JP2016082071A - Method of manufacturing wave absorber and second wave absorber for use in this method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of manufacturing a wave absorber which allows for adjustment of the characteristics when building an anechoic chamber anew, or at the time of additional adjustment of anechoic chamber, and to provide the wave absorber.SOLUTION: To satisfy the NSA characteristics (30M-1GHz) and the SVSWR characteristics (1-18GHz) by inserting a wave absorber (second wave absorber), consisting of a matching shape and a disposition shape, or their combination shape, or a shape including them, into the valley of a wave absorber (first wave absorber), thereby adjusting the amount of a dielectric loss film existing in a certain space and the frequency characteristics of wave absorption.SELECTED DRAWING: Figure 1

Description

The present invention relates to a technique of a radio wave absorber that absorbs electromagnetic waves, and in particular, can be additionally arranged in a valley portion of a radio wave absorber having a shape such as a cone, a frustum, a wedge shape, or a cross girder. The present invention relates to a technique of a matching electromagnetic wave absorber.

Conventionally, in an anechoic chamber such as an anechoic chamber or a semi-anechoic chamber, a method of installing a matching radio wave absorber on the front surface of a sintered ferrite type radio wave absorber has been adopted for the purpose of improving its characteristics. It became so.

Such a conventional wave absorber for matching is made of a material in which carbon or the like is uniformly dispersed in a synthetic resin such as foamed urethane, foamed ethylene, or foamed styrene, such as a cone, a truncated cone, a wedge shape, or a cross-beam type. It is formed into a shape. Further, in order to reduce the weight and reduce the transportation cost, a radio wave absorber having a hollow structure configured by combining plate-like dielectric loss films has been put into practical use.

  In particular, in a 3 m, 5 m method anechoic chamber in which a radio wave absorber is used, NSA characteristics (radio wave absorption performance at 30 MHz to 1 GHz) are conventionally required, but SVSWR characteristics (radio wave absorption performance at 1 GHz to 18 GHz) are not required. As an indispensable characteristic in the standards of the Voluntary Control Council for Radio Interferences (abbreviated as the VCCI Association) such as information processing equipment, which was created with reference to the international standards of the International Standards for International Radio Interference (CISPR) since 2011 It is requested. The performance of the anechoic chamber used for the measurement of conducted and radiated disturbances stipulated in these regulations is greatly affected by the performance of the electromagnetic wave absorber attached to the inside of the anechoic chamber, and characteristics adjustment is necessary to obtain good results with the SVSWR characteristics. is necessary. In particular, if the height of the matching absorber is about 1 m, it is easy to realize. However, in a small anechoic chamber, a smaller radio wave absorber is required to widen the measurement space. In the case of a hollow structure using a dielectric loss film, the amount of dielectric loss existing in a fixed space in front of the ferrite tile can be fine-tuned using the volume, area, or composition. There is a problem that it is difficult only with the shape (see Patent Document 1).

Specifically, for example, as a technique for improving the frequency characteristics of the original wave absorber in a wide band, it is good by using a wave absorber having a shape that combines not only a large cone but also a small cone from the beginning. There is an invention relating to a structure having special characteristics (see Patent Document 2). In this example, “a first radio wave introduction portion configured by arranging a plurality of quadrangular pyramidal projections made of a dielectric loss material, and provided between each projection portion of the first radio wave introduction portion, By providing the second radio wave introduction portion made of a dielectric loss material having a wedge shape or a quadrangular pyramid shape in the direction of arrival of radio waves, favorable characteristics are obtained.

Further, “a surface member having at least one of a cone shape, a pyramid shape, a wedge shape in which the apex or the tip portion of the radio wave absorber is opposed to the direction of radio wave flight, and made of a non-conductive material; A wave absorber formed by filling a powder containing a soft magnetic material into the gap, and a ferrite sintered tile on the side of the back member of the radio wave absorber. A composite wave absorber comprising a dielectric loss body disposed to fill a cavity between the back member and the sintered ferrite tile. A structure called “absorber” has also been proposed (see Patent Document 3).

The present invention pays attention to these prior arts, and the inventors have not only good electromagnetic wave absorption characteristics and new construction of an anechoic chamber, but also improved performance by additional adjustment to the anechoic chamber, and modification of existing anechoic chambers, etc. When building an environment where electromagnetic waves are suppressed in consideration of the demands of the above, it is possible to suppress the increase in cost by arranging additional electromagnetic wave absorbers, near the wall facing the evaluation object, indoor corners, or entrances and exits Regardless of the presence or absence of a structure that changes the configuration of the anechoic chamber surface such as the inspection port, measurement terminal introduction part, air conditioning vent, etc., adjust the part where the electromagnetic wave absorption characteristics change or the part with large reflection, The present invention has led to the provision of a radio wave absorber manufacturing method and radio wave absorber capable of improving performance.

JP 2004-103790 A JP-A-8-274491 JP2011-91273A

In the electromagnetic wave absorber installed on the wall surface such as an anechoic chamber, the electromagnetic wave absorber manufactured with industrially standardized dimensions (for example, the bottom area is 60 cm in length for the convenience of manufacturing and mounting the pyramid type electromagnetic wave absorber) * In the case of 60 cm in width, the number of pyramid shapes is generally two or three in length and width.) If left as it is, there is a limit to the ability to absorb radio waves due to dielectric loss. In order to provide good characteristics in a wide frequency band, it is difficult to make adjustments in manufacturing and construction, and in order to improve existing equipment, it is necessary to replace the wave absorber in the anechoic chamber. There was a problem of becoming.

The present invention is a method of manufacturing a radio wave absorber, a molding step for obtaining a second radio wave absorber comprising a matching shape and an arrangement shape, or a combination thereof, or a shape including these, and the molding step And a mounting step for adding the second electromagnetic wave absorber obtained by the above to the existing first electromagnetic wave absorber, and a method of manufacturing the electromagnetic wave absorber that improves the electromagnetic wave absorption characteristics through the two steps It is about. By using such a manufacturing method, a manufacturing method for selecting the shape and material of the second wave absorber disposed in the first wave absorber is particularly desirable. In addition to the manufacturing method for performing the above, a manufacturing method for improving the SVSWR characteristics can be selected. At this time, as a method of attaching the second radio wave absorber to the first radio wave absorber, the second radio wave absorber can be attached to the existing structure by taking measures such as adhesion, clamping, engagement, and screwing. It is desirable that the absorber is secured so as not to drop off or be displaced even if it is installed on the ceiling, wall surface, or bottom surface.

In the method for manufacturing a radio wave absorber, the addition of the second radio wave absorber to the first radio wave absorber is intended to increase the total amount of the radio wave absorber. It relates to a manufacturing method. In particular, in the second wave absorber manufacturing method, the matching shape of the second wave absorber is the same or similar to that of the first wave absorber, and the material is selected to improve the wave absorption characteristics by increasing the total amount. A manufacturing method can also be selected.

Further, in the method for manufacturing the radio wave absorber, the addition of the second radio wave absorber to the first radio wave absorber is intended to improve radio wave absorption characteristics in a desired frequency region. A method of manufacturing the radio wave absorber. In particular, in the second radio wave absorber manufacturing method, the matching shape of the second radio wave absorber is improved in radio wave absorption characteristics in a frequency band (for example, NSA characteristic or SVSWR characteristic) that is insufficient only by the first radio wave absorber. A manufacturing method can also be selected that selects suitable shapes and materials.

  Further, the second wave absorber of the present invention is a second wave absorber used in addition to the first wave absorber, and the overall shape thereof is composed of a matching shape and an arrangement shape or a combination shape thereof, The matching shape is a shape composed of any one of a cone, a frustum, a wedge shape, a cross-girder shape that exhibits radio wave absorption characteristics, or a combination thereof, and the arrangement shape is the first shape A second electromagnetic wave absorber having a shape necessary for arranging and fixing the second electromagnetic wave absorber in contact with a valley portion of the electromagnetic wave absorber. By using such a radio wave absorber, it can be fixed to the first radio wave absorber by bonding, narrowing, engaging, screwing, etc. In addition, it is possible to achieve better radio wave absorption characteristics in addition to the absorption effect of the material to be used.

Further, the present invention may be the second radio wave absorber, wherein the second radio wave absorber is characterized in that the inside thereof has a hollow structure. By using such a radio wave absorber, it is possible to easily install the first radio wave absorber with a lighter weight. In addition, a part of the structure may be solid after installation or the like. For example, filling a foam with absorption characteristics.

Further, the present invention may be the second radio wave absorber, wherein the second radio wave absorber is a solid structure. By using such a radio wave absorber, it is possible to obtain a radio wave absorber having more excellent radio wave absorption characteristics. It is also effective to make a part of the solid structure into a hollow structure. For example, it is possible to reduce the weight within a range that does not affect the characteristics.

  The present invention may be the second radio wave absorber, wherein the second radio wave absorber can be formed by bending a thin plate member. By using such a radio wave absorber, the matching shape and the arrangement shape can be easily made by bending, and at the time of construction such as an anechoic chamber, it is excellent in portability without being restricted by the dimensions of the material carry-in port, You may comprise a bending structure so that a thin plate member may be arrange | positioned inside so that rigidity may be increased.

Further, in the second wave absorber, the entire shape is manufactured with a hollow structure, and then a foamable material or a liquid with dielectric loss is fed into the interior to be cured, or a powder is fed in, or those A second radio wave absorber characterized in that a solid structure is produced by a combination of the above. By using such a radio wave absorber, the structure may be such that the hollow site is increased and the weight is reduced, while the solid site is responsible for radio wave absorption.

Further, the second wave absorber, the material having radio wave absorption performance, can be obtained by mixing or coating carbon fiber or a material having a large dielectric loss so that the concentration distribution is uniform or has a gradient in the concentration distribution. The manufactured second wave absorber may have good radio wave absorption performance in a frequency range of 30 MHz to 26.5 GHz or less. Such a radio wave absorber may be mixed with carbon fiber from the beginning to increase the radio wave absorption amount, or may be improved in radio wave absorption characteristics by applying a material having a high dielectric loss regardless of before and after construction.

The method of manufacturing a radio wave absorber using the second radio wave absorber according to the invention of the present application in addition to the first radio wave absorber is a method for adjusting characteristics during construction of an anechoic chamber. Or add it only to the part where the electromagnetic wave absorption characteristics change or the part where reflection is large, such as the structure where the configuration of the anechoic room interior such as the entrance / exit, inspection port, measurement terminal introduction part, air conditioning vent, etc. changes. Since it is used, it is possible to construct only necessary parts. Therefore, the present invention provides a radio wave absorber manufacturing method and a radio wave absorber that can improve performance not only when a new anechoic chamber is newly constructed, but also by additional adjustment to an existing anechoic chamber. At this time, in order to improve the electromagnetic wave absorption characteristics of the anechoic chamber, for example, the performance of the entire anechoic chamber can be improved by providing characteristics specific to the electromagnetic wave absorption characteristics corresponding to the SVSWR characteristics in addition to the NSA characteristics. This is an excellent effect. Further, at this time, as a method of attaching the second radio wave absorber to the first radio wave absorber, the first structure can be obtained by performing treatment such as adhesion, clamping, engagement, and screwing on the existing structure. Even if the two electromagnetic wave absorbers are easily installed on the ceiling, wall surface, or bottom surface, they can be locked so as not to drop off or be displaced.

In addition, according to the method for manufacturing a radio wave absorber using the second radio wave absorber according to the present invention in addition to the first radio wave absorber, the radio wave absorber is increased by increasing the total amount of the radio wave absorber having radio wave absorption characteristics. The excellent effect of increasing the amount and improving the radio wave absorption characteristics is exhibited.

In addition, according to the method of manufacturing a radio wave absorber that uses the second radio wave absorber according to the present invention in addition to the first radio wave absorber, for example, when it is desired to improve the NSA characteristics of the first radio wave absorber to be added, When the SVSWR characteristics are desired to be satisfied, an excellent effect that the shape / dimension according to the target frequency band can be used is exhibited.

In addition, the second wave absorber according to the present invention has a matching shape and an arrangement shape or a combination thereof, and when the matching shape has the same shape as the first wave absorber, the first wave absorber It has the effect of changing the total amount of electromagnetic wave absorption based on the frequency, and when selecting a shape, size, and material different from the first electromagnetic wave absorber, improve the frequency characteristics and directionality of the electromagnetic wave absorption characteristics. It exhibits an excellent effect that it can be adjusted to a characteristic specific to the above.

Further, in the second radio wave absorber according to the present invention, by using a matching shape and an arrangement shape or a combination shape thereof, the matching shape is a cone, a frustum, a wedge shape, or a cross-girder type that exhibits radio wave absorption characteristics. In addition to providing a shape composed of any one of these, or a combination thereof, the arrangement shape has an arrangement relationship with the first radio wave absorber, and in addition, as a radio wave absorber that the arrangement shape itself has It exhibits an excellent effect of exhibiting the function of.

Further, in the second radio wave absorber according to the present invention, when a radio wave absorber characterized by having a hollow structure is used, the radio wave absorber is disposed on the first radio wave absorber and installed on a ceiling, a wall surface or the like. Even in this case, since it is lightweight, it exhibits an excellent effect that it is easy to add by relatively easy adhesion.

Further, in the second radio wave absorber according to the present invention, when the radio wave absorber characterized in that the internal structure is a solid structure, the radio wave is more excellent due to the internal radio wave absorption effect than the hollow structure. Absorption characteristics can be imparted. For example, by placing a part of the hollow part in the alignment shape part and a part of the solid part in the arrangement shape part, the weight of the solid part that adds absorption characteristics is reduced and the arrangement shape is directly supported by the arrangement shape. Therefore, it exhibits excellent effects in terms of performance and construction. Note that the solid structure portion may be filled with resin or may be formed of a powdery material that causes high dielectric loss.

Further, in the second radio wave absorber according to the present invention, the second radio wave absorber that can be formed by bending the thin plate member by the manufacturing method can be easily made by bending the matching shape and the arrangement shape. it can. Thereby, the effect excellent in portability is exhibited. Note that an adhesive portion corresponding to a margin necessary for fixing the bent structure may also be used as a structure for absorbing radio waves.

Further, in the second wave absorber according to the present invention, the radio wave absorber having a solid structure by filling the hollow portion with a material having dielectric loss after the hollow wave absorber is manufactured, It is easy to carry in, and after that, by filling it, it exhibits an excellent effect that it can be corrected after installing the radio wave absorption characteristics.

Further, in the second radio wave absorber according to the present invention, carbon material fibers, powders, or magnetic materials that absorb radio waves by magnetic loss, such as iron, nickel, ferrite, or these In addition to the method of mixing and molding the high-functional material combined with the above, the thin-plate structure portion is obtained by impregnating or applying the high-functional material in the subsequent step to the thin-plate structure portion of the second radio wave absorber previously molded. The radio wave absorption performance may be improved. The solid part of the second radio wave absorber is solidified by injecting a high-functional material into a cotton-like state such as powder, foam, glass wool, or by injection. You may improve the electromagnetic wave absorption characteristic of the solid structure part of a 2nd electromagnetic wave absorber by shape | molding in a state. Using these effects of improving the radio wave absorption characteristics, an excellent effect of having good radio wave absorption characteristics particularly in a frequency band of 30 MHz to 26.5 GHz is exhibited. In particular, among the NSA characteristics (30 MHz to 1 GHz) and SVSWR characteristics (1 GHz to 18 GHz) required for 3 m and 5 m anechoic chambers, the NSA characteristics are satisfied by the base first electromagnetic wave absorber, and the SVSWR characteristics need to be modified. By attaching the second electromagnetic wave absorber to a specific part, it becomes easy to achieve the conditions of the NSA characteristic and the SVSWR characteristic. Moreover, since the 2nd electromagnetic wave absorber to add should just be attached only to a required site | part, the expense required for the characteristic improvement of an electromagnetic wave anechoic chamber can be held down cheaply.

It is a whole schematic explanatory drawing of the electromagnetic wave absorber which concerns on this invention. It is a block diagram which shows arrangement | positioning of the various electromagnetic wave absorber which concerns on this invention. It is a side view which shows the relationship between the 1st and 2nd electromagnetic wave absorber which concerns on this invention. It is a perspective view of the alignment shape of the 1st and 2nd electromagnetic wave absorber which concerns on this invention. It is a schematic diagram which shows the cross-section of the 2nd electromagnetic wave absorber which concerns on this invention. It is explanatory drawing which shows the effect of the 2nd electromagnetic wave absorber which concerns on this invention.

The present invention is obtained by a molding process for obtaining the second radio wave absorber 1 having the matching shape (S) and the arrangement shape (H), or a combination thereof, or a shape including these, and the molding process. And a mounting step for adding the second radio wave absorber 1 to the existing first radio wave absorber 2, and the greatest feature is that the radio wave absorption characteristics are improved through the two steps. . Hereinafter, description will be given based on the drawings. However, the following drawings are only examples, and these shapes, dimensions, and forms may be changed in the technical scope of the present invention.

FIG. 1 is an overall schematic explanatory view of a radio wave absorber 100 according to the present invention. Some hidden lines are omitted.
FIG. 1A is a perspective view of the second radio wave absorber 1. The second electromagnetic wave absorber 1 in FIG. 1A is mainly composed of a matching shape (S) indicated by a hatched portion surrounded by a thick line, and an arrangement shape (H) indicated by an unhatched portion. Is done. However, the matching shape (S) and the arrangement shape (H) are provided so that the portion corresponding to the role of the first electromagnetic wave absorber 2 is additionally used as the matching shape (S) and the feature of the present invention. The provided arrangement shape (H) is divided for convenience. Therefore, the effect of absorbing the radio wave generated by the dielectric loss of the second radio wave absorber 1 has a special intentional difference in dielectric loss, and the second radio wave absorber 1 as a whole is not fixed by a metal material. It is what you have. Next, FIG. 1B is a perspective view showing a state in which the first radio wave absorber 2 is installed on the ferrite radio wave absorber 3. FIG.1 (c) is a perspective view which shows the state which has arrange | positioned the 2nd electromagnetic wave absorber 1 of Fig.1 (a) to the 1st electromagnetic wave absorber 2 of FIG.1 (b).

  FIG. 2 is an arrangement view showing the arrangement of the second radio wave absorber 1, the first radio wave absorber 2, and the ferrite radio wave absorber 3 constituting the radio wave absorber 100 according to the present invention. In FIG. 2, the alignment shape (S) is illustrated using the quadrangular pyramid shape of FIG. FIG. 2A shows the relationship between the first radio wave absorber 2 and the ferrite radio wave absorber 3, and the radio wave absorption characteristics are the characteristic measurement results of the legend B shown in FIGS. 6A and 6B described later. This corresponds to the structure of a radio wave absorber conventionally used. FIG. 2B shows a state in which the second radio wave absorber 1 is disposed only in the central portion of the area of the first radio wave absorber 2, and FIG. The state which has arrange | positioned the 2nd electromagnetic wave absorber 1 in the substantially whole region is shown.

  FIG. 3 shows a second wave absorber 1 having a solid structure corresponding to the first wave absorber 2 having a quadrangular pyramid shape. FIG. 3A is a side projection when the second radio wave absorber 1 is smaller than the first radio wave absorber 2. FIG. 3B shows a case where the height of the first radio wave absorber 2 and the height of the second radio wave absorber 1 are substantially the same, and FIG. 3C is larger than the height of the first radio wave absorber 2. 4 is a side projection view of the second radio wave body 1. FIG. Although FIG. 3 shows a solid structure, the present invention is not limited to this, and a hollow structure may be used.

  FIG. 4 shows an example of the alignment shape (S). Cone shape FIG. 4 (a), quadrangular pyramid shape FIG. 4 (b), wedge shape FIG. 4 (c), truncated cone shape FIG. 4 (d), square frustum shape FIG. 4 (e), wedge trap shape 4 (f), cross-girder shape FIG. 4 (g) and cross-girder shape FIG. In addition to these shapes, the alignment shape (S) may be a cone having a curved surface as well as a horizontal plane. That is, the shape is not particularly limited as long as the shape can exhibit the radio wave absorption characteristics.

FIG. 5A shows a state in which the second radio wave absorber 1 of FIG. FIG. 5B is a cross-sectional view taken along the line AA ′ of FIG. 5A, a cross-sectional view showing the solid structure 20 from the left, and a cross-sectional view showing a cross section of the hollow structure 21 manufactured by a bent structure at the center. And the right is a sectional view showing a state 22 in which a material having radio wave absorption characteristics due to dielectric loss is fed into the hollow structure 21. Note that the solid portion of the state 22 that forms the solid structure may be the whole or a part of the hollow portion of the 21, and the characteristics may be improved by specifying the location, or the total amount of radio wave absorption increases without specifying The radio wave absorption characteristics may be improved.

FIG. 6 shows the characteristic improvement effect of the radio wave absorber 100 obtained by the manufacturing method according to the present invention. FIG. 6A is a graph showing a frequency band of 30 MHz to 300 MHz, and FIG. 6B is a graph showing a radio wave absorption characteristic (ABSORPTION (dB)) of a frequency band of 2 GHz to 18 GHz. In FIG. 6A and FIG. 6B, the value of the legend A indicates the radio wave absorption characteristic when only the ferrite radio wave absorber 3 shown in FIG. 1C is used, and FIG. ) Shows the radio wave absorption characteristics when only the first radio wave absorber 2 is provided, Legend C shows the radio wave absorption characteristics when the characteristics are adjusted by the conventional technology, and Legend D shows the second radio wave according to the present invention. The radio wave absorption characteristics with the absorber 1 added are shown.

  FIG. 6 shows the frequency characteristics of the radio wave absorption characteristics of the radio wave absorber 100 obtained by the manufacturing method according to the present invention. The value on the vertical axis is on the lower side of the graph, that is, the radio wave absorption due to absorption. The larger the value, the better the evaluation method. In general, it is desirable to have a radio wave absorption characteristic with little change in all frequency bands to be measured. In FIG. 6 (a), the value of D in FIG. 6 (a), which is the result of implementing the present invention, compared to the maximum values of B in FIG. 6 (a) and C in FIG. It can be seen that the maximum value is small and the characteristics are excellent.

In addition, in the frequency region of FIG. 6B, D in FIG. 6B is a material such as moisture compared to B in FIG. 6B and C in FIG. 6B corresponding to the conventional embodiment. It can be seen that not only the steep changes in the radio wave absorption characteristics derived from the elements constituting the are suppressed, but also that the values decrease on average. In particular, it can be seen that the value of C in FIG. 6B is large and small at a portion of 13 GHz or less. Thus, by using the manufacturing method of the radio wave absorber using the second radio wave absorber 1 to be added according to the present invention, the conventional construction method C in FIG. 6 and B in FIG. 6 immediately after the construction of the first radio wave absorber 2 are used. The improvement effect of the radio wave absorption characteristics was obtained for each.

  In addition, according to the manufacturing method of the radio wave absorber 100 and the second radio wave absorber 1 according to the present invention, not only dielectric loss but also an additional absorber for improving the characteristics of an anechoic chamber using an absorber in an audible frequency region. Can be used in a wide range, such as

1. Second electromagnetic wave absorber 2. First electromagnetic wave absorber 3. Ferrite wave absorber 20. Solid structure 21. Hollow structure 22. Solid structure part 100 inside hollow structure. In the case of a ferrite electromagnetic wave absorber alone When a first electromagnetic wave absorber is added to ferrite C.I. When characteristics are adjusted by conventional techniques When a second electromagnetic wave absorber is added Aligned shape Arrangement shape

Claims (9)

  A method of manufacturing a radio wave absorber, which is obtained by a molding step for obtaining a second radio wave absorber comprising a matching shape and an arrangement shape, or a combination thereof, or a shape including these, and the molding step. And a mounting process for adding the second radio wave absorber to the existing first radio wave absorber, and a radio wave absorber manufacturing method that improves radio wave absorption characteristics through the two steps. The method for manufacturing a radio wave absorber according to claim 1, wherein the addition of the second radio wave absorber to the first radio wave absorber is intended to increase the total amount of the radio wave absorber. Method of manufacturing a radio wave absorber. In the method for manufacturing a radio wave absorber, the addition of the second radio wave absorber to the first radio wave absorber is intended to improve radio wave absorption characteristics in a desired frequency region. The manufacturing method of the electromagnetic wave absorber of Claim 1 or Claim 2.   A second radio wave absorber used in the method for manufacturing a radio wave absorber according to any one of claims 1 to 3, wherein an overall shape thereof is an alignment shape and an arrangement shape, or a combination shape thereof, Or a shape including these, and the matching shape is a shape composed of any one of a cone, a frustum, a wedge shape, a cross-girder shape exhibiting radio wave absorption characteristics, or a combination thereof, and the arrangement The installation shape is a shape necessary for disposing and fixing the second radio wave absorber in contact with a valley portion of the first radio wave absorber. The second radio wave absorber used in the method for manufacturing a radio wave absorber according to any one of claims 1 to 3, wherein the inside thereof has a hollow structure. The second wave absorber. A second radio wave absorber for use in the method for manufacturing a radio wave absorber according to any one of claims 1 to 3, wherein the inside thereof has a solid structure. 2nd electromagnetic wave absorber of description.   A second radio wave absorber used in the method for manufacturing a radio wave absorber according to any one of claims 1 to 3, wherein the manufacturing method can be formed by bending a thin plate member. The second electromagnetic wave absorber according to claim 4 or 5, wherein:   A second radio wave absorber for use in the method for manufacturing a radio wave absorber according to any one of claims 1 to 3, wherein the second radio wave absorber has a hollow structure with an overall shape. The solid structure is manufactured by manufacturing, and then supplying a foamable material or a liquid having dielectric loss into the interior to be cured, or supplying powder, or a combination thereof. The second electromagnetic wave absorber according to any one of claims 4, 6 and 7. A second wave absorber for use in the method of manufacturing a wave absorber according to any one of claims 1 to 3, wherein the concentration distribution is obtained by mixing or applying a carbon fiber or a material having a large dielectric loss. 9. The second radio wave absorber according to claim 4, wherein the second radio wave absorber has good radio wave absorption performance in a frequency range of 30 MHz to 26.5 GHz with a uniform or gradient distribution.