JP2005109095A - Unwanted radio wave suppressing structure and radio wave absorbing bridge wall - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an unwanted radio wave suppressing structure and a radio wave bridge wall, wherein the load to a base due to a wind load is reduced, to facilitate the provision thereof in a limited space. <P>SOLUTION: In this structure, unwanted radio waves arrived at a radio wave absorbing plate 1, provided with a radio wave absorbing means on a surface on a side of a radio wave arrival direction α can be attenuated and suppressed, and the radio wave absorption plate 1 is installed at a space K along a direction of extending the radio wave absorbing plate 1 within a ground plane to the degree such that a radio wave can be shielded. Thus, a wind is passed between the radio wave absorbing plates 1 without preventing suppression of the unwanted radio wave, and the wind load can be reduced to decrease the load to a base 3. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an unnecessary radio wave suppressing structure and a radio wave absorbing partition wall that suppress unnecessary radio waves flying from the vicinity of a road and improve an electromagnetic wave environment on the road.

  In recent years, automatic toll collection (also referred to as ETC (Electronic Toll Collection)) systems and driving support systems (also referred to as AHS (Advanced Cruise-Assist Highway System)) have been developed on highways. Yes. In these systems, narrow area communication (also referred to as DSRC (Dedicated Short-Range Communication)) in which radio waves are used for communication between a roadside device installed on a road and a vehicle-mounted device mounted on a vehicle is used. It has been. Therefore, with the development of these systems, improvement of the electromagnetic wave environment on the road is demanded.

  Therefore, especially when the automatic toll collection system and the vehicle operation support system are adopted on the road with a large amount of vehicle traffic, the radio wave absorption function such as the radio wave absorption panel with the radio wave absorption function is used to improve the electromagnetic wave environment on the road. It is conceivable to install a fuselage having

  For example, radio wave absorption provided with a radio wave absorber for suppressing unnecessary radio waves generated during radio wave communication or sensing, such as bidirectional communication between a roadside antenna and an onboard unit antenna in an automatic toll collection system A method is shown in which a radio wave absorber, such as a panel, is attached to a road incidental facility, or a main part of the road incidental facility is formed from a radio wave absorber to suppress unnecessary radio waves and solve the above problems. .

JP 2001-217645 A

However, if the radio wave absorption panel as described in Patent Document 1 is installed under a girder, it is in a state like a wall surface when it is installed between lanes, and receives a wind load. In general, the wind load is set to 300 kg / m ^2, and a large load is applied to the foundation on which the radio wave absorption panel is installed. Therefore, an extremely heavy and huge foundation is required.

  The huge foundation itself is expensive in terms of installation cost and effort, but it is limited to the space around existing facilities, for example, between lanes near toll booths where automatic toll collection systems are installed, and driving support roads. It is difficult to install huge foundations in the median strip of the city.

  For example, FIG. 9 is a front view showing an automatic toll collection system having a plurality of lanes. When a vehicle such as a passenger car C, a truck T, a mixer car M, or the like passes, an antenna A is connected to the on-board communication device S. The radio wave R related to the toll collection is emitted from the radio wave R, but the radio wave R is radiated to a certain wide range in order to be surely received by the in-vehicle communication device S. When the radio wave R radiated to other than the in-vehicle communication device S hits the tank M1 of the mixer truck M having a relatively high vehicle height and the upper surface having a metal curved surface, In this way, an unnecessary radio wave R <b> 1 is generated by being reflected almost without being attenuated in the direction or diagonally below. Such unnecessary radio wave R1 is received by the in-vehicle communication device S of the passenger car C traveling in another lane in the same direction, the passenger car C traveling in the lane in the opposite direction, and the truck T, and the toll collection is performed erroneously. Or received by the receiving antenna around the automatic toll collection system, which may cause malfunction of the gate.

  In order to prevent such a problem, the main part of the road incidental equipment near the antenna A is formed of a radio wave absorber, or the radio wave absorber is attached to a site on the radio wave arrival side to attenuate unnecessary radio waves, Transmission can be suppressed and problems caused by unnecessary radio waves can be prevented. The road incidental equipment has a wind load calculated or is not planar and does not receive a wind load, and the wind load is not particularly regarded as a problem in providing a radio wave absorption function.

  However, when installing a partition wall or the like having a radio wave absorption function between the lanes shown in FIG. 9, the space for installation is of course limited, and the space for the foundation that can be installed is already installed. There are many places where it is difficult to install heavy foundations that can bear wind loads because they are subject to extremely strong restrictions by other road-related equipment such as sensors and anti-glare plates.

  Accordingly, the present invention is intended to provide an unnecessary radio wave suppression structure and a radio wave absorption partition wall that can reduce the load on the foundation due to wind load and can be easily provided in a limited space.

  In order to solve the above problems, the present invention has the following configuration. That is, the unnecessary radio wave suppression structure according to the present invention is a structure in which a face plate is installed around a road and unnecessary radio waves flying from the vicinity of the road are suppressed by the face plate. Absorbing means is provided to form a radio wave absorbing plate, and the radio wave absorbing plate is installed at an interval along the direction in which the radio wave absorbing plate extends in the ground plane to such an extent that the radio wave absorbing plate can block radio waves. To do.

  The radio wave absorbing plate is erected in a fish scale shape with the surface on which the radio wave absorbing means is provided facing the direction of radio wave arrival.

  The radio wave absorbing plate is erected by using a support column, and the support column is hidden by radio waves from the arrival direction of the radio wave by the radio wave absorption plate.

  The radio wave absorbing plate is provided between two roads, at least one of which has a communication area.

  The radio wave absorbing plate is characterized in that the return loss with respect to a circularly polarized wave of 5.8 GHz is 20 dB or more in a radio wave incident angle range of 0 degree to 30 degrees.

  The unnecessary radio wave suppressing structure has a shielding effect of 10 dB or more.

  The radio wave is a radio wave related to automatic fee collection.

  The radio wave absorption partition wall according to the present invention is installed on a side edge of a road having a communication area, and suppresses unnecessary radio waves flying from the vicinity of the road by a face plate attached to a support column. A radio wave absorbing means is provided on the surface on the radio wave arrival side to form a radio wave absorbing plate, and the radio wave absorbing plate is installed at intervals along the direction in which the radio wave absorbing plate extends in the ground plane to the extent that the radio wave absorbing plate can block radio waves It is characterized by being.

  The radio wave absorbing partition wall has a shielding effect of 10 dB or more.

  The radio wave absorption partition wall is characterized by being installed in a toll gate and / or around the toll gate using an automatic fee collection system.

  According to the unnecessary radio wave suppression structure according to the first aspect of the present invention, it is possible to attenuate and suppress the unnecessary radio wave that arrives by the radio wave absorbing plate provided with the radio wave absorbing means on the surface on the radio wave arrival direction side. Since the radio wave absorbers are installed at intervals along the direction in which the radio wave absorbers extend in the ground plane to the extent that the radio wave absorbers can block radio waves, the wind wave between the radio wave absorbers does not interfere with the suppression of unwanted radio waves. The load on the foundation can be reduced by reducing the wind load.

  According to the invention of claim 2, since the radio wave absorbing plates are arranged in a fish scale shape, the interval between the radio wave absorbing plates can be increased as compared with the case where they are arranged in parallel, and the wind is smoothly spaced. Is preferable.

  Further, according to the invention of claim 3, the support is often formed from a metal or the like which is a radio wave reflector in order to ensure the strength. It is preferable that the generation of further unnecessary radio waves derived from the above can be prevented in advance.

  Further, according to the invention of claim 4, at least one of the roads can easily be placed in the communication area by appropriately arranging the radio wave absorbers or providing radio wave absorbers on both sides of the face plate without taking measures against unnecessary radio waves on each road. It is possible to suppress unnecessary radio waves on two roads having the above, and the effect of applying the unnecessary radio wave suppression structure is extremely high, which is preferable.

  According to the invention of claim 5, in the automatic toll collection system, it is possible to effectively attenuate unnecessary radio waves by the high radio wave absorption performance of the radio wave absorbing plate to prevent harmful effects due to unnecessary radio waves, and to improve the effect of installation. .

  According to the invention of claim 6, in the communication area, the intensity of the radio wave is set sufficiently higher than the lower limit of the response sensitivity of the vehicle-mounted device so that the vehicle-mounted device can reliably receive information. The intensity when unnecessary radio waves generated by the reflection of strong radio waves are received by the OBE is about 10 dB higher than the lower limit of the response sensitivity of the OBE, and the lower limit of the response sensitivity of the OBE is reduced by the unnecessary radio wave suppression structure. If a shielding effect equivalent to or higher than the excess power level can be obtained, it is preferable that there is almost no possibility of causing trouble even if unnecessary radio waves reach the adjacent lane.

  Further, according to the invention of claim 7, it is preferable that the foundation can be made small, so that it can be suitably applied to an automatic toll collection system with little space around the communication area, and the effect to be applied can be further enhanced.

  According to the radio wave absorption partition wall of the present invention as set forth in claim 8, the radio wave absorption plate is installed at intervals along the direction in which the radio wave absorption plate extends in the ground plane to such an extent that the radio wave absorption plate can block the radio wave. This makes it possible to allow wind to pass between the wave absorbers without hindering suppression of unwanted radio waves, reduce wind load and reduce the addition to the foundation, making it difficult to secure the space for the foundation It can be installed at a place.

  According to the invention of claim 9, in the communication area, the intensity of the radio wave is set sufficiently higher than the lower limit of the response sensitivity of the vehicle-mounted device so that the vehicle-mounted device can reliably receive information. The intensity when unwanted radio waves generated by the reflection of strong radio waves are received by the vehicle-mounted device is about 10 dB higher than the lower limit of the response sensitivity of the vehicle-mounted device. If a shielding effect equivalent to or higher than the excess power level can be obtained, it is preferable that there is almost no possibility of causing trouble even if unnecessary radio waves reach the adjacent lane.

  According to the invention of claim 10, in an automatic toll collection system in which installation space is extremely limited by an antenna, a sensor, etc., the advantage of applying a radio wave absorbing partition wall that requires a small space for the foundation is extremely large. preferable.

BEST MODE FOR CARRYING OUT THE INVENTION The best embodiment according to the present invention will be specifically described below with reference to the drawings.
FIG. 1 is an explanatory view showing an unnecessary radio wave suppressing structure and a radio wave absorbing partition wall according to the present invention. The radio wave absorbing partition wall 10 is provided on the side edge of the lane L1 having the communication area by the antenna A provided in the gate related to the toll collection of the automatic toll collection system (ETC), and is erected from the foundation 3 A radio wave absorbing plate 1 is attached to the support 2 via a trunk edge 4. The radio wave reflectors 1 are erected in two rows so that the intervals K are staggered along the direction in which the lane L1 extends.

  2 is a plan view from above showing a state in which the electromagnetic wave absorption partition wall shown in FIG. 1 is installed between lanes. B) When one lane has a communication area, b) When both lanes communicate The case of having a region is shown. The lane L1 side of the radio wave absorption partition wall 10 where the antenna A is disposed and has a communication area is the radio wave arrival direction α, but the radio wave absorption plate 1 is disposed on the radio wave arrival direction α side of the support column 2, The support column 2 is concealed by radio waves from the arrival direction of radio waves by the radio wave absorbing plate 1. Further, since the gaps K provided between the radio wave absorbers 1 are alternately arranged for the radio wave absorbers 1 arranged in two rows, the wind can pass through the gaps K and the wind load can be reduced. The radio wave is prevented from reaching an adjacent lane, and the interval K provided in the radio wave absorbing plate 1 does not prevent the radio wave from being shielded.

  Next, in (b), the lanes L1 and L2 are each provided with an antenna A and have a communication area. May come. By attaching the radio wave absorber 1 to each of the radio wave arrival directions α and β of the support 2, the unnecessary radio wave R1 arriving from both sides of the radio wave arrival directions α and β is prevented from reaching the adjacent lane, and the distance K It is possible to conceal the column 2 from the unnecessary radio wave R1 that has passed through the radio wave, and to prevent generation of a new unnecessary radio wave due to the reflection of the column 2.

  Due to the radio wave absorption partition wall using such an unnecessary radio wave suppression structure, for example, a mixer car M, which is one of the vehicle types most likely to generate an unnecessary radio wave due to reflection, travels in a lane L1 having a communication area. Even when the radiated radio wave R related to the toll collection is reflected by the cylindrical metal tank M1 to generate the unnecessary radio wave R1, it is attenuated by the radio wave reflector 1 even when it travels to the parallel lane L2 side with little attenuation. In addition, there is no risk of reaching the vehicle-mounted device S mounted on the passenger car C traveling in the parallel lane L2 while maintaining the strength with which the vehicle-mounted device S responds, and it is possible to prevent the occurrence of excessive charge collection or malfunction. it can.

  Regarding the shielding effect of the unnecessary radio wave suppression structure and the radio wave absorption partition wall plate, for example, in the first communication area in the automatic toll collection system in Japan, the radio wave R transmitted from the transmission antenna A has a power level of −50.5 dBm or more. Need to be received by the vehicle-mounted device S. In the non-response region, it is necessary to have a power level of -70.5 dBm or less. In order to form such a communication area, the maximum value of received power in the first communication area can be about −45 to −40 dBm. The polarized wave of the radio wave R transmitted from the transmitting antenna A and reaching the vehicle-mounted device S without being reflected in the middle is a right-handed circularly polarized wave, and the polarized wave of the unnecessary radio wave R1 reflected by the mixer truck M or the like. Is a left-handed circularly polarized wave. Here, when the vehicle-mounted device S receives a left-handed circularly polarized wave, it is assumed that the received signal is received by about 20 dB lower than when a right-handed circularly polarized wave is received. The unnecessary radio wave R1 reflected by the mixer truck M or the like is received by the vehicle-mounted device S at a power level of −65 to −60 dBm. Since this electric power level is higher than -70.5 dBm, the onboard equipment S will respond. Therefore, the shielding effect required when the radio wave absorbing partition wall 10 or the like is installed is at least about 10 dB, preferably about 5 dB is expected, more than 15 dB, more preferably about 10 dB is expected, It is 20 dB or more. Here, since the unnecessary radio wave R1 can reach the vehicle-mounted device S with the same propagation distance as the radio wave R, attenuation due to the radio wave propagation distance is not considered.

  Furthermore, the shielding effect of the radio wave absorbing plate alone needs to be more than the shielding effect of the unnecessary radio wave suppressing structure and the radio wave absorbing partition wall plate, and is preferably about 5 to 10 dB larger than the shielding effect of the unnecessary radio wave suppressing structure. Furthermore, “a degree to which radio waves can be shielded” in this specification includes a meaning “to a degree capable of realizing a desired shielding effect”.

  FIG. 3 is a cross-sectional view showing a cross section of the radio wave absorber 1. The radio wave absorbing plate 1 is provided with radio wave absorbing means 11 on the radio wave arrival direction α side of the face material 12, and the radio waves incident by the radio wave absorbing means 11 are attenuated when reflected, thereby suppressing unnecessary radio waves. The radio wave absorbing means 11 is arranged in order from the radio wave arrival direction α side with the radio wave absorption layer and the reflection layer, and the input impedance that anticipates the radio wave traveling direction from the surface of the radio wave arrival direction α side is incident according to the characteristic impedance of free space It attenuates the radio waves that are transmitted. The radio wave absorption layer uses at least one of conductive radio wave absorption materials such as carbon black, carbon graphite and metal powder, and magnetic radio wave absorption materials such as ferrite, and these radio wave absorption materials are made of synthetic resin or synthetic resin. It is formed by mixing in a dielectric such as foam or rubber, or by mixing in a paint and applying. Moreover, you may use a sintered magnetic body as a radio wave absorption layer.

  Furthermore, a resistive layer, a spacer, and a reflective layer are arranged in this order from the radio wave arrival direction α side, and the thickness of the spacer is set to about ¼ of the wavelength of the radio wave inside the spacer, so that the resistance layer has a radio wave arrival direction α side. The input impedance in which the radio wave traveling direction is expected from the surface may be attenuated in accordance with the characteristic impedance of free space. Furthermore, the radio wave absorption layer may be a laminated body in which a plurality of layers and resistance layers having different electrical characteristics (complex relative permittivity and complex relative permeability) are stacked. The radio wave absorption layer may include a protective layer that protects a layer containing a radio wave absorption material, a resistance layer, and the like, and the protective layer may be disposed on the outermost surface on the radio wave arrival direction α side. The reflective layer may also serve as the face material 12 using a metal plate.

  The radio wave absorbing plate 1 is formed by arranging these on the face material 12 by sticking them or the like and also serving as the face plate 12. Further, all the layers constituting the radio wave absorption layer and the reflection layer are made of a transparent or light transmissive material, so that the radio wave absorbing means 11 is made transparent, and the face material 12 is also transparent or a light transmissive material. Therefore, the radio wave absorber 1 may be transparent. For example, the radio wave absorbing plate 1 may be configured such that a protective layer, a resistance layer, a spacer, a reflective layer, and a face material 12 are sequentially arranged from the radio wave arrival direction α side, and all of these are made of a transparent or light transmissive material. Here, the face material 12 is made of a synthetic resin plate, a synthetic resin sheet, or the like, and may have a function of protecting the reflective layer.

  FIG. 4 is an explanatory view showing another embodiment of the unnecessary radio wave suppressing structure according to the present invention. As in FIG. 1, unnecessary radio waves derived from radio waves from the antenna A in the automatic toll collection system are suppressed, but the support column 2 erected on the foundation 3 is connected via a connecting means 4 which is a trunk edge. The radio wave absorbing plate 1 is attached with the surface on which the radio wave absorbing means 11 is provided at an angle upward. The antenna A is arranged above, and unnecessary radio waves reflected from the mixer truck M and the like also fly from above, and the unnecessary radio waves are more reliably suppressed by setting the angle θ as described above. can do. In addition, the radio wave absorbing plate 1 attached with an upward angle θ may be divided into a plurality of stages in the vertical direction. In this case, the depth of the radio wave absorbing partition wall 10 is larger than that shown in FIG. D can be reduced and the wind pressure reduction effect can be further enhanced.

  FIG. 5 is a plan view from above showing still another embodiment of the unwanted radio wave suppressing structure according to the present invention. This figure shows the suppression of unnecessary radio waves in the automatic toll collection system, similar to that shown in FIGS. 1 to 4, but in (a), a radio wave absorbing plate is placed on the column 2 erected on the foundation 3. 1, a radio wave absorbing partition wall 10 is formed by attaching the surface on which the radio wave absorbing means 11 is provided toward the lane L1 side having a communication area, and the radio wave absorbing plates 1 are spaced apart from each other by a distance K. It is arranged like a fish scale in the ground plane. B) arranges the radio wave absorbing plate 1 in a fish scale shape on the ground plane with the surface on which the radio wave absorbing means 11 is provided between the lanes L1 and L2 having the communication area facing the respective lanes L1 and L2. Thus, a radio wave absorbing partition wall 10 is formed. Such a fish scale-like arrangement of the radio wave absorbing plates 1 increases the range in which shielding is possible even if unnecessary radio waves are incident at an angle that is relatively perpendicular to the radio wave absorbing partition wall 10. K can be widened, and even when the radio wave absorbing plate 1 is hit by the wind, the wind can smoothly flow along the outer surface of the radio wave absorbing plate 1 and the effect of reducing the wind pressure can be enhanced.

  Further, the antenna A is arranged at the upper side, and unnecessary radio waves generated by being reflected by the mixer truck M or the like also fly from the upper side. By setting the angle as described above, the unnecessary radio waves can be more reliably transmitted. Can be suppressed. In addition, the radio wave absorbing plate 1 attached at an upward angle may be divided into a plurality of stages in the vertical direction, and in this case, the depth of the radio wave absorbing partition wall 10 can be made smaller than when not divided, Furthermore, the wind pressure reduction effect can be enhanced.

  In addition, unnecessary radio waves can be suppressed by arranging the radio wave absorber 1 as shown in FIG. In (b), the radio wave absorbing plate 1 is configured such that the ends of the radio wave absorbing plate 1 are located from the side of the radio wave arrival direction α in the intermediate column 2 except for the end of the column 2 erected on the foundation 3. The radio wave absorber 1 is attached in an oblique direction from the front and back so as to overlap each other, and the radio wave absorber 1 is arranged in a sawtooth shape. With the arrangement of the radio wave absorbing plate 1, the flow of wind can be made smooth as in the case of the fish scale arrangement, and the number of upright columns 2 can be reduced, and the radio wave can be reliably shielded with a simple structure. Is possible.

  In (b), the radio wave absorbing partition wall 10 is provided between two lanes L1 and L2 having a communication area, and the radio wave absorbing plates 1A and 1B are spaced apart from each other by lanes L1 and L2. In the sawtooth shape, the radio wave absorbing plate 1B on the lane L2 side closes the gap K1 provided between the radio wave absorbing plates 1A on the lane L1 side when viewed from the radio wave arrival directions α and β. Similarly, the gap K2 provided between the radio wave absorbing plates 1B on the lane L2 side is also closed by the radio wave absorbing plate 1A on the lane L1 side, so that even if the gaps K1 and K2 are large, the tank of the mixer M The unnecessary radio wave R1 generated by the reflection by M1 is shielded reliably. The radio wave absorbing plates 1A and 1B may be provided with the radio wave absorbing means 11 only on the side directed to the respective lanes L1 and L2. However, by providing the radio wave absorbing means on both sides of the face material 12, it is possible to suppress unnecessary radio waves. Can be more certain.

  Furthermore, the antenna A is arranged at the upper side, and unnecessary radio waves generated by being reflected by the mixer truck M or the like also fly from the upper side. It can be surely suppressed.

  FIG. 7 shows a modification of the radio wave absorbing wall 10 in which the radio wave absorbing plate 1 shown in FIG. In this modification, the surface of the radio wave absorbing plate 1 on which the radio wave absorbing means 11 is provided is not only arranged in a fish scale shape on the ground plane so as to face the radio wave arrival direction α or β, but also by the connecting means 4. The radio wave absorber 1 is attached with an upward angle θ. In addition, as shown in the figure, the radio wave absorber 1 attached with an upward angle θ may be divided into a plurality of stages in the vertical direction. The depth D can be reduced, and the wind pressure reduction effect can be further enhanced by providing an interval in the vertical direction. Although a part of the radio wave absorbing wall 10 is shown in this figure, a plurality of radio wave absorbing plates 1 can be extended in the ground plane as shown in FIG.

  The overlap of the radio wave absorbers 1 arranged in two rows will be described with reference to FIG. It is preferable to provide an overlap of the radio wave absorber 1 with respect to the path of the unnecessary radio wave R1 so that a gap between the radio wave absorbers 1 is not generated with respect to the assumed unnecessary radio wave R1. If the width of the overlap V is equal to or greater than the wavelength of the radio wave to be shielded, it is preferable that shielding is performed including the diffracted radio wave, and if the width is 3 wavelengths or greater, the shielding is further ensured. Further, not only the overlap V in the direction along the direction in which the radio wave absorber is extended in the ground plane, but also the overlap of the radio wave absorber 1 generated when the radio wave absorber 1 is divided into a plurality of stages in the vertical direction. It is preferable to provide a similar overlap V.

It is explanatory drawing which shows one Embodiment of the unnecessary electromagnetic wave suppression structure concerning this invention. It is a top view from the upper part of the unnecessary electromagnetic wave suppression structure shown in FIG. It is sectional drawing which shows the detail of the electromagnetic wave absorber used for the unnecessary electromagnetic wave suppression structure concerning this invention. It is explanatory drawing which shows other embodiment of the unnecessary electromagnetic wave suppression structure concerning this invention. It is a top view from the upper side which shows other embodiment of the unnecessary electromagnetic wave suppression structure concerning this invention. It is a top view from the upper side which shows other embodiment of the unnecessary electromagnetic wave suppression structure concerning this invention. It is a perspective view which shows other embodiment of the unnecessary electromagnetic wave suppression structure concerning this invention. It is a top view explaining the overlap of a radio wave absorber. It is explanatory drawing which shows the state of generation | occurrence | production of the unnecessary electric wave in the automatic fee collection system periphery.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Radio wave absorption board 11 Radio wave absorption means 2 Support | pillar 3 Foundation 10 Radio wave absorption partition wall K Interval

Claims (10)

A face plate is installed around the road, and unnecessary radio waves flying from the vicinity of the road are suppressed by the face plate, and the face plate is provided with a radio wave absorbing means on at least a radio wave arrival side surface to be a radio wave absorbing plate. An unnecessary radio wave suppression structure, characterized in that the radio wave absorbing plate is installed at an interval along a direction in which the radio wave absorbing plate extends in a ground plane to such an extent that the radio wave absorbing plate can block radio waves. 2. The radio wave absorbing plate is erected and arranged in a fish scale shape with a surface on which a radio wave absorbing means is provided at least in a direction within a horizontal plane, generally facing a radio wave arrival direction. Unnecessary radio wave suppression structure described in 1. The unnecessary radio wave suppression structure according to claim 1 or 2, wherein the radio wave absorbing plate is erected using a support, and the support is hidden from the radio wave arrival direction by the radio wave absorbing plate. The unnecessary radio wave suppressing structure according to claim 1, wherein at least one of the radio wave absorbing plates is provided between two roads having a communication area. 5. The electromagnetic wave absorbing plate according to claim 1, wherein a reflection attenuation amount with respect to a circularly polarized wave of 5.8 GHz is 20 dB or more in a radio wave incident angle range of 0 degree to 30 degrees. Unnecessary radio wave suppression structure. 6. The unnecessary radio wave suppressing structure according to claim 1, wherein the unnecessary radio wave suppressing structure has a shielding effect of 10 dB or more. The unnecessary radio wave suppression structure according to claim 1, wherein the radio wave is a radio wave related to automatic fee collection. It is installed on the side edge of a road having a communication area, and suppresses unnecessary radio waves coming from the vicinity of the road by a face plate attached to a support, and the face plate is provided with radio wave absorbing means at least on the surface on the radio wave arrival side. A radio wave absorbing plate, and the radio wave separating plate is installed at intervals along a direction in which the radio wave absorbing plate extends in the ground plane to such an extent that the radio wave separating plate can block radio waves. wall. 9. The radio wave absorbing partition wall according to claim 8, which has a shielding effect of 10 dB or more. 10. The radio wave absorption partition wall according to claim 8 or 9, wherein the radio wave absorption partition wall is installed in a toll booth using an automatic toll collection system and / or around a toll booth.

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