JP2004214231A - Transmissive radio wave absorption equipment - Google Patents

Transmissive radio wave absorption equipment Download PDF

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JP2004214231A
JP2004214231A JP2002378551A JP2002378551A JP2004214231A JP 2004214231 A JP2004214231 A JP 2004214231A JP 2002378551 A JP2002378551 A JP 2002378551A JP 2002378551 A JP2002378551 A JP 2002378551A JP 2004214231 A JP2004214231 A JP 2004214231A
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radio wave
layer
wave absorption
impedance
incident
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JP4115829B2 (en
Inventor
Takashi Nakamura
隆 中村
Tatsunari Deguchi
竜成 出口
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TEKKU C KK
Sankyo Co Ltd
C Tech Corp
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TEKKU C KK
Sankyo Co Ltd
C Tech Corp
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Abstract

<P>PROBLEM TO BE SOLVED: To provide transmissive radio wave absorption equipment which prevents reflected waves with respect to the incident angle of a wide range in the incident wave. <P>SOLUTION: In a plurality of laminated radio wave absorption layers, a dielectric layer is arranged on the incident side of a radio wave, and an impedance layer on a transmission-side. A specific dielectric constant of the dielectric layer arranged in the radio wave absorption layer installed in a pre-stage of the incident side of the radio wave rather than the prescribed radio wave absorption layer is smaller than that of the dielectric layer disposed in the prescribed radio wave absorption layer. When the wavelength of the incident radio wave is set to be λ<SB>0</SB>, the specific dielectric constant of the dielectric layer in the respective radio wave absorption layers to be ε<SB>r</SB>and peculiar impedance in regions on the incident side, and a transmission-side to be Z<SB>0</SB>; thickness (d) of the dielectric layers and impedance Z<SB>s</SB>of the respective impedance layers are calculated by d=λ<SB>0</SB>/[4(<SB>εr</SB>)<SP>1/2</SP>] and Z<SB>s</SB>=Z<SB>0</SB>/(ε<SB>r</SB>-Z<SB>0</SB>/Z<SB>3</SB>). <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

【０００１】
【発明の属する技術分野】
本発明は、電波を透過及び吸収させることによって電波の反射波の影響を防止する透過型電波吸収装置に関する。
【０００２】
【従来の技術】
電波送信装置から送信される電波は、直接波として受信装置で受信されるだけでなく、例えば、コンクリート壁等の反射体で反射した反射波も受信装置で受信される。受信装置で直接波及び反射波が受信されると、受信障害等が発生する。
そのため、電波の反射を防止する電波吸収体が開発されている。電波吸収体では、一般的に、入射波に対して反射波と透過波がないことを基本としてきた。しかしながら、透過波を許容することにより、電波吸収体を構成する要素の材料や形状等の選択の自由度を増加させることができる（例えば、特許文献１参照）。
【０００３】
透過波を許容した従来の透過型電波吸収体の、周波数特性を図４に示す。このように、入射波の波長にあわせた種々の電波吸収体を構成することができる。このうち、約５．８ＧＨｚで吸収減衰量が最大となる電波吸収体の角度特性を図５に示す。この電波吸収体は、例えば、電波の入射側から、誘電体層、インピーダンス層が設けられていて、誘電体層の比誘電率εrは、６．７、誘電体層の厚さｄ＝５．０ｍｍ、そして、インピーダンス層のインピーダンスＺs＝６６Ωである。図５に示す角度特性では、横軸が入射波の角度θ［ｄｅｇ］、縦軸が反射電力係数Γ［ｄＢ］、透過電力係数Ｔ［ｄＢ］を示す。図５に角度特性を示す従来の電波吸収体では、電波の入射角度０度付近の吸収減衰量は良好であるが、入射角度が大きくなると極端に吸収減衰量が減少する。
一般的に、電波吸収体は、反射電力係数Γが−２０ｄＢ以上の状態において電波吸収体として実際に用いることができる。つまり、この電波吸収体では、入射波の入射角の範囲が±３５度程度まで電波吸収性能を発揮することができる。
【０００４】
【特許文献１】特願２００１−１９５２２５
【０００５】
【発明が解決しようとする課題】
しかしながら、電波吸収体を用いる上で、一層、入射波に対して広角度特性が要求される場合もある。例えば、ＥＴＣで用いられる電波吸収体では、入射波の入射角±４５度で−２５ｄＢ程度の吸収減衰量が必要とされている。
そこで、本発明は、入射波の広範囲の入射角に対して反射波の発生を防止する透過型電波吸収装置を提供することを目的とする。
【０００６】
【課題を解決するための手段】
前記課題を解決するための本発明の第１〜第３発明は、請求項１〜３に記載されたとおりの透過型電波吸収装置である。
請求項１に記載の透過型電波吸収装置は、複数種類の透過型電波吸収層により構成され、各透過型電波吸収層は誘電体層とインピーダンス層とを備えている。
請求項２に記載の透過型電波吸収装置は、各電波吸収層は、電波の入射側に誘電体層が、透過側にインピーダンス層が設けられ、各電波吸収層は、積層された状態で配設され、所定の電波吸収層よりも電波の入射側前段に配設された電波吸収層に設けられている誘電体層の比誘電率は、所定の電波吸収層に設けられている誘電体層の比誘電率よりも小さい。
請求項３に記載の透過型電波吸収装置は、各電波吸収層では、入射電波の波長をλ0、各電波吸収層の誘電体層の比誘電率をεr、入射側及び透過側の領域の固有インピーダンスをＺ0としたときに、各誘電体層の厚さｄ、及び各インピーダンス層のインピーダンスＺsを、
【数１】

Figure 2004214231
で算出可能である。
請求項４に記載の透過型電波吸収装置は、周波数５．８ＧＨｚ程度の電波の入射角度が約４５度の時に、電波の吸収減衰量が−２０ｄＢ以上である。
請求項１〜４に記載の透過型電波吸収装置を用いれば、入射波の広範囲の入射角に対して反射波の発生を防止することができる。
【０００７】
【発明の実施の形態】
以下に本発明の実施の形態を図面を用いて説明する。
本発明の透過型電波吸収装置で用いる透過型電波吸収体の一実施の形態の概略図を図１に示す。本実施の形態の透過型電波吸収装置１は、電波の入射側から順に、第１の電波吸収層（第１の誘電体層１０、第１のインピーダンス層１１）、第２の電波吸収層（第２の誘電体層２０、第２のインピーダンス層２１）が積層された状態で設けられていている。
第１の誘電体層１０は、例えば、比誘電率εr1が２．３のポリプロピレンで構成されている。第２の誘電体層２０は、例えば、比誘電率εr2が６．７のガラスで構成されている。第１、第２のインピーダンス層１１、２１は、例えば、スズ、亜鉛等の抵抗体を各誘電体層１０、２０に貼着あるいは塗布することによって薄膜状に形成したものである。
【０００８】
ところで、図２に示すような、領域Ａ（例えば、自由空間等）と領域Ｂ（例えば、自由空間等）の間に設けられた単層の透過型電波吸収体では、入射波の波長λ0と、電波吸収体を構成する誘電体の比誘電率εrより、誘電体層の厚さｄとインピーダンス層のインピーダンスＺsは下記のようにして算出することができる。領域Ａ、領域Ｂの固有インピーダンスをＺ0とする。
透過型電波吸収体の反射波を零にするためには、Ｑマッチセクションの原理を応用する。そこで、式（１）に示すように誘電体層の厚さｄを、入射波の波長（誘電体層内における波長λm）の４分の１とする。これにより、誘電体層の表面で反射した反射波と、誘電体層に入射してインピーダンス層の表面で反射した反射波の位相は２分の１波長（１８０度）のずれが生ずる。このため、両方の反射波が相殺され、トータルとして反射波は零となる。また、この際のインピーダンス層のインピーダンスは、式（２）で表される。
【数２】
Figure 2004214231
Figure 2004214231
【数３】
Figure 2004214231
Figure 2004214231
【０００９】
ここで、図１に示す、本発明の透過型電波吸収装置１のように、透過型電波吸収層が２層である場合について説明する。
まず、第２の電波吸収層（第２の誘電体層２０、第２のインピーダンス層２１）のみについて説明する。入射波の波長λ0、第２の誘電体層の比誘電率εr2より、第２の誘電体層の厚さｄ2と第２のインピーダンス層２１のインピーダンスＺs2は下記のようにして算出することができる。
【数４】
Figure 2004214231
Figure 2004214231
次に、第１の電波吸収層（第１の誘電体層１０、第１のインピーダンス層１１）について説明する。第２の電波吸収層では、前述した式（３）の条件を満たすように第２の誘電体層の厚さｄ2と第２のインピーダンス層２１のインピーダンスＺs2を決定すれば、反射波は零であるので、第２の電波吸収層があることで第１の電波吸収層に及ぼす影響は誤差の範囲内である。このため、第１の電波吸収層についても、第１の電波吸収層のみについて考慮すればよい。よって、入射波の波長λ0、第１の誘電体層の比誘電率εr1より、誘電体層の厚さｄ1と第１のインピーダンス層１１のインピーダンスＺs1は下記のようにして算出することができる。
【数５】
Figure 2004214231
Figure 2004214231
【００１０】
これによれば、第１の誘電体層１０の比誘電率εr1を２．３とすると、５．８ＧＨｚの入射波の場合、第１の誘電体層１０の厚さは、式（４）より、ｄ1＝９．２ｍｍ、そして、第１のインピーダンス層１１では、インピーダンスＺs1＝２９２Ωという値を算出することができる。
また、第２の誘電体層２０の比誘電率εr2を６．７とすると、５．８ＧＨｚの入射波の場合、第２の誘電体層２０の厚さは、式（３）より、ｄ2＝５．０ｍｍ、そして、第２のインピーダンス層２１では、インピーダンスＺs2＝６６Ωという値を算出することができる。
【００１１】
このように第１の電波吸収層と、第２の電波吸収層を、図１に示すように積層させた透過型電波吸収装置１は、入射波の波長λ0が約５．８ＧＨｚの場合、図３に示すような角度特性を示す。図３に示す角度特性では、横軸が入射波の角度θ［ｄｅｇ］、縦軸が反射電力係数Γ［ｄＢ］、透過電力係数Ｔ［ｄＢ］を示す。また、図３の実線は入射波のＴＥ波（入射面に電界が垂直で磁界が平行な入射波）、一点鎖線は入射波のＴＭ波（入射面に電界が垂直で磁界が平行な入射波）を示す。
一般的に、電波吸収体は、反射電力係数Γが−２０ｄＢ以上の状態において電波吸収体として実際に用いることができる。つまり、透過型電波吸収装置１では、入射波の波長λ0が約５．８ＧＨｚの場合、入射波の入射角の範囲が±５０度程度まで電波吸収性能を発揮することができる。
【００１２】
本実施の形態では、第１及び第２の電波吸収層を備え、各電波吸収層は、電波の入射側の前段に誘電体層を、後段にインピーダンス層を備え、第２の電波吸収層よりも電波の入射側の前段に第１の電波吸収層が設けられている。第１の電波吸収層が備えている第１の誘電体層１０の比誘電率εr1は、第２の電波吸収層が備えている第２の誘電体層２０の比誘電率εr2よりも小さい。このように、透過型電波吸収装置１を構成することにより、入射波の広範囲の入射角に対して反射波の発生を防止することができる。
また、このように多層にしても、各透過型電波吸収層に関して独立して誘電体層の厚さとインピーダンス層のインピーダンスを算出することができるので、製作が容易である。
【００１３】
本発明は、実施の形態で説明した構成に限定されることなく、種々の変更、追加、削除が可能である。
例えば、インピーダンス層として抵抗体の薄膜を用いた場合について説明したが、インピーダンス層は抵抗薄膜に限定されない。
また、磁性を有しない誘電体層について説明したが、磁性を有する誘電体層を用いることもできる。
誘電体層の損失を考慮しなかったが、誘電体層として損失性誘電体層を用いることもできる。
また、本実施の形態では、透過型電波吸収層が２層の場合について説明したが、透過型電波吸収層は３層以上でもよい。電波の入射側前段に設けられた透過型電波吸収層の誘電体層の比誘電率が、１層後段の透過型電波吸収層の誘電体層の比誘電率より小さければよい。
本実施の形態では、第１の誘電体層１０がポリプロピレン、第２の誘電体層２０がガラスの場合について説明したが、各誘電体は他の材料でもよい。
【００１４】
【発明の効果】
以上説明したように、請求項１〜４に記載の透過型電波吸収装置を用いれば、入射波の広範囲の入射角に対して反射波の発生を防止することができる。
【図面の簡単な説明】
【図１】本発明の透過型電波吸収装置１の一実施の形態の概略構成図である。
【図２】透過型電波吸収体の原理を説明する図である。
【図３】透過型電波吸収装置１の角度特性を示す図である。
【図４】従来の電波吸収体を示す図である。
【図５】従来の電波吸収体を示す図である。
【符号の説明】
１ 透過型電波吸収装置
１０ 第１の誘電体層
１１ 第１のインピーダンス層
２０ 第２の誘電体層
２１ 第２のインピーダンス層[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a transmission-type radio wave absorber that transmits and absorbs radio waves to prevent the influence of reflected waves of the radio waves.
[0002]
[Prior art]
The radio wave transmitted from the radio wave transmitting device is not only received by the receiving device as a direct wave, but also the reflected wave reflected by a reflector such as a concrete wall is received by the receiving device. When a direct wave and a reflected wave are received by the receiving device, a reception failure or the like occurs.
Therefore, a radio wave absorber for preventing reflection of radio waves has been developed. In general, a radio wave absorber has basically been based on the absence of a reflected wave and a transmitted wave with respect to an incident wave. However, by allowing transmitted waves, it is possible to increase the degree of freedom in selecting materials, shapes, and the like of elements constituting the radio wave absorber (for example, see Patent Document 1).
[0003]
FIG. 4 shows the frequency characteristics of a conventional transmission type radio wave absorber that allows transmission waves. Thus, various radio wave absorbers can be configured according to the wavelength of the incident wave. FIG. 5 shows the angular characteristics of the radio wave absorber having the maximum absorption attenuation at about 5.8 GHz. This radio wave absorber is provided with, for example, a dielectric layer and an impedance layer from the radio wave incident side. The dielectric layer has a relative permittivity ε r of 6.7 and a thickness d = 5 of the dielectric layer. 0.0 mm, and the impedance of the impedance layer Z s = 66Ω. In the angle characteristics shown in FIG. 5, the horizontal axis indicates the angle θ [deg] of the incident wave, and the vertical axis indicates the reflected power coefficient Γ [dB] and the transmitted power coefficient T [dB]. In the conventional radio wave absorber whose angle characteristic is shown in FIG. 5, the absorption attenuation amount near the incident angle of 0 degrees of the radio wave is good, but the absorption attenuation amount decreases extremely as the incident angle increases.
Generally, a radio wave absorber can be actually used as a radio wave absorber when the reflected power coefficient Γ is -20 dB or more. That is, this radio wave absorber can exhibit radio wave absorption performance up to an incident angle range of about ± 35 degrees of the incident wave.
[0004]
[Patent Document 1] Japanese Patent Application No. 2001-195225
[0005]
[Problems to be solved by the invention]
However, when using the radio wave absorber, there may be a case where a wider angle characteristic is required for the incident wave. For example, a radio wave absorber used in ETC requires an absorption attenuation of about -25 dB at an incident angle of an incident wave of ± 45 degrees.
SUMMARY OF THE INVENTION It is an object of the present invention to provide a transmission type radio wave absorber that prevents generation of a reflected wave at a wide range of incident angles of an incident wave.
[0006]
[Means for Solving the Problems]
The first to third inventions of the present invention for solving the above-mentioned problems are transmission-type radio wave absorbers as described in claims 1 to 3.
The transmission type radio wave absorption device according to the first aspect includes a plurality of types of transmission type radio wave absorption layers, each of which includes a dielectric layer and an impedance layer.
In the transmission type radio wave absorption device according to the present invention, each radio wave absorption layer is provided with a dielectric layer on a radio wave incident side and an impedance layer on a transmission side, and each radio wave absorption layer is arranged in a stacked state. The relative permittivity of the dielectric layer provided on the radio wave absorbing layer disposed on the front side of the radio wave incident side with respect to the predetermined radio wave absorbing layer is the dielectric layer provided on the predetermined radio wave absorbing layer. Is smaller than the relative permittivity of
The transmission-type radio wave absorber according to claim 3, wherein in each radio wave absorption layer, the wavelength of the incident radio wave is λ 0 , the relative permittivity of the dielectric layer of each radio wave absorption layer is ε r , and the area on the incident side and the transmission side. Is defined as Z 0 , the thickness d of each dielectric layer, and the impedance Z s of each impedance layer,
(Equation 1)
Figure 2004214231
Can be calculated.
In the transmission type radio wave absorber according to claim 4, when the incident angle of the radio wave having a frequency of about 5.8 GHz is about 45 degrees, the attenuation of the radio wave absorption is -20 dB or more.
The use of the transmission-type radio wave absorber according to claims 1 to 4 makes it possible to prevent the generation of a reflected wave at a wide range of incident angles of the incident wave.
[0007]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a schematic view of an embodiment of a transmission type radio wave absorber used in the transmission type radio wave absorption device of the present invention. The transmission-type radio wave absorber 1 according to the present embodiment includes a first radio wave absorption layer (first dielectric layer 10, first impedance layer 11) and a second radio wave absorption layer ( The second dielectric layer 20 and the second impedance layer 21) are provided in a stacked state.
The first dielectric layer 10 is made of, for example, polypropylene having a relative dielectric constant ε r1 of 2.3. The second dielectric layer 20 is made of, for example, glass having a relative dielectric constant ε r2 of 6.7. The first and second impedance layers 11 and 21 are formed in a thin film shape by, for example, sticking or applying a resistor such as tin or zinc to each of the dielectric layers 10 and 20.
[0008]
By the way, as shown in FIG. 2, in a single-layer transmission-type radio wave absorber provided between a region A (for example, free space) and a region B (for example, free space), the wavelength λ 0 of the incident wave is used. If, from the relative dielectric constant epsilon r of the dielectric material of the electromagnetic wave absorber, the impedance Z s of the thickness of the dielectric layer d and the impedance layer can be calculated as follows. The specific impedance of the region A and the region B is assumed to be Z 0 .
In order to make the reflected wave of the transmission type radio wave absorber zero, the principle of the Q match section is applied. Therefore, as shown in the equation (1), the thickness d of the dielectric layer is set to ４ of the wavelength of the incident wave (wavelength λ m in the dielectric layer). As a result, the phase of the reflected wave reflected on the surface of the dielectric layer and the phase of the reflected wave incident on the dielectric layer and reflected on the surface of the impedance layer are shifted by a half wavelength (180 degrees). For this reason, both reflected waves cancel each other out, and the total number of reflected waves becomes zero. In this case, the impedance of the impedance layer is expressed by Expression (2).
(Equation 2)
Figure 2004214231
Figure 2004214231
[Equation 3]
Figure 2004214231
Figure 2004214231
[0009]
Here, a case will be described in which there are two transmission-type radio wave absorbing layers as in the transmission type radio-wave absorption device 1 of the present invention shown in FIG.
First, only the second radio wave absorption layer (the second dielectric layer 20 and the second impedance layer 21) will be described. From the wavelength λ 0 of the incident wave and the relative dielectric constant ε r2 of the second dielectric layer, the thickness d 2 of the second dielectric layer and the impedance Z s2 of the second impedance layer 21 are calculated as follows. can do.
(Equation 4)
Figure 2004214231
Figure 2004214231
Next, the first radio wave absorption layer (the first dielectric layer 10 and the first impedance layer 11) will be described. In the second electromagnetic wave absorbing layer, if the thickness d 2 of the second dielectric layer and the impedance Z s2 of the second impedance layer 21 are determined so as to satisfy the above-described equation (3), the reflected wave will Since it is zero, the effect of the presence of the second radio wave absorbing layer on the first radio wave absorbing layer is within the range of the error. For this reason, only the first radio wave absorption layer needs to be considered for the first radio wave absorption layer. Therefore, from the wavelength λ 0 of the incident wave and the relative dielectric constant ε r1 of the first dielectric layer, the thickness d 1 of the dielectric layer and the impedance Z s1 of the first impedance layer 11 are calculated as follows. be able to.
(Equation 5)
Figure 2004214231
Figure 2004214231
[0010]
According to this, assuming that the relative dielectric constant ε r1 of the first dielectric layer 10 is 2.3, in the case of an incident wave of 5.8 GHz, the thickness of the first dielectric layer 10 is given by the following equation (4). Accordingly, it is possible to calculate a value of d 1 = 9.2 mm and a value of the impedance Z s1 = 292 Ω in the first impedance layer 11.
Further, assuming that the relative permittivity ε r2 of the second dielectric layer 20 is 6.7, in the case of an incident wave of 5.8 GHz, the thickness of the second dielectric layer 20 is expressed by d according to Expression (3). 2 = 5.0 mm, and the second impedance layer 21 can calculate a value of impedance Z s2 = 66Ω.
[0011]
As described above, the transmission type radio wave absorption device 1 in which the first radio wave absorption layer and the second radio wave absorption layer are laminated as shown in FIG. 1 has a structure in which the wavelength λ 0 of the incident wave is about 5.8 GHz. An angle characteristic as shown in FIG. 3 is shown. In the angular characteristics shown in FIG. 3, the horizontal axis represents the angle θ [deg] of the incident wave, and the vertical axis represents the reflected power coefficient Γ [dB] and the transmitted power coefficient T [dB]. The solid line in FIG. 3 indicates the incident wave TE wave (an incident wave whose electric field is perpendicular to the incident surface and the magnetic field is parallel), and the one-dot chain line indicates the incident wave TM wave (the incident wave whose electric field is perpendicular to the incident surface and the magnetic field is parallel) ).
Generally, a radio wave absorber can be actually used as a radio wave absorber when the reflected power coefficient Γ is -20 dB or more. That is, when the wavelength λ 0 of the incident wave is about 5.8 GHz, the transmission type radio wave absorbing device 1 can exhibit the radio wave absorbing performance up to an incident angle range of about ± 50 degrees.
[0012]
In the present embodiment, first and second radio wave absorbing layers are provided, each of which has a dielectric layer at the front stage on the radio wave incident side and an impedance layer at the rear stage, and Also, a first radio wave absorbing layer is provided at a stage preceding the radio wave incident side. The relative permittivity ε r1 of the first dielectric layer 10 included in the first radio wave absorption layer is higher than the relative permittivity ε r2 of the second dielectric layer 20 included in the second radio wave absorption layer. small. By configuring the transmission type radio wave absorber 1 as described above, it is possible to prevent generation of a reflected wave with respect to a wide range of incident angles of the incident wave.
Further, even with such a multi-layer structure, the thickness of the dielectric layer and the impedance of the impedance layer can be calculated independently for each transmission-type radio wave absorption layer, so that manufacture is easy.
[0013]
The present invention is not limited to the configuration described in the embodiment, and various changes, additions, and deletions are possible.
For example, although the case where a resistor thin film is used as the impedance layer has been described, the impedance layer is not limited to the resistance thin film.
Further, the dielectric layer having no magnetism has been described, but a dielectric layer having magnetism can also be used.
Although the loss of the dielectric layer was not considered, a lossy dielectric layer can be used as the dielectric layer.
Further, in the present embodiment, a case has been described in which the number of transmission type radio wave absorption layers is two, but the number of transmission type radio wave absorption layers may be three or more. It is sufficient that the relative permittivity of the dielectric layer of the transmission type radio wave absorption layer provided in the preceding stage on the radio wave incident side is smaller than the relative permittivity of the dielectric layer of the transmission type radio wave absorption layer in the subsequent stage.
In this embodiment, the case where the first dielectric layer 10 is made of polypropylene and the second dielectric layer 20 is made of glass has been described, but each dielectric may be made of another material.
[0014]
【The invention's effect】
As described above, the use of the transmission-type radio wave absorber according to claims 1 to 4 can prevent the generation of a reflected wave at a wide range of incident angles of the incident wave.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram of an embodiment of a transmission type radio wave absorption device 1 of the present invention.
FIG. 2 is a diagram illustrating the principle of a transmission type radio wave absorber.
FIG. 3 is a diagram showing an angle characteristic of the transmission type radio wave absorber 1.
FIG. 4 is a diagram showing a conventional radio wave absorber.
FIG. 5 is a view showing a conventional radio wave absorber.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Transmission type radio wave absorber 10 First dielectric layer 11 First impedance layer 20 Second dielectric layer 21 Second impedance layer

Claims (4)

複数種類の透過型電波吸収層により構成され、
各透過型電波吸収層は誘電体層とインピーダンス層とを備える透過型電波吸収装置。It is composed of multiple types of transmission type radio wave absorption layers,
Each transmission type radio wave absorption layer is a transmission type radio wave absorption device including a dielectric layer and an impedance layer. 請求項１に記載の透過型電波吸装置であって、
各電波吸収層は、電波の入射側に誘電体層が、透過側にインピーダンス層が設けられ、
各電波吸収層は、積層された状態で配設され、
所定の電波吸収層よりも電波の入射側前段に配設された電波吸収層に設けられている誘電体層の比誘電率は、所定の電波吸収層に設けられている誘電体層の比誘電率よりも小さいことを特徴とする透過型電波吸収装置。The transmission-type radio wave absorber according to claim 1,
Each radio wave absorption layer has a dielectric layer on the radio wave incident side and an impedance layer on the transmission side,
Each radio wave absorption layer is arranged in a stacked state,
The relative permittivity of the dielectric layer provided in the radio wave absorption layer disposed in front of the predetermined radio wave absorption layer on the radio wave incident side is the relative dielectric constant of the dielectric layer provided in the predetermined radio wave absorption layer. A transmission type radio wave absorption device characterized by being smaller than the ratio. 請求項２に記載の透過型電波吸装置であって、
各電波吸収層では、入射電波の波長をλ0、各電波吸収層の誘電体層の比誘電率をεr、入射側及び透過側の領域の固有インピーダンスをＺ0としたときに、各誘電体層の厚さｄ、及び各インピーダンス層のインピーダンスＺsを、
Figure 2004214231
で算出可能な透過型電波吸収装置。The transmission-type radio wave absorber according to claim 2,
In each radio wave absorption layer, when the wavelength of the incident radio wave is λ 0 , the relative permittivity of the dielectric layer of each radio wave absorption layer is ε r , and the specific impedance of the incident side and the transmission side region is Z 0 , the thickness of the body layer d, and the impedance Z s of the impedance layers,
Figure 2004214231
 A transmission type radio wave absorber that can be calculated by 請求項１〜３のいずれかに記載の透過型電波吸収装置であって、
周波数５．８ＧＨｚ程度の電波の入射角度が約４５度の時に、電波の吸収減衰量が−２０ｄＢ以上である透過型電波吸収装置。The transmission type radio wave absorber according to claim 1,
A transmission-type radio wave absorption device having a radio wave absorption attenuation of -20 dB or more when an incident angle of a radio wave having a frequency of about 5.8 GHz is about 45 degrees.
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