetic shield room having the joint portion, particularly the joint portion where the overlapping portions of the conductive materials are spotted. Therefore, the electromagnetic shielding performance of the actual electromagnetic shielding room was not precisely specified.

  The present invention has been made in view of the above-described problems, and has a seam portion in which the overlapping portions of the conductive materials are spot-stopped. A method for specifying the electromagnetic shielding performance of an electromagnetic shielding room, which is appropriately reflected as a component of the electromagnetic shielding room, and thus can accurately specify the electromagnetic shielding performance of the electromagnetic shielding room as compared to the conventional identification method. It is intended to provide.

  In order to achieve the above object, according to the method of specifying electromagnetic shielding performance of an electromagnetic shielding room according to the present invention, a plurality of conductive materials are arranged on a wall surface of a building, and adjacent conductive materials are connected via a joint portion. In the electromagnetic shield room, the method for specifying the electromagnetic shield performance of the electromagnetic shield room in which at least one seam portion is provided with a slit, the method for specifying the electromagnetic shield performance includes: a setting step for setting various conditions; A tracking step of tracking a radio wave transmitted into the electromagnetic shield room and calculating an electric field strength at a receiving point in the electromagnetic shield room, wherein the setting step uses a radio wave source outside the electromagnetic shield room as a primary wave source. In this case, it is assumed that the slit from which the radio wave transmitted from the primary wave source is transmitted through the slit into the electromagnetic shield room is a secondary wave source. In both steps, the number of slits and the three-dimensional position are set, the directivity characteristics and polarization characteristics at the time of incidence of the transmitted radio wave from the primary wave source to the secondary wave source are set, and the secondary wave source characteristics are determined. Determining the transmitted radio wave characteristics by setting the transmission attenuation amount, directivity characteristics, polarization characteristics, and phase characteristics of the transmitted radio waves transmitted from the secondary wave source to the electromagnetic shield room, and the tracking step is based on the virtual image method. Based on this, the trajectory of the transmitted radio wave in the electromagnetic shield room is traced, and at least the electric field strength at the reception point in the electromagnetic shield room is calculated.

  The method for specifying the electromagnetic shielding performance of the present invention is based on the premise that the joint portion between the conductive materials constituting the electromagnetic shielding chamber for which the performance is to be specified includes at least one slit. In order to reflect in the design that the radio wave is transmitted into the room, this slit is used as a virtual secondary wave source, and the transmitted radio wave is propagated from the primary wave source, which is the radio wave source, to the secondary wave source and transmitted through the secondary wave source. Set the trajectory of the radio wave ray that the radio wave is transmitted into the room, determine the characteristics of these secondary wave sources and the characteristics of the transmitted radio wave appropriately, and perform electromagnetic shielding performance at the receiving point in the electromagnetic shielding room under virtual image method simulation For example, the electric field strength is calculated.

  In addition, the radio wave transmitted from the primary wave source into the room may be transmitted from a main radio wave transmission area (an area other than the slit) set at an arbitrary location on the wall surface. In this case, the main radio wave transmission area In addition, the transmission of radio waves from the slit (secondary wave source) at the joint is reflected in the virtual image method simulation. In addition, the transmitted radio wave reaching the reception point includes, for example, a transmitted radio wave that directly reaches from the secondary wave source and a transmitted radio wave that arrives after being reflected by the wall surface in the electromagnetic shield room.

  Since the present invention tracks the ray trajectory of the transmitted radio wave in the electromagnetic shield room based on the virtual image method, it is essential to set the number of slits and the three-dimensional coordinate position of each slit in the setting step. In addition, this slit may set only one place with respect to the electromagnetic shield room of simulation object, and may set two or more places. However, in an actual electromagnetic shield room, in view of having a large number of seams formed by overlapping each of a large number of conductive materials and spotting each overlapping portion, a plurality of slits and each of them are used in a virtual image method simulation. It is preferable to set a secondary wave source corresponding to the slit. By setting a plurality of slits in this way, the electromagnetic shielding performance of the electromagnetic shielding chamber can be specified more precisely.

  Furthermore, in order to determine the characteristics of the secondary wave source due to the slit, the secondary wave source characteristics are determined by setting the incident directivity characteristics and polarization characteristics.

  Further, in the setting step, in order to determine the characteristics of the transmitted radio wave, the transmission attenuation amount, directivity characteristic, polarization characteristic, and phase characteristic of the transmitted radio wave transmitted into the electromagnetic shield room are set.

  In the setting step, both the characteristics of the secondary wave source due to the slit and the characteristics of the transmitted radio wave transmitted from the secondary wave source into the room are determined, and in the tracking step based on the next virtual image method, these characteristics are determined. Is used to track the ray trajectory of the transmitted radio wave in the room, and the electric field strength at the receiving point set at an arbitrary place in the room is calculated.

  In actual virtual image method simulation, information on the radio wave source that is the primary wave source (coordinate position, etc.), information on the receiving point (coordinate position, etc.), the frequency of the target radio wave, and the electromagnetic wave viewed from the material side of the conductive material Shielding performance and reflection performance, electromagnetic shielding performance viewed from the structure surface of the slit, and the like are further set.

  In addition to the electric field strength at the reception point, the results calculated by the virtual image method simulation include the transmission status of the transmitted radio wave, the reflection status of the transmitted radio wave on the wall surface, and the arrival time characteristics at which the reflected transmitted radio wave reaches the reception point. Etc.

  According to the above-described method for specifying the electromagnetic shielding performance of the present invention, radio waves from the outside are transmitted into the room through the slit of the joint, that is, the slit is appropriately reflected as a component of the electromagnetic shielding room. A virtual image method simulation result is obtained.

  Here, the seam portion described above is basically provided with a linear connection structure between members such as a door and a frame, a window glass and a frame, etc., and in this structure, on the connection structure, It is a part where there is electrical resistance that cannot be ignored. And as a form of this joint part, the following forms can be mentioned, for example.

  One of them is a form in which adjacent conductive materials are overlapped and the overlapped portion is spot-stopped. The other is a form in which adjacent conductive materials are provided side by side, separate conductive materials are arranged so as to straddle them, and are overlapped, and the overlapping portions are spot-fixed. The other one is a form in which the ends of adjacent conductive materials are bent to form a bent portion, the two bent portions are overlapped, and the overlapped portion is spot-fixed.

  In addition, one end portion of the adjacent conductive material is bent to the other side or the opposite side to form a bent portion, and the bent portion and the other conductive material are overlapped, and the overlapping portion is a spot. In the fixed form, a concave groove is formed in one end region of the adjacent conductive material, the end region including the concave groove and the end region of the other conductive material are overlapped, and the overlapping portion is a spot. In a fixed form, a concave groove having a complementary shape is formed in the end regions of both conductive materials, and both end regions are overlapped in a posture in which the concave grooves of both adjacent conductive materials are positioned. There is a form in which the matching points are spot-fastened. In any of these various forms of joints, the slits are formed at the overlapping positions of adjacent conductive materials.

  In addition, as described above, “spot fastening” here refers to a seam structure in which conductive material is overlapped at fixed intervals with screws, nails, staples, etc., and slits are easily formed. It means connection form.

  As can be understood from the above description, according to the method for specifying the electromagnetic shielding performance of the electromagnetic shielding chamber of the present invention, the slit formed in the joint portion between the conductive materials is a secondary wave source, and the radio wave is the primary wave source. Electromagnetic shield of the actual electromagnetic shield room with slits by transmitting the transmitted radio wave propagated from the transmission source through this secondary wave source as a transmitted radio wave into the room and tracking the path of this transmitted radio wave by the virtual image method The performance can be specified precisely.

It is a flowchart of the method of specifying the electromagnetic shielding performance of this invention. (A) is the schematic diagram explaining the concept of the virtual image method, (b) is the schematic diagram explaining the view of reflective property. It is the schematic diagram which showed the electromagnetic shielding room which the seam part of an electroconductive material comprises a slit with a radio wave transmission source, the indoor receiving point, a transmission radio wave, and a transmission radio wave. (A), (b), (c), (d), (e), and (f) are all schematic views showing an example of an embodiment of a joint portion. It is a model figure which shows a virtual image method simulation model. (A) is the figure which simulated the electromagnetic shielding room used in experiment, (b) is the graph which showed the electric field strength measured value by experiment, and the specific value by the method of this invention.

  Embodiments of the present invention will be described below with reference to the drawings. The illustrated example for explaining the specifying method of the present invention shows the propagation of radio waves from “outdoor to indoor” as an example, but “indoor to outdoor” is of course applicable. . Furthermore, it is also possible to set “other structures that emit radio waves and are attenuated when transmitted” existing indoors or outdoors.

  FIG. 1 is a flowchart of a method for specifying the electromagnetic shielding performance of the present invention, FIG. 2a is a schematic diagram illustrating the concept of the virtual image method, and FIG. 2b is a schematic diagram illustrating the concept of reflective properties. Further, FIG. 3 is a schematic diagram showing an electromagnetic shield chamber in which a joint portion of a conductive material has a slit together with a radio wave transmission source, a reception point in the room, a transmission radio wave and a transmission radio wave.

  The specific method of the present invention is an electromagnetic shield in which a plurality of conductive materials are arranged on a wall surface (wall, ceiling, floor, window, door, etc.) of a building, and adjacent conductive materials are connected to each other via a joint portion. This is a method for specifying the electromagnetic shielding performance of an electromagnetic shielding chamber, wherein at least one seam has a slit.

  The identification method mainly includes a setting step S10 for setting various conditions, and a tracking step S20 for tracking the radio wave transmitted into the electromagnetic shield room and calculating the electric field strength at the reception point in the electromagnetic shield room. Has been.

  In the setting step S10 for setting various conditions, when the radio wave transmission source outside the electromagnetic shield room is used as the primary wave source, the slit from which the radio wave transmitted from the primary wave source is transmitted through the slit into the electromagnetic shield room Is a secondary wave source. The number of slits on the wall of the building to be simulated and the three-dimensional position of each slit are set, and the transmitted radio waves when the radio waves transmitted from the radio wave source (primary wave source) outside the electromagnetic shield room reach the slits. The incident directivity and polarization characteristics are set to determine the characteristics of the secondary wave source (step S1).

  This secondary wave source is not set to “one” for “one slit”, but a plurality of secondary wave sources are set on the slit in relation to the set slit length and the target frequency (wavelength). Is.

  Once the characteristics of this secondary wave source are determined, when performing virtual image method tracking from the secondary wave source, `` directional characteristics '', `` polarization characteristics '', `` phase characteristics '' are individually applied to each of the plurality of transmitted radio waves. To determine the characteristics of the transmitted radio wave (step S2). The basic electric field strength of the secondary wave source is set by subtracting the transmission attenuation from the intensity of the outgoing radio wave that has arrived at the secondary wave source.

  In addition to the determination of the characteristics of the secondary wave source and the transmitted radio wave described above, information on the radio wave source that is the primary wave source (coordinate position, etc.), information on the receiving point (coordinate position, etc.), frequency of the target radio wave, The electromagnetic shielding performance and reflection performance viewed from the material surface of the conductive material, the electromagnetic shielding performance viewed from the structure surface of the slit, and the like are further set.

  Once both the characteristics of the secondary wave source due to the slit and the characteristics of the transmitted radio wave transmitted from the secondary wave source into the room are determined in the setting step, these characteristics are then used in the tracking step based on the virtual image method. Then, trace the ray trajectory of the transmitted radio wave in the room and calculate the simulation result indicating the electromagnetic shielding performance (for example, the electric field strength at the receiving point set at any location in the room, the transmission status of the transmitted radio wave, the transmitted radio wave Reflection status on the wall surface, arrival time characteristics when the reflected transmitted radio wave reaches the receiving point, etc.).

  Here, a prediction simulation algorithm in the virtual image method will be outlined with reference to FIGS.

  First, regarding the distance propagation of the signal, the signal from the transmission point is set as a plane wave, and the electric field strength attenuates in inverse proportion to the square of the distance with respect to the propagation to the reception point.

  Next, with respect to the reflected signal, the “virtual image method” is applied to the reflected wave from each surface, as shown in FIG.

  As shown in FIG. 2b, regarding the reflection property on each surface, the electric field vector of the incident signal at the time of reflection on each surface is divided into a component (TM component) included in the incoming / reflected wavefront and a component parallel to the opposing wall surface ( (TE component) is vector-decomposed and the attenuation amount and phase change amount at the time of reflection are obtained for each. The decomposed signal propagates as it is, and when there is a next reflecting surface, it is further decomposed into a TM component and a TE component.

  Each signal that arrives at the reception point is synthesized in accordance with the setting directivity at the reception point. Here, the handling of the phase amount can be taken into account according to the result output content.

  The identification method of the present invention to which such a virtual image method is applied is applied to the specific evaluation of the electromagnetic shielding performance of the electromagnetic shielding chamber as shown in FIG. The electromagnetic shield room MS simulated in the figure has six wall surfaces including a wall, a ceiling, and a floor, and a door D and a window F are provided in a part thereof, and a large number of iron plates and copper foils are provided on the entire surface. Etc. are provided in a posture in which the conductive materials C,. The joint portion J is a connection form in which the adjacent conductive materials C and C are overlapped and the overlapping portion is spot-fixed or the like. Therefore, all or a part of the joint portion J has a slit. Is formed.

  In addition, a transmission material C ′ for transmitting radio waves is disposed in a part of the electromagnetic shield room MS, and radio waves from the radio wave source S outside the electromagnetic shield room MS are connected to the transmission material C ′. The light is transmitted through the slit of the part J into the room.

  In the specific evaluation of the electromagnetic shielding performance of the electromagnetic shielding room MS, a receiving point R is set at an arbitrary position in the room, and the transmitted radio wave W1 transmitted from the radio wave transmission source S is transmitted through the transmission material C ′ and the joint J. Through the slit, the transmitted radio wave W2 is transmitted directly to the reception point R, or as a transmitted radio wave W3 that is indirectly reflected to the reception point R after being reflected by the wall of the room.

  Here, FIG. 4 illustrates the form of six joint portions where slits are easily formed. The joint portion J shown in FIG. 4A is a form in which adjacent conductive materials C and C are overlapped with each other, and the overlapped portion K is spot-fastened with a screw B.

  In the joint portion Ja shown in FIG. 4B, adjacent conductive materials C and C are provided side by side, and a separate conductive material C ″ is disposed so as to straddle them, and the overlapping portion K is spotted by a screw B. It is a fastened form.

  The end portion of the adjacent conductive material C is bent to form a bent portion Ca, both the bent portions Ca and Ca are overlapped, and the overlapping portion K is a bolt B ′. It is a spot-fastened form.

  The joint portion Jc shown in FIG. 4d has one end portion of the adjacent conductive material C bent to the other side to form a bent portion, and this bent portion and the other conductive material C are overlapped, K is a spot spot-fixed with screws B.

  The joint Jd shown in FIG. 4e forms a concave groove M in one end region of the adjacent conductive material C, and the end region including the concave groove M and the end region of the other conductive material C are The overlapped portion K is spot-fastened with a screw B.

  Further, the seam Je shown in FIG. 4f forms the concave grooves M and M having complementary shapes in the end regions of both conductive materials C and C, and the concave grooves M and M of both adjacent conductive materials are formed. Both end regions are overlapped in the positioned posture, and the overlapping portion K is spot-fastened with screws B. In addition to the illustrated example, there are various forms of overlapping of adjacent conductive materials and forms of spot fastening.

  Here, the “transmission attenuation amount of the transmitted radio wave” set in step S2 described above is set based on the following Table 1 specified by the present inventors.

  FIG. 5 is a model diagram showing a virtual image method simulation model in the tracking step S20, and is an embodiment of a simulation model corresponding to the electromagnetic shield room MS shown in FIG.

The transmission material C ′ is set to (x _P1 , y _P1 , z _P1 ), (x _P2 , y _P2 , z _P2 ) at the transmission points P 1 and P 2, and the radio wave transmission source M _S and reception point. Similarly, each three-dimensional position of M _R is set by (x _S , y _S , z _S ), (x _R , y _R , z _R ).

Further, as a method of setting the number of slits and the positions of the joints, for example, six slits SL are set as shown in the figure, and the respective three-dimensional positions are set by (x _SL , y _SL , z _SL ). . In addition, when there are actually 10 slits, all 10 spots may be modeled.

Transmitting radio wave W1, as well is transmitted to the chamber through the transparent point P1, is transmitted to the chamber through the slit SL of the six that are configured as secondary wave source, reaches directly to the receiving point M _R Each ray trajectory of the transmitted radio wave W2, which indirectly arrives after being reflected by the wall surface W2, is traced by a virtual image method simulation.

[Verification result comparing specific value (simulation result) and actual value by specific method of the present invention]
The inventors simulated the electromagnetic shield room shown in FIG. 6a, measured the electromagnetic shield performance, specified the electromagnetic shield performance by the specifying method of the present invention, and compared and verified both the measured values and the specified values. .

The electromagnetic shield room shown in FIG. 6a is an anechoic chamber with each side of 5 m (an electromagnetic wave absorber is attached to each wall surface). One of the walls has a width of 3 m and a height of 2 m. electromagnetic shielding performance measurement opening T _K is provided. Also, installing a slit-shaped connection structure length approximately 2.6 m (slits SL) for the electromagnetic shielding performance measurement opening T _K.

Furthermore, in order to simulate the electromagnetic shield chamber, and paste the conductive material C on the entire surface of the wall facing the opening T _K electromagnetic shielding performance measurement.

  A test radio wave is emitted from the radio wave source S outside the anechoic chamber, and the trace of the transmitted radio wave W2 leaked into the room through the slit SL is transmitted. In the depth direction at a position shifted by 1 m in the horizontal direction from the center), the distribution of the intensity distribution level was measured, and the specific value by the specifying method of the present invention was calculated.

  FIG. 6b shows a plot of the actual measurement value and the specific value on the same graph. In FIG. 6a, the separation distance from the slit is measured in the direction of arrow y from the slit SL.

  From the figure, there is a very high correlation between the measured value and the specified value, and the method for specifying the electromagnetic shielding performance of the present invention precisely specifies the leakage of radio waves from the slit of the joint between the conductive materials. It has been proved that the slit accurately specifies the electromagnetic shielding performance of the electromagnetic shielding chamber, which is appropriately reflected in the components of the electromagnetic shielding chamber.

  The embodiment of the present invention has been described in detail with reference to the drawings. However, the specific configuration is not limited to this embodiment, and there are design changes and the like without departing from the gist of the present invention. They are also included in the present invention.

  C ... conductive material, C '... transparent material, C "... conductive material, R ... receiving point, S ... radio wave source, J, Ja, Jb, Jc, Jd, Je ... joint, MS ... electromagnetic shield room , W1 ... transmitted radio wave, W2 ... transmitted radio wave (direct wave), W3 ... transmitted radio wave (reflected wave), SL ... slit, K ... overlapping location, B ... screw, B '... bolt

Claims (4)

In an electromagnetic shield room in which a plurality of conductive materials are arranged on a wall surface of a building and adjacent conductive materials are connected to each other via a joint portion, the electromagnetic shield of the electromagnetic shield room having at least one joint portion having a slit A method for identifying performance,
The method for specifying the electromagnetic shielding performance includes a setting step for setting various conditions, and a tracking step for calculating the electric field intensity at the receiving point in the electromagnetic shielding room by tracking the radio wave transmitted into the electromagnetic shielding room,
The setting step includes
When the radio wave transmission source outside the electromagnetic shield room is a primary wave source, the slit through which the radio wave transmitted from the primary wave source is transmitted through the slit into the electromagnetic shield room is assumed to be a secondary wave source, and at least the slit Determining the secondary wave source characteristics by setting the number and the three-dimensional position of the wave, setting the directivity and polarization characteristics at the time of incidence of the outgoing radio wave from the primary wave source to the secondary wave source,
The step of determining the transmitted radio wave characteristic by setting the transmission attenuation amount, the directivity characteristic, the polarization characteristic and the phase characteristic of the transmitted radio wave transmitted from the secondary wave source to the electromagnetic shield room,
The tracking step includes
A method of identifying the electromagnetic shielding performance of an electromagnetic shielding room, tracing a trajectory of transmitted radio waves in the electromagnetic shielding room based on a virtual image method and calculating at least an electric field strength at a receiving point in the electromagnetic shielding room.   2. The electromagnetic shield chamber according to claim 1, wherein the joint portion is formed by overlapping adjacent conductive materials, spotting the overlapping portion, and forming the slit at the overlapping portion. A method to identify electromagnetic shielding performance.   The method for specifying the electromagnetic shielding performance of the electromagnetic shielding room according to claim 1 or 2, wherein two or more secondary wave sources are assumed in accordance with two or more slits.   The electromagnetic wave according to any one of claims 1 to 3, wherein the transmitted radio wave reaching the receiving point is composed of a transmitted radio wave that directly reaches from a secondary wave source and a transmitted radio wave that arrives after being reflected by a wall surface in the electromagnetic shield room. A method to identify the electromagnetic shielding performance of a shield room.

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