WO2009128377A1 - 複合型電波吸収体 - Google Patents
複合型電波吸収体 Download PDFInfo
- Publication number
- WO2009128377A1 WO2009128377A1 PCT/JP2009/057211 JP2009057211W WO2009128377A1 WO 2009128377 A1 WO2009128377 A1 WO 2009128377A1 JP 2009057211 W JP2009057211 W JP 2009057211W WO 2009128377 A1 WO2009128377 A1 WO 2009128377A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- radio wave
- wave absorber
- absorber
- plate
- magnetic
- Prior art date
Links
Images
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01Q—ANTENNAS, i.e. RADIO AERIALS
- H01Q17/00—Devices for absorbing waves radiated from an antenna; Combinations of such devices with active antenna elements or systems
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01Q—ANTENNAS, i.e. RADIO AERIALS
- H01Q17/00—Devices for absorbing waves radiated from an antenna; Combinations of such devices with active antenna elements or systems
- H01Q17/008—Devices for absorbing waves radiated from an antenna; Combinations of such devices with active antenna elements or systems with a particular shape
-
- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
- H05K9/00—Screening of apparatus or components against electric or magnetic fields
- H05K9/0001—Rooms or chambers
- H05K9/0003—Shielded walls, floors, ceilings, e.g. wallpaper, wall panel, electro-conductive plaster, concrete, cement, mortar
Definitions
- the present invention relates to a radio wave absorber that absorbs electromagnetic waves, and more particularly to a composite radio wave absorber used in an anechoic chamber.
- An anechoic chamber is an EMC (Electro) that evaluates electromagnetic interference (noise) generated from various electronic devices and evaluates the resistance of electronic devices against external electromagnetic noise. Widely used as a measurement room for evaluation of Magnetic Compatibility). In recent years, an anechoic chamber has come to be used as a calibration measurement chamber for calibrating an antenna in addition to the above applications. Anechoic chambers are roughly classified into three types according to size: a small anechoic chamber, a 3 m method anechoic chamber, and a 10 m method anechoic chamber, and the type of anechoic chamber to be used is determined by the measurement object and measurement method.
- a radio wave absorber is installed on the side wall, ceiling, and floor of the anechoic chamber.
- the configuration of the electromagnetic wave absorber varies depending on the required characteristics and size of the installed anechoic chamber.
- a composite wave absorber having a basic configuration in which a ferrite tile that is a magnetic absorber plate and a dielectric loss body are combined is often used.
- electromagnetic waves in a frequency band of 300 MHz or higher are absorbed by a dielectric loss body, and electromagnetic waves in a frequency band lower than that are absorbed by a ferrite tile. Therefore, excellent electromagnetic wave absorption characteristics in a wide frequency band are obtained. It is known to exert.
- a dielectric loss body is comprised with the material which mixed conductive materials, such as carbon black and graphite, in base materials, such as a foamed polystyrene and a foaming urethane.
- base materials such as a foamed polystyrene and a foaming urethane.
- a radio wave absorber molded into a wedge shape or a pyramid shape is used as the shape.
- the pyramid shape is known to have no shape anisotropy and to efficiently absorb electromagnetic waves with various incident angles, and is used in many anechoic chambers.
- the height of a wedge-shaped or pyramid-shaped wave absorber depends on the size of the anechoic chamber, but in order to cope with electromagnetic waves in a wide frequency band, it is generally a large wave of about 0.5m to 2.0m. Absorbers are needed. For this reason, the conventional solid electromagnetic wave absorber has a problem in workability due to an increase in weight and volume.
- the cross-type radio wave absorber is excellent in impedance matching, and the radio wave absorption characteristics in the high frequency band can be improved by the small radio wave absorber. Therefore, it is possible to reduce costs while maintaining excellent radio wave absorption characteristics.
- the present invention has been made in view of the above circumstances, and an object thereof is to provide a radio wave absorber having excellent radio wave absorption characteristics with a return loss of 20 dB or more in a wide frequency band of 30 MHz to 20 GHz.
- the present inventors have developed a magnetic absorber plate, a cross-type radio wave absorber installed on the magnetic absorber plate, and a dielectric of the cross-type radio wave absorber on the magnetic absorber plate.
- the structure of the small wave absorber is composed of a plurality of wave absorption layers in a direction perpendicular to the magnetic absorber plate, Radio wave absorption characteristics in the high frequency band while maintaining the radio wave absorption characteristics in the low frequency band by adopting a multilayer structure with a low dielectric constant layer having a dielectric constant lower than that of the radio wave absorption layer.
- the present invention has been completed.
- the composite wave absorber of the present invention includes a magnetic absorber plate, a cross-type wave absorber crossing a plurality of dielectric loss plates arranged perpendicular to the magnetic absorber plate, and a magnetic absorber plate.
- the electromagnetic wave is absorbed multiple times. It is possible to effectively absorb electromagnetic waves in a wider frequency band by the synergistic effect of the electromagnetic wave attenuation effect due to heat conversion in each radio wave absorption layer and the electromagnetic wave cancellation effect due to the phase difference. it can. Since the above effect is realized without increasing the concentration of the conductive material contained in the radio wave absorber, it is not necessary to increase the concentration of the conductive material in order to improve the radio wave absorption characteristics in the high frequency band. For this reason, the radio wave absorbing performance in the low frequency band by the magnetic absorber plate can be sufficiently exhibited, and excellent radio wave absorption characteristics can be obtained over a wide frequency band from the low frequency band to the high frequency band.
- FIG. 1 shows an example of the composite wave absorber of the present invention.
- the composite wave absorber 1 of the present invention includes a magnetic absorber plate 2, a cross-type radio wave absorber 3 installed on the magnetic absorber plate 2, and a cross-type radio wave absorber 3 on the magnetic absorber plate 2.
- a small electromagnetic wave absorber 4 installed in a partitioned space is provided as a basic configuration.
- the cross type wave absorber 3 is provided on the magnetic absorber plate 2
- the vertical direction with respect to the plate 2 is defined as the up and down direction
- the cross type wave absorber 3 side is defined as the upper side. explain.
- the magnetic absorber plate 2 a ferrite tile is generally used.
- the cross-type electromagnetic wave absorber 3 is composed of a plate material made of a dielectric loss material.
- the structure of the plate material usually includes a sheet form, a corrugated board structure, a honeycomb structure or the like.
- dielectric loss materials include carbon-containing foamed urethane, carbon-containing foamed styrene, and carbon-containing foamed polypropylene.
- an inorganic material such as plastic, paper, silica, or alumina containing carbon or coated with a carbon layer can be used as the dielectric loss material.
- the carbon content in the dielectric loss material is usually in the range of 0.05 mass% to 1.5 mass%, preferably 0.05 mass% to 1 mass%.
- the cross-type electromagnetic wave absorber 3 is usually formed by intersecting polygonal dielectric loss material plates made of dielectric loss material.
- An example of the cross-type electromagnetic wave absorber 3 is shown in FIGS. 2 (A) and 2 (B).
- a polygonal dielectric loss plate 33 (FIG. 2A) having a vertically long notch at the upper center and a polygonal dielectric loss plate 33 having a vertically long notch at the bottom center. (FIG. 2 (B)) is produced, and it forms by fitting each other in a notch part (refer FIG. 3 (A)). In this state, it is arranged perpendicular to the magnetic absorber plate 2.
- crossed means that at least a part of two or more dielectric loss materials intersect in a cross section parallel to the magnetic absorber plate 2 on which the cross type wave absorber 3 is placed.
- the cross-type electromagnetic wave absorber 3 has a structure in which the dielectric loss body plate 33 intersects when viewed in a cross section parallel to the magnetic absorber plate 2, its manufacturing method is not particularly limited. For example, it can be formed by bonding two bent dielectric loss plates.
- the cross-type electromagnetic wave absorber 3 is preferably installed directly on the magnetic absorber plate 2. However, an intermediate layer can be appropriately provided between the magnetic absorber plate and the cross-type electromagnetic wave absorber as long as the characteristics of the magnetic absorber are not affected.
- a deformed hexagon (a shape obtained by cutting each vertex of an isosceles triangle) is used as an example of the polygonal shape of the dielectric loss body plate 33.
- the shape of the dielectric loss plate 33 is not limited to this.
- a cross-type electromagnetic wave absorber can be formed by intersecting dielectric loss plates such as a triangle, a quadrangle (rectangular), and a pentagon.
- a shape in which the width of the dielectric loss plate is narrowed from the bottom of the cross-type wave absorber (the lower portion close to the magnetic absorber plate) toward the top of the tip is preferable.
- each side may be a straight line or a curved line.
- the inclined structure include a linear inclined structure as shown in FIG. 3A and a curved inclined structure as shown in FIG. 3B.
- the tip angle ⁇ of the cross-type electromagnetic wave absorber is preferably 1 ° to 45 °, and more preferably 5 ° to 30 ° (see FIG. 2A). There is a limit in setting the size of the anechoic chamber to a large size.
- a typical dark room size of a 10 m method anechoic chamber widely used for EMC evaluation is 15 m ⁇ 24 m ⁇ 9 m (height).
- the bottom area of the electromagnetic wave absorber installed in the anechoic chamber is determined in consideration of cost and workability, and generally one side is set to about 600 mm.
- the height of the radio wave absorber is preferably set to 600 mm to 2000 mm. Depending on the required performance of the anechoic chamber, the height and the tip angle ⁇ of the cross-type electromagnetic wave absorber are appropriately adjusted.
- the thickness of the low dielectric constant layer 11 in the vertical direction is t 11 (mm)
- the dielectric constants of the radio wave absorption layers 12 and 13 are ⁇ 12 , ⁇ 13
- the thickness of 13 in the vertical direction is t 12 (mm) and t 13 (mm).
- the low dielectric constant layer 11 and the radio wave absorption layers 12 and 13 can sufficiently exhibit the radio wave absorption performance in the low frequency band by the magnetic absorber plate 2 and are excellent over a wide frequency band from the low frequency band to the high frequency band. It is necessary to set a characteristic value that can obtain radio wave absorption performance.
- the range of the characteristic values of the radio wave absorption layers 12 and 13 is the product of the respective dielectric constants ( ⁇ 12 , ⁇ 13 ) and thicknesses (t 12 , t 13 ) ( ⁇ 12 ⁇ t 12 , ⁇ 13 ⁇ t 13 ).
- the product of the dielectric constant and the thickness (mm) is preferably 10 to 40, more preferably 20 to 35.
- the thickness t 11 (mm) of the low dielectric constant layer 11 varies depending on the characteristic values of the radio wave absorption layers 12 and 13.
- the radio wave absorption layers 12 and 13 are preferably set to 10 mm to 500 mm.
- the radio wave absorption layers 12 and 13 themselves can sufficiently absorb radio waves. A sufficient absorption performance can be obtained even near t 11 (mm).
- the radio wave absorption layers 12 and 13 themselves have low radio wave absorption performance, so that t 11 (mm) is set near the upper limit in order to obtain sufficient absorption performance. It is more preferable.
- FIG. 4 shows a side view of the composite wave absorber of the present invention shown in FIG.
- the small electromagnetic wave absorber 4 having a shape (swash plate structure) inclined from the dielectric loss plate 33 toward the magnetic absorber plate 2 in a space defined by the dielectric loss plate 33 on the magnetic absorber plate 2.
- the small wave absorber 4 is formed by two swash plates 121 and 123 arranged in parallel and two vertical plates 122 connecting the swash plates 121 and 123, and the inside is a low dielectric constant layer. (In this example, it is a space layer) 11.
- the small radio wave absorber 4 has a structure having two radio wave absorption layers 12 and 13 (swash plates 121 and 123) via the low dielectric constant layer 11 in the vertical direction.
- the electromagnetic wave reaches the radio wave absorption layers 12 and 13 a plurality of times.
- Each of the radio wave absorption layers 12 and 13 provides a synergistic effect of the electromagnetic wave attenuation effect due to heat conversion and the electromagnetic wave cancellation effect due to the phase difference. Thereby, the electromagnetic wave of a wider frequency band can be absorbed effectively.
- the effects as described above can be achieved, and the radio wave absorption characteristics in the high frequency band can be improved without increasing the concentration of the conductive material contained in the radio wave absorber plate.
- the effect can be sufficiently exhibited, and excellent radio wave absorption characteristics can be obtained over a wide frequency band from the low frequency band to the high frequency band.
- the effect of the present invention can be obtained by interposing a low dielectric constant layer filled with gas or solid so that the dielectric constant is lower than that of the radio wave absorption layer between the radio wave absorption layers.
- the dielectric constant of the low dielectric constant layer is preferably 3 or less, and more preferably an air layer (space layer) in consideration of the dielectric constant and cost.
- the small electromagnetic wave absorber 4 formed from two swash plates 121 and 123 and a vertical plate 122 is used, but the present invention is not limited to this. If there are two or more wave absorber plates 121 and 123 through the space layer (low dielectric constant layer) 11, the effect of the present invention is realized. However, for the following reason, it is possible to deal with a wider range of electromagnetic waves, and the structure is stable. Therefore, it is preferable that the small wave absorber 4 has the vertical plate 122.
- the wavelength from the vertically upward direction is a portion that becomes a valley between adjacent wave absorbers, that is, a lower portion where the small wave absorber 4 contacts the magnetic absorber plate 2
- the presence of the vertical plate 122 has the advantage that the radio wave absorber plates 121 and 123 are separated and supported, and at the same time, the electromagnetic waves can be sufficiently absorbed by the vertical plate 122 without directly reaching the magnetic absorber plate 2. .
- the small wave absorber 4 having a swash plate structure shown in FIG. 4 is formed by, for example, bending the dotted line portion of the rectangular wave absorber plate shown in FIG. 5 and attaching an adhesive or the like to the marginal portion d to adhere to the corresponding portion. It can be formed easily.
- the small wave absorber having a swash plate structure is very advantageous in terms of workability and cost.
- it is preferable that the small wave absorbers 4 having a swash plate structure disposed in four spaces partitioned by the dielectric loss plate are disposed in different directions. By adopting such a structure, there is no polarization dependence, and electromagnetic waves coming from various angles can be effectively absorbed.
- the electromagnetic wave attenuation effect and the phase difference due to the multiple times of heat conversion in the radio wave absorption layer uses a synergistic effect with the cancellation effect of electromagnetic waves.
- the thickness of the low dielectric constant layer 11 can be changed and the performance can be adjusted.
- the thickness of the low dielectric constant layer is preferably set to 10 mm to 500 mm, although it depends on the overall size of the radio wave absorber.
- the “thickness of the low dielectric constant layer” refers to the dimension in the vertical direction of the low dielectric constant layer 11 (perpendicular to the magnetic absorber plate 2) as indicated by h in FIG.
- the small radio wave absorber 4 of the present invention is characterized by having a plurality of radio wave absorption layers 12 and 13 with a low dielectric constant layer 11 in a direction perpendicular to the magnetic absorber plate 2. For example, even in a configuration in which two radio wave absorption layers 12 and 13 with a low dielectric constant layer 11 disposed in parallel with the magnetic absorber plate 2 can be provided, it can cope with a predetermined electromagnetic wave. More preferably, the present invention includes a structure in which the small electromagnetic wave absorber 4 is inclined at a predetermined angle with respect to the magnetic absorber plate 2. With this structure, a sufficient electromagnetic wave scattering effect is obtained, and more excellent radio wave absorption characteristics are realized.
- the height (dimension in the vertical direction) of the absorber is preferably set to 200 mm to 700 mm.
- the “size (height) in the vertical direction of the small wave absorber” in the present invention is the lowest from the bottom of the small wave absorber 4 in contact with the magnetic absorber plate 2 as indicated by i in FIG. It is the dimension in the vertical direction to the top.
- the small electromagnetic wave absorber 4 is installed so as to cover the entire magnetic absorber plate 2 in a plan view as viewed from above so that electromagnetic waves in a high frequency band do not reach the magnetic absorber plate 2 directly. Preferably it is done.
- the structure of the small electromagnetic wave absorber 4 according to the present invention is not limited to the swash plate structure, and may be, for example, a pyramid shape shown in FIG. 6A or a wedge shape shown in FIG. Even when the small wave absorber 4 has a pyramid shape and a wedge shape, it is necessary to have a plurality of wave absorption layers with a low dielectric constant layer interposed in the direction perpendicular to the magnetic absorber plate 2. For example, when the composite wave absorber shown in FIG. 6A is viewed from above, a difference from the conventional composite wave absorber cannot be recognized at first glance.
- the small electromagnetic wave absorber 4 when viewed in a vertical section, it is composed of two swash plates with a low dielectric constant layer interposed therebetween. As a result, a synergistic effect of the electromagnetic wave attenuation effect by the plurality of pyramidal absorption layers and the electromagnetic wave cancellation effect by the phase difference can be obtained as in the case of the small wave absorber having the multilayered swash plate structure.
- FIG. 6 (A) four pyramid structures are arranged for each space divided by dielectric loss plate. The number of pyramid structures depends on the overall size and required performance of the composite wave absorber. It can also be changed as appropriate.
- a regular square tube structure is disposed under the pyramid structure, but the pyramid structure may be directly installed on the magnetic absorber plate.
- a pyramid structure in which two pyramid shapes having different sizes are stacked is directly placed on the magnetic absorber plate (the thickness of the low dielectric constant layer is constant).
- 6 (D) includes a structure in which a pyramid structure in which two pyramid shapes having different inclinations are stacked is directly placed on a magnetic absorber plate (the thickness of the low dielectric constant layer is changed).
- the wedge shape is not shown in the figure, but a wedge shape whose cross-sectional shape is the shape of the left and right half of the pyramid cross section is given as an example.
- a regular rectangular tube structure is disposed as shown in FIG. It is preferable to do this.
- the small electromagnetic wave absorber is arranged so that the magnetic absorber plate is covered and seen from above.
- the wedge-shaped small electromagnetic wave absorber shown in FIG. 6B is also formed by a plurality of swash plates arranged in parallel and a low dielectric constant layer therebetween.
- a synergistic effect of the electromagnetic wave attenuation effect by the wedge-shaped absorption layers and the electromagnetic wave cancellation effect by the phase difference can be obtained as in the case of the multi-layer swash plate structure or the pyramid-shaped small wave absorber.
- one wedge structure is arranged for each space partitioned by the dielectric loss plate. The number of wedge structures depends on the overall size and required performance of the composite wave absorber. It can also be changed accordingly.
- FIG. 6B one wedge structure is arranged for each space partitioned by the dielectric loss plate. The number of wedge structures depends on the overall size and required performance of the composite wave absorber. It can also be changed accordingly.
- a vertical plate is disposed between the outer wedge-shaped swash plate and the magnetic absorber plate, but the wedge structure can also be installed directly on the magnetic absorber plate.
- a vertical plate is preferably arranged. Further, it is preferable that the small electromagnetic wave absorber is arranged so that the magnetic absorber plate is covered and seen from above.
- the small wave absorber 4 described above is also made of a plate material made of a dielectric loss material, like the cross type wave absorber.
- the structure of the plate material include a sheet shape, a cardboard structure, and a honeycomb structure.
- dielectric loss materials include carbon-containing foamed urethane, carbon-containing foamed styrene, and carbon-containing foamed polypropylene.
- an inorganic material such as plastic, paper, silica, or alumina containing carbon or coated with a carbon layer can be used as the dielectric loss material.
- Examples of carbon used as the conductive material include carbon black and graphite powders as well as fibrous materials such as carbon fibers and carbon nanotubes.
- the small wave absorber may be formed separately from the cross-type wave absorber.
- the conductive material content of the small wave absorber can be changed to the conductive material content of the cross-type wave absorber.
- the small electromagnetic wave absorber of the present invention has a synergistic effect between the electromagnetic wave attenuation effect by the multiple radio wave absorption layers and the electromagnetic wave cancellation effect by the phase difference by arranging the multiple radio wave absorption layers through the low dielectric constant layer. Use. Therefore, it is possible to improve the radio wave absorption characteristics in the high frequency band while adjusting the content of the conductive material in the small radio wave absorber to an appropriate low concentration so as not to disturb the absorption performance of the magnetic absorber plate.
- the content of the conductive material varies depending on the type and form of the conductive material.
- powdery carbon such as graphite
- fibrous carbon such as carbon fiber
- the fiber length is preferably 0.5 mm to 7 mm. In this case, optimum conductivity is obtained.
- flame retardance can be imparted by applying a flame retardant to the dielectric loss plate constituting the cross-type wave absorber and the conductive sheet constituting the small wave absorber.
- a flame retardant solution having a predetermined concentration or a flame retardant solution having a predetermined concentration is applied to the dielectric loss plate or the conductive sheet, and then dried.
- the flame retardant performance and non-flammability performance of the radio wave absorber are improved, and it is also possible to obtain a radio wave absorber material conforming to the “non-combustible material” of the Building Standard Law.
- the radio wave absorber obtained by the above method does not require the addition of a non-combustible board or the like, and it is relatively easy to obtain a radio wave absorber that is lightweight and excellent in non-combustible performance.
- the obtained flame-retardant electromagnetic wave absorber can be applied to an anechoic chamber for automobiles and automobile parts in which an EMI (Electro Magnetic Interference) test is required at high power.
- the flame retardant is not particularly limited as long as it can be applied to a constituent material of a radio wave absorber such as a dielectric loss plate or a conductive sheet, but a boric acid or phosphoric acid flame retardant is preferable.
- boric acid compounds include known flame retardants such as sodium borate, potassium borate, magnesium borate, strontium borate, and zinc borate.
- phosphate compound include known flame retardants such as sodium phosphate, potassium phosphate, calcium phosphate, zinc phosphate, and ammonium polyphosphate.
- the amount of the flame retardant added is preferably 5 to 50% by mass, more preferably 10 to 30% by mass, based on the mass of each plate material.
- a 15 mm thick honeycomb structure made of a paper non-conductive sheet was cut into a trapezoidal shape having a bottom portion (lower side) of 600 mm, a tip portion (upper side) of 100 mm, and a height of 1400 mm.
- Two plates of this shape were produced as basic members of a cross-type wave absorber.
- a conductive sheet made of paper kneaded with carbon fibers having a fiber length of 6 mm and a fiber diameter of 7 ⁇ m is bonded to the front and back of the two basic members, did.
- the carbon content in the entire dielectric loss plate was 0.1% by mass.
- One of the obtained dielectric loss plates was notched in the upper part, and the other was notched in the lower part (see FIGS. 2A and 2B).
- a cross-type electromagnetic wave absorber was formed by fitting the notches into each other.
- the cross type wave absorber is installed on a ferrite tile, and the following Examples 1 to 4 and Comparative Examples 1 to 3 are placed in a space partitioned by a dielectric loss plate (cross type wave absorber) on the ferrite tile.
- Each of the small wave absorbers manufactured by the above was installed to obtain a composite wave absorber.
- Example 1 A carbon sheet having a fiber length of 3 mm and a fiber diameter of 7 ⁇ m was dispersed so that the carbon content in the pulp was 1% by mass, and paper was made to produce a conductive sheet.
- the conductive sheet was attached to the front and back surfaces of a paper non-conductive sheet as a middle core to produce a corrugated cardboard sheet having a thickness of 3 mm and cut into 300 mm (width) ⁇ 1530 mm (length).
- seat was 0.4 mass%. According to the development shown in FIG.
- Rate layer A two-layered wave absorber layer structure with a thickness of 150 mm.
- the small wave absorber having this structure is arranged obliquely in different directions in four spaces partitioned by a cross-type wave absorber to form a swash plate structure. Produced.
- Example 2 A small wave absorber was produced using the same corrugated cardboard sheet as in Example 1. Here, everything was the same as in Example 1 except that b in the developed view shown in FIG. 5 was set to 100 mm and the space layer (low dielectric constant layer) was set to 100 mm.
- Example 3 A plurality of hollow quadrangular pyramids (pyramid shapes) were produced from the development shown in FIG. 7 (A) using the same corrugated cardboard sheet as in Example 1.
- the length e of the base of the quadrangular pyramid was 150 mm
- the height f was 500 mm.
- a plurality of regular square cylinders having a base e of 150 mm and a height g of 100 mm were produced from the development shown in FIG. 7B.
- FIG. 7 (D) the base of one square pyramid and the base of the other quadrangular pyramid were combined at the upper and lower sides of the regular square cylinder, respectively.
- radio wave absorber having a two-layer structure was formed so that a space layer (low dielectric constant layer) of 100 mm was formed inside.
- a total of 16 radio wave absorbers formed in this manner were arranged in 4 spaces each divided by a cross type radio wave absorber to form a composite radio wave absorber.
- Example 4 A conductive sheet was prepared by dispersing a graphite powder having a particle size of 4 ⁇ m so that the carbon content in the pulp was 20% by mass, and making paper.
- a corrugated cardboard sheet having a thickness of 3 mm was produced by attaching the conductive sheet to the front and back surfaces of a paper non-conductive sheet as a center. The carbon content with respect to the mass of the entire cardboard sheet was 8% by mass.
- a small-sized wave absorber having a two-layer structure was produced in the same manner as in Example 1, and a composite wave absorber was produced by installing on a ferrite tile as in Example 1. .
- Example 5 A composite wave absorber was produced in the same manner as in Example 1 except that flame resistance was previously imparted to the conductive sheet and honeycomb structure constituting the wave absorber using a flame retardant.
- a flame retardant used, Fireless B manufactured by Trust Life Co., Ltd. was used.
- the conductive sheet was applied with a flame retardant solution adjusted to a solid content concentration of 25% with a coating machine, and then dried at 100 ° C. for 1 hour to perform incombustibility treatment. After the incombustible treatment, 10% of the flame retardant solid content was included with respect to the mass of the conductive sheet.
- the honeycomb structure was impregnated in an impregnation tank containing a flame retardant solution having a solid content concentration of 25% for a predetermined time, and then dried at 100 ° C. for 1 hour to perform an incombustible treatment. After the incombustible treatment, 13% of the flame retardant solid content was included with respect to the mass of the honeycomb structure.
- Example 1 Using a corrugated cardboard sheet similar to that used in Example 3, a quadrangular pyramid and regular square tube absorber was formed in the same manner as in Example 3.
- a single-layer structure wave absorber was manufactured by combining one regular square tube with one square pyramid.
- a total of 16 of the obtained radio wave absorbers were arranged in 4 spaces divided by the cross type radio wave absorber in the same manner as in Example 3 to obtain a composite radio wave absorber.
- Comparative Example 2 A carbon sheet having a fiber length of 3 mm and a fiber diameter of 7 ⁇ m was dispersed in the pulp so that the carbon content was 4% by mass, and paper making was performed to produce a conductive sheet.
- a corrugated cardboard sheet having a thickness of 3 mm was produced by attaching the conductive sheet to the front and back surfaces of a paper non-conductive sheet as a center. The carbon content with respect to the mass of the entire cardboard sheet was 1.6% by mass.
- a single-layer wave absorber having a shape in which one square pyramid and one regular square tube were combined was produced.
- four of these radio wave absorbers were arranged in 4 spaces divided by the cross type radio wave absorber, to obtain a composite radio wave absorber.
- Example 3 (Comparative Example 3) Using the same corrugated cardboard sheet as in Example 3, a radio wave absorber having a shape in which a quadrangular pyramid and a regular square tube were combined as in Example 3 was formed. Here, it was set as the two-layer structure electromagnetic wave absorber with which the pyramid of the close_contact
- Table 1 shows the results of measuring the radio wave absorption characteristics of the composite wave absorbers of Examples 1 to 4 and Comparative Examples 1 to 3.
- the radio wave absorption characteristics were evaluated by the coaxial tube method on the low frequency side of 30 MHz to 1 GHz and by the normal incidence method on the high frequency side of 1 GHz to 20 GHz.
- Comparative Example 1 having a single layer structure, sufficient radio wave absorption characteristics cannot be obtained in a high frequency band.
- Comparative Example 2 having a single layer structure and an increased carbon concentration the radio wave absorption characteristics in the high frequency band are improved.
- the radio wave absorption characteristics in the low frequency band have deteriorated.
- the radio wave absorbers (Examples 1 to 4) of the present invention having a plurality of radio wave absorption layers via the space layer (low dielectric constant layer) all have good radio wave absorption characteristics of 20 dB to 40 dB at 30 MHz to 18 GHz. It was confirmed to have. Although not described in Table 1, it has been confirmed that good radio wave absorption characteristics can be obtained even at 20 GHz in all examples.
- FIG. 5 is a perspective view ((A) (B)) showing another example of the composite wave absorber of the present invention and a cross-sectional view ((C) (D)) showing a modification thereof.
- Example 4 is a development view ((A) (B)) forming a small electromagnetic wave absorber of Example 3, a perspective view (C) and a sectional view (D) of the completed small electromagnetic wave absorber. It is a figure which shows the nonflammable performance evaluation result of the electromagnetic wave absorber of Example 5 and Comparative Example 1.
Landscapes
- Engineering & Computer Science (AREA)
- Microelectronics & Electronic Packaging (AREA)
- Shielding Devices Or Components To Electric Or Magnetic Fields (AREA)
- Hard Magnetic Materials (AREA)
Abstract
Description
Magnetic Compatibility)評価用測定室として、広く利用されている。また、近年は、上記用途の他にアンテナを校正するための校正測定室としても電波暗室が利用されるようになっている。電波暗室はサイズによって、小型電波暗室、3m法電波暗室、及び10m法電波暗室の3種類に大別され、使用する電波暗室の種類は、測定物や測定方法により決められる。
一般に、誘電損失体は、発泡ポリスチレンや発泡ウレタン等の基材にカーボンブラックやグラファイト等の導電材料を混入した材料で構成される。形状としてはくさび形状やピラミッド形状に成型した電波吸収体が用いられている。特に、ピラミッド形状は、形状の異方性が無く、様々な入射角度の電磁波を効率よく吸収できることが知られ、多くの電波暗室で利用されている。くさび形状又はピラミッド形状の電波吸収体の高さは、電波暗室のサイズにも依存するが、幅広い周波数帯域の電磁波に対応するためには、一般に、0.5m~2.0m程度の大型の電波吸収体が必要とされている。このため、従来の中実の電波吸収体では、重量及び体積が大きくなり、施工性に問題があった。
特許文献1の複合型電波吸収体では、小型電波吸収体に含有される導電性材料の濃度、即ち、カーボン濃度を向上させることにより、高周波数帯域における電波吸収特性を向上させることができる。しかし、小型電波吸収体のカーボン濃度を高くすると、小型電波吸収体により電磁波が反射し、電磁波の磁性吸収体板への到達が妨げられる。このため、磁性吸収体板による電波吸収性能が発揮されることなく、低周波数帯域での電波吸収特性が低下するという問題があった。このように、現状では、30MHz~20GHzという幅広い周波数帯域にわたって優れた電波吸収性能を有する電波吸収体は得られていない。
図1に本発明の複合型電波吸収体の一例を示す。本発明の複合型電波吸収体1は、磁性吸収体板2、磁性吸収体板2上に設置されたクロス型電波吸収体3、及び磁性吸収体板2上の、クロス型電波吸収体3に区切られた空間に設置された小型電波吸収体4を基本構成として備える。なお、磁性吸収体板2上にクロス型電波吸収体3を設けている構造から、以下の説明においては板2に対する垂直方向を上下方向とし、クロス型電波吸収体3側を上側と定義して説明する。従って個別の記述においては方向の説明は基本的に省略する。
磁性吸収体板2としては、一般にフェライトタイルが用いられる。
クロス型電波吸収体3は、誘電損失材料からなる板材で構成される。板材の構造としては、通常は、シート状、段ボール構造又はハニカム構造等が挙げられる。具体的な誘電損失材料の例としては、カーボン含有発泡ウレタン、カーボン含有発泡スチレン、カーボン含有発泡ポリプロピレン等が挙げられる。また、カーボンを含有し、若しくはカーボン層を塗布したプラスティック、紙、シリカやアルミナ等の無機材料も誘電損失材料として用いることができる。誘電損失材料中のカーボン含有率は、通常、0.05質量%~1.5質量%、好ましくは、0.05質量%~1質量%の範囲である。
本発明において「交差させた」とは、クロス型電波吸収体3が載置される磁性吸収体板2に対して平行な断面において、少なくともその一部で二つ以上の誘電損失材料が交差している構造を有することを言う。クロス型電波吸収体3が、磁性吸収体板2に対して平行な断面で見て、誘電損失体板33が交差した構造を有せば、特にその製法は限定されない。例えば、折り曲げた2枚の誘電損失体板を張り合わせることによっても形成される。また、クロス型電波吸収体3は磁性吸収体板2上に直接設置されるのが好ましい。しかし、磁性吸収体の特性に支障を及ぼさない範囲で磁性吸収体板とクロス型電波吸収体との間に適宜中間層を設置することもできる。
電波吸収体の吸収性能を向上させるためには、電波吸収体の先端から底面にかけて、垂直方向の誘電率変化を小さくして、電波吸収体表面での反射を出来るだけ小さくすることが有効である。そのため、クロス型電波吸収体の先端角度θを出来る限り小さい鋭角にして、導電性材料の濃度勾配を緩やかにする必要がある。具体的には、クロス型電波吸収体の先端角度θは、1°~45°が好ましく、5°~30°がより好ましい(図2(A)参照)。
電波暗室のサイズを大きく設定するには限界があり、例えば、EMC評価用で広く用いられている10m法電波暗室の一般的な暗室サイズは15m×24m×9m(高さ)である。また、電波暗室に設置される電波吸収体の底面積はコストや施工性を考慮して決められ、一般には、一辺が600mm程度に設定されている。このような条件下で、電波吸収特性に優れ、且つ測定有効空間の広い電波暗室を設計するためには、電波吸収体の高さは600mm~2000mmに設定するのが好ましい。電波暗室の要求性能によって、クロス型電波吸収体の高さと先端角度θは適宜調整される。
ここで、低誘電率層11の垂直方向の厚み(図4のhに相当する)をt11(mm)、電波吸収層12及び13の誘電率をε12、ε13、電波吸収層12及び13の垂直方向の厚みをt12(mm)、t13(mm)とする。低誘電率層11及び電波吸収層12、13は磁性吸収体板2による低周波帯域での電波吸収性能を充分に発揮でき、且つ低周波帯域から高周波帯域までの広い周波数帯域に渡って優れた電波吸収性能を得ることが出来る特性値にする必要がある。同量のカーボンが含まれる電波吸収層は、厚みが薄いと見た目上の誘電率は高くなり、厚みが厚いと見た目上の誘電率は低くなる。この特性を利用し、電波吸収層12、13のそれぞれの特性値の範囲は、それぞれの誘電率(ε12、ε13)と厚み(t12、t13)の積(ε12×t12、ε13×t13)によって規定することが出来る。具体的には、誘電率と厚み(mm)の積が10~40であることが好ましく、20~35であることがより好ましい。また低誘電率層11の厚みt11(mm)は、電波吸収層12、13の特性値によって変化する。具体的には、10mm~500mmに設定することが好ましく、電波吸収層12、13の特性値が上限に近い場合は、電波吸収層12、13自身で充分に電波を吸収することができるため、t11(mm)は下限近くでも充分な吸収性能を得ることが出来る。電波吸収層12、13の特性値が下限に近い場合は、電波吸収層12、13自身の電波吸収性能が低いため、充分な吸収性能を得るためにt11(mm)は上限近くに設定することがより好ましい。
電波吸収層間に、電波吸収層より誘電率が低くなるように気体又は固体を充填した低誘電率層を介在させることにより、本発明の効果は得られる。低誘電率層の誘電率は3以下であるのが好ましく、誘電率及びコストを考慮すると空気層(空間層)であるのがより好ましい。
図1に示すように誘電損失体板に区切られる4カ所の空間に配置される斜板構造の小型電波吸収体4はそれぞれ異なる向きに配置するのが好ましい。このような構造にすることにより、偏波依存性がなく、様々な角度から到来する電磁波を効果的に吸収することができる。
例えば、図6(A)の複合型電波吸収体は、上側から見ると、一見従来の複合型電波吸収体との違いは認められない。しかし、その小型電波吸収体4を垂直な断面で見ると低誘電率層を介した2枚の斜板で構成されている。これにより複層の斜板構造の小型電波吸収体と同様にピラミッド型の複数の吸収層による電磁波の減衰効果と位相差による電磁波の打ち消し効果との相乗効果が得られる。図6(A)では誘電損失体板に区切られる1空間毎に4個のピラミッド構造体が配置されているが、ピラミッド構造体の個数は複合型電波吸収体全体の大きさや要求性能に応じて適宜変更することもできる。また、図6(A)では、ピラミッド構造体の下に正四角筒の構造体が配置されているが、ピラミッド構造体を磁性吸収体板上に直接設置することもできる。例えば図6(C)に示すように異なるサイズのピラミッド形状のものを二つ重ねたピラミッド構造体を磁性吸収体板上に直接設置したもの(低誘電率層の厚さが一定)、また図6(D)に示すような異なる傾斜のピラミッド形状のものを二つ重ねたピラミッド構造体を磁性吸収体板上に直接設置したもの(低誘電率層の厚さが変化)が挙げられる。くさび形状の場合については図示していないが、ピラミッド断面の左右半分の形状をその断面形状とするくさび形状が例として挙げられる。
なお、本発明においては、隣接するピラミッドの谷間部に到来する波長の短い高周波数帯域の電磁波も有効に吸収するためには、図6(A)に示すように正四角筒の構造体を配置するのが好ましい。また、上部から見て、磁性吸収体板が覆い隠されるように小型電波吸収体が配置されることが好ましい。
導電材料の含有率は導電材料の種類や形態等により異なる。例えば、グラファイトの様な粉末状のカーボンであれば、誘電損失材料の全質量に対して、1.7質量%~7質量%が好ましく、カーボンファイバーの様な繊維状のカーボンであれば、0.03質量%~1.7質量%が好ましく、0.03質量%~0.4質量%がより好ましい。なお、繊維状のカーボンを用いる場合には、その繊維長が0.5mm~7mmであることが好ましく、この場合に最適な導電性が得る。
難燃剤は、誘電損失板や導電性シート等電波吸収体の構成材料に適用できるものであれば、特に限定されないが、ホウ酸系やリン酸系の難燃剤が好ましい。ホウ酸系化合物としては、ホウ酸ナトリウム、ホウ酸カリウム、ホウ酸マグネシウム、ホウ酸ストロンチウム、ホウ酸亜鉛等公知の難燃剤が挙げられる。また、リン酸系化合物としては、リン酸ナトリウム、リン酸カリウム、リン酸カルシウム、リン酸亜鉛、ポリリン酸アンモニウム等公知の難燃剤が挙げられる。難燃剤の添加量は、各板材の質量に対して、固形分量で5~50質量%であるのが好ましく、10~30質量%であるのがより好ましい。
紙製の非導電性シートからなる厚み15mmのハニカム構造体を、底面部(下辺)600mm、先端部(上辺)100mm、高さ1400mmの台形状に切断した。この形状の板をクロス型電波吸収体の基礎部材として2枚作製した。2枚の基礎部材の表裏に、繊維長6mm、繊維径7μmのカーボンファイバーを混練した紙製の導電性シート(導電性シートのカーボン含有率:1質量%)を貼り合わせ、誘電損失体板とした。なお、誘電損失体板全体に占めるカーボンの含有率は、0.1質量%であった。得られた誘電損失体板の一方は、上部に切欠きを入れ、他方は下部に切欠きを入れた(図2(A)、2(B)参照)。それぞれの切欠き部同士を嵌め合わせることによってクロス型電波吸収体を形成した。このクロス型電波吸収体をフェライトタイル上に設置して、フェライトタイル上の誘電損失体板(クロス型電波吸収体)により、区切られた空間に以下の実施例1~4及び比較例1~3により作製した小型電波吸収体をそれぞれ設置して、複合型電波吸収体とした。
パルプ中にカーボンの含有率が1質量%となるように繊維長3mm、繊維径7μmのカーボンファイバーを分散させ、抄紙することにより導電性シートを作製した。この導電性シートを紙製の非導電性シートを中芯としてその表裏に貼り付けることによって、厚さ3mmの段ボールシートを作製し、300mm(幅)×1530mm(長さ)に切断した。なお、段ボールシート全体の質量に対するカーボン含有率は0.4質量%であった。得られた段ボールシートを図5に示す展開図に従って、aを600mm、bを150mm、dを30mmとして、折り曲げ、のりしろ部分(d)に接着剤をつけて付着することにより、空間層(低誘電率層)150mmを介した2層の電波吸収体層構造とした。この構造の小型電波吸収体を図1に示すようにクロス型電波吸収体で区切られた空間4カ所にそれぞれ異なる向きで斜めに配置して斜板構造とし、これを含む複合型電波吸収体を作製した。
実施例1と同様の段ボールシートを用いて、小型電波吸収体を作製した。ここで、図5に示す展開図のbを100mmとして、空間層(低誘電率層)を100mmとした他は全て実施例1と同様とした。
実施例1と同様の段ボールシートを用いて、図7(A)に示す展開図から中空の四角錐(ピラミッド形状)を複数個作製した。ここで、四角錐の底辺の長さeは、150mmとして、高さfは500mmとした。また、また、図7(B)に示す展開図から底辺eが150mm、高さgが100mmの正四角筒を複数個作製した。2つの四角錐と1つの正四角筒を用いて、図7(D)に示すように、一方の四角錐の底辺と他方の四角錐の底辺をそれぞれ正四角筒の上辺と下辺とで合わせた形状とし、この内部に100mmの空間層(低誘電率層)が形成されるように2層構造の電波吸収体とした。このようにして形成した電波吸収体をクロス型電波吸収体で区切られた空間4カ所にそれぞれ4個ずつ合計16個を配置し、複合型電波吸収体とした。
パルプ中にカーボンの含有率が20質量%となるように粒径4μmのグラファイト粉末分散させ、抄紙することにより導電性シートを作製した。この導電性シートを紙製の非導電性シートを中芯としてその表裏に貼り付けることによって、厚さ3mmの段ボールシートを作製した。なお、段ボールシート全体の質量に対するカーボン含有率は8質量%であった。得られた段ボールシートを用いて、実施例1と同様に2層構造の小型電波吸収体を作製し、実施例1と同様にフェライトタイル上に設置することにより、複合型電波吸収体を作製した。
電波吸収体を構成する導電性シート及びハニカム構造体に予め難燃剤を用いて難燃性を付与した以外は、実施例1と同様に複合型電波吸収体を作製した。用いた難燃剤としては、株式会社トラストライフ製ファイアレスBを用いた。導電性シートは、固形分濃度を25%に調整した難燃剤溶液を塗工機で塗布した後、100℃で1時間乾燥して不燃処理を行った。不燃処理後、導電性シートの質量に対して10%の難燃液固形分が含まれていた。一方、ハニカム構造体は、固形分濃度を25%とした難燃剤溶液を入れた含浸槽に所定時間含浸させた後、100℃で1時間乾燥して不燃処理を行った。不燃処理後、ハニカム構造体の質量に対して、13%の難燃液固形分が含まれていた。
実施例3と同様の段ボールシートを用いて、実施例3と同様に四角錐と正四角筒の吸収体を形成した。ここでは、1個の四角錐に1個の正四角筒を組み合わせて、単層構造の電波吸収体を作製した。得られた電波吸収体を実施例3と同様にクロス型電波吸収体で区切られた空間4カ所にそれぞれ4個ずつ合計16個を配置し、複合型電波吸収体とした。
パルプ中にカーボンの含有率が4質量%となるように繊維長3mm、繊維径7μmのカーボンファイバーを分散させ、抄紙することにより導電性シートを作製した。この導電性シートを紙製の非導電性シートを中芯としてその表裏に貼り付けることによって、厚さ3mmの段ボールシートを作製した。なお、段ボールシート全体の質量に対するカーボン含有率は1.6質量%であった。この段ボールシートを用いて、比較例1と同様に、1個の四角錐と1個の正四角筒とを組み合わせた形状の単層構造の電波吸収体を作製した。この電波吸収体を比較例1と同様にクロス型電波吸収体で区切られた空間4カ所にそれぞれ4個ずつ合計16個を配置し、複合型電波吸収体とした。
実施例3と同様の段ボールシートを用いて、実施例3と同様に四角錐と正四角筒を組み合わせた形状の電波吸収体を形成した。ここで、上下2段に重なった正四角筒の内部に密着2層構造のピラミッドが収まった2層構造電波吸収体とした。得られた電波吸収体を実施例3と同様にクロス型電波吸収体で区切られた空間4カ所にそれぞれ4個ずつ合計16個を配置し、複合型電波吸収体とした。
実施例1~4及び比較例1~3の複合型電波吸収体の電波吸収特性を測定した結果を表1に示す。ここで、電波吸収特性の評価は、30MHz~1GHzの低周波数側は、同軸管法により、1GHz~20GHzの高周波数側は、垂直入射法により行った。単層構造の比較例1では、高周波数帯域で充分な電波吸収特性を得られず、単層構造で、カーボン濃度を増加させた比較例2では、高周波数帯域の電波吸収特性は向上するが、低周波数帯域での電波吸収特性が低下した。また、比較例3のように電波吸収板を直接重ね合わせても高周波数帯域における電波吸収特性はあまり改善されなかった。一方、空間層(低誘電率層)を介した複数の電波吸収層を有する本発明の電波吸収体(実施例1~4)では、全て30MHz~18GHzにおいて20dB~40dBの良好な電波吸収特性を有していることが確認された。なお、表1には記載されていないが、全ての実施例において、20GHzにおいても良好な電波吸収特性が得られることが確認されている。
実施例5の電波吸収体の不燃性能を評価した結果を図8に示す。比較として、比較例1の電波吸収体について不燃性能を評価した結果も図8に示す。不燃性能評価は、建築基準法の「不燃材料」試験に定められているコーンカロリーメーターによる燃焼試験により行った。比較例1では、20分燃焼後の総発熱量が14.9MJ/m2であるのに対し、実施例5の電波吸収体では、4.7MJ/m2以下と難燃性が大幅に向上し、建築基準法の「不燃材料」に適合することが確認された。
2 磁性吸収体板
3 クロス型電波吸収体
4 小型電波吸収体
11 低誘電率層
12、13 電波吸収層
33 誘電損失体板
121、123 斜板
122 垂直板
Claims (3)
- 磁性吸収体板と、
前記磁性吸収体板に対して垂直に配置される複数の誘電損失体板を交差させたクロス型電波吸収体、及び
磁性吸収体板上の、前記クロス型電波吸収体の誘電損失体板に区切られた空間に設置される小型電波吸収体を備える複合型電波吸収体であって、
前記小型電波吸収体は、前記磁性吸収体板に対して垂直方向において、複数の電波吸収層と、前記電波吸収層間に介在し、電波吸収層より誘電率の低い低誘電率層を有することを特徴とする複合型電波吸収体。 - 前記低誘電率層の垂直方向の厚さが、10mm~500mmであることを特徴とする請求項1に記載の複合型電波吸収体。
- 前記小型電波吸収体の垂直方向の寸法が、200mm~700mmであることを特徴とする請求項1又は2に記載の複合型電波吸収体。
Priority Applications (4)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP2010508181A JP5496879B2 (ja) | 2008-04-15 | 2009-04-08 | 複合型電波吸収体 |
CN200980122606.XA CN102067744B (zh) | 2008-04-15 | 2009-04-08 | 复合型电波吸收体 |
EP09733457.7A EP2293661A4 (en) | 2008-04-15 | 2009-04-08 | COMPOSITE RADIO WAVE ABSORBER |
US13/002,227 US8466825B2 (en) | 2008-04-15 | 2009-04-08 | Combined electromagnetic wave absorber |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP2008-105656 | 2008-04-15 | ||
JP2008105656 | 2008-04-15 |
Publications (1)
Publication Number | Publication Date |
---|---|
WO2009128377A1 true WO2009128377A1 (ja) | 2009-10-22 |
Family
ID=41199074
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/JP2009/057211 WO2009128377A1 (ja) | 2008-04-15 | 2009-04-08 | 複合型電波吸収体 |
Country Status (6)
Country | Link |
---|---|
US (1) | US8466825B2 (ja) |
EP (1) | EP2293661A4 (ja) |
JP (1) | JP5496879B2 (ja) |
CN (1) | CN102067744B (ja) |
TW (1) | TWI528636B (ja) |
WO (1) | WO2009128377A1 (ja) |
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPWO2014088019A1 (ja) * | 2012-12-05 | 2017-01-05 | 東レ株式会社 | 電波吸収体部材用難燃紙及び電波吸収体部材 |
JPWO2021020110A1 (ja) * | 2019-08-01 | 2021-02-04 |
Families Citing this family (10)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP5731548B2 (ja) * | 2011-02-03 | 2015-06-10 | 株式会社ニレコ | 帯状体の幅方向端部位置測定装置及び帯状体の幅方向中心位置測定装置 |
RU2497245C1 (ru) * | 2012-02-27 | 2013-10-27 | Федеральное государственное бюджетное образовательное учреждение высшего профессионального образования "Самарский государственный университет" | Малоотражающее покрытие на основе омега-частиц и способ его изготовления |
US9606158B2 (en) * | 2013-08-02 | 2017-03-28 | Rohde & Schwarz Gmbh & Co. Kg | Slotline antenna |
JP6103249B2 (ja) * | 2014-05-20 | 2017-03-29 | Tdk株式会社 | 電波吸収体及び電波暗室 |
JP6441756B2 (ja) * | 2015-07-10 | 2018-12-19 | 株式会社トーキン | 難燃性複合磁性体 |
CN108997711B (zh) * | 2017-06-07 | 2023-04-07 | 洛阳尖端技术研究院 | 一种吸波浸渍胶液和吸波蜂窝及其制备方法 |
WO2019175717A1 (en) | 2018-03-14 | 2019-09-19 | Desiccant Rotors International Private Limited | Method for in-situ synthesis of metal organic frameworks (mofs), covalent organic frameworks (cofs) and zeolite imidazolate frameworks (zifs), and applications thereof |
JP2019186507A (ja) * | 2018-03-30 | 2019-10-24 | デュポン帝人アドバンスドペーパー株式会社 | 電磁波吸収シート、およびその製造方法 |
CN112909571B (zh) * | 2021-02-06 | 2022-06-03 | 中北大学 | 一种兼具多种类型超材料优势的组合吸波复合材料 |
US11609254B2 (en) * | 2021-08-11 | 2023-03-21 | Apple Inc. | Electromagnetic shielded testing chamber with ventilation |
Citations (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPS6240798A (ja) * | 1985-08-17 | 1987-02-21 | 日東紡績株式会社 | 抵抗皮膜並列型電波吸収体素子 |
JPH08274491A (ja) * | 1995-03-29 | 1996-10-18 | Tech Res & Dev Inst Of Japan Def Agency | 電波吸収体 |
JP2001127483A (ja) | 1999-10-28 | 2001-05-11 | Riken Corp | 電波吸収体 |
JP2004253760A (ja) * | 2002-12-25 | 2004-09-09 | Toray Ind Inc | 電波吸収体用シート材および電波吸収体 |
JP2007067395A (ja) * | 2005-08-05 | 2007-03-15 | Tdk Corp | 電波吸収体及びその製造方法、並びに電波暗室 |
Family Cites Families (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
BE540736A (ja) * | 1953-03-28 | |||
US4038660A (en) * | 1975-08-05 | 1977-07-26 | The United States Of America As Represented By The Secretary Of The Army | Microwave absorbers |
JPH0479300A (ja) * | 1990-07-23 | 1992-03-12 | Akzo Kashima Ltd | 電波吸収体 |
CN100484384C (zh) * | 2002-12-25 | 2009-04-29 | 东丽株式会社 | 电波吸收体用板材及电波吸收体 |
US7479917B2 (en) * | 2005-08-05 | 2009-01-20 | Tdk Corporation | Electromagnetic wave absorber, manufacturing method thereof and electromagnetic wave anechoic room |
-
2009
- 2009-04-08 EP EP09733457.7A patent/EP2293661A4/en not_active Withdrawn
- 2009-04-08 JP JP2010508181A patent/JP5496879B2/ja not_active Expired - Fee Related
- 2009-04-08 CN CN200980122606.XA patent/CN102067744B/zh not_active Expired - Fee Related
- 2009-04-08 WO PCT/JP2009/057211 patent/WO2009128377A1/ja active Application Filing
- 2009-04-08 US US13/002,227 patent/US8466825B2/en not_active Expired - Fee Related
- 2009-04-14 TW TW098112324A patent/TWI528636B/zh not_active IP Right Cessation
Patent Citations (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPS6240798A (ja) * | 1985-08-17 | 1987-02-21 | 日東紡績株式会社 | 抵抗皮膜並列型電波吸収体素子 |
JPH08274491A (ja) * | 1995-03-29 | 1996-10-18 | Tech Res & Dev Inst Of Japan Def Agency | 電波吸収体 |
JP2001127483A (ja) | 1999-10-28 | 2001-05-11 | Riken Corp | 電波吸収体 |
JP2004253760A (ja) * | 2002-12-25 | 2004-09-09 | Toray Ind Inc | 電波吸収体用シート材および電波吸収体 |
JP2007067395A (ja) * | 2005-08-05 | 2007-03-15 | Tdk Corp | 電波吸収体及びその製造方法、並びに電波暗室 |
Non-Patent Citations (1)
Title |
---|
See also references of EP2293661A4 |
Cited By (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPWO2014088019A1 (ja) * | 2012-12-05 | 2017-01-05 | 東レ株式会社 | 電波吸収体部材用難燃紙及び電波吸収体部材 |
JPWO2021020110A1 (ja) * | 2019-08-01 | 2021-02-04 | ||
JP7386406B2 (ja) | 2019-08-01 | 2023-11-27 | パナソニックIpマネジメント株式会社 | 電磁波可視化装置 |
Also Published As
Publication number | Publication date |
---|---|
TWI528636B (zh) | 2016-04-01 |
CN102067744A (zh) | 2011-05-18 |
US20110227775A1 (en) | 2011-09-22 |
EP2293661A1 (en) | 2011-03-09 |
EP2293661A4 (en) | 2015-06-10 |
JPWO2009128377A1 (ja) | 2011-08-04 |
CN102067744B (zh) | 2014-07-23 |
JP5496879B2 (ja) | 2014-05-21 |
US8466825B2 (en) | 2013-06-18 |
TW200947803A (en) | 2009-11-16 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
JP5496879B2 (ja) | 複合型電波吸収体 | |
JP4346360B2 (ja) | 電波吸収体用シート材および電波吸収体 | |
US6359581B2 (en) | Electromagnetic wave abosrber | |
JP3030453B2 (ja) | 広帯域電波吸収体 | |
CN103547134A (zh) | 电磁波吸收体 | |
WO2011016109A1 (ja) | 電波吸収体 | |
JP4684699B2 (ja) | 電波吸収シート材およびそれを用いた電波吸収体 | |
CN100484384C (zh) | 电波吸收体用板材及电波吸收体 | |
JP4314831B2 (ja) | 電波吸収体 | |
JP6103249B2 (ja) | 電波吸収体及び電波暗室 | |
JP2012191183A (ja) | 電波吸収体用シート材及び電波吸収体 | |
WO2010119863A1 (ja) | 電波吸収体 | |
JP2001244686A (ja) | 電波吸収体、電波暗箱、電波暗室、電波吸収パネルおよび電波吸収衝立 | |
JP2016146374A (ja) | 電波吸収体 | |
JP6519317B2 (ja) | 電波吸収体 | |
JP2005012031A (ja) | 電波吸収体 | |
JP5953798B2 (ja) | 電波吸収体用シート材及び電波吸収体 | |
JP5953799B2 (ja) | 電波吸収体用シート材及び電波吸収体 | |
JP5221178B2 (ja) | 電波吸収体 | |
JP4338460B2 (ja) | 電波吸収体およびその製造方法 | |
JP4422980B2 (ja) | 電波吸収体 | |
JPH10135682A (ja) | 多層電波吸収体 | |
RU2253927C1 (ru) | Сверхширокодиапазонное радиопоглощающее устройство | |
JPH09275295A (ja) | 電波吸収体 | |
JP2021170614A (ja) | 耐電力電波吸収体 |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
WWE | Wipo information: entry into national phase |
Ref document number: 200980122606.X Country of ref document: CN |
|
121 | Ep: the epo has been informed by wipo that ep was designated in this application |
Ref document number: 09733457 Country of ref document: EP Kind code of ref document: A1 |
|
NENP | Non-entry into the national phase |
Ref country code: DE |
|
WWE | Wipo information: entry into national phase |
Ref document number: 2010508181 Country of ref document: JP |
|
REEP | Request for entry into the european phase |
Ref document number: 2009733457 Country of ref document: EP |
|
WWE | Wipo information: entry into national phase |
Ref document number: 2009733457 Country of ref document: EP |
|
WWE | Wipo information: entry into national phase |
Ref document number: 13002227 Country of ref document: US |