JP4259078B2

JP4259078B2 - Building materials

Info

Publication number: JP4259078B2
Application number: JP2002278843A
Authority: JP
Inventors: 晶彦伊藤; 英実中島
Original assignee: Toppan Inc
Current assignee: Toppan Inc
Priority date: 2002-09-25
Filing date: 2002-09-25
Publication date: 2009-04-30
Anticipated expiration: 2022-09-25
Also published as: JP2004119565A

Description

【０００１】
【発明の属する技術分野】
本発明は、電波吸収体及び電波吸収能を有する建材に関し、特に無線機器を使用しているオフィス等の部屋に好適に利用できるものである。
【０００２】
【従来の技術】
【特許文献１】
特公平６−９９９７２号公報
【特許文献２】
特開平１０−１６９０３９号公報
【特許文献３】
特開平９−１６２５８９号公報
【特許文献４】
特開平５−３３５８３２号公報
【０００３】
近年、事業所内ＰＨＳや無線ＬＡＮの利用が広がりを見せるなか、情報の漏洩防止や外部からの侵入電波による誤動作やノイズ防止といった点から、オフィス内での電波環境を整えることが不可欠になっており、そのような電波環境の整備用建材として、既に種々のタイプのものが提案されている。
【０００４】
例えば、特公平６−９９９７２号公報には、金属やフェライトなどの電磁シ−ルド建材をビルの躯体に付加することで、広い周波数帯域で任意の周波数の電波を使って情報通信が出来る電磁シ−ルド・インテルジェントビルを提供することが述べられている。しかし、このような鉄板、金属網、金属メッシュ、金属箔などの電波反射体やフェライトなどの電波吸収体を電磁シ−ルド建材として用いたものでは、それらの電磁シ−ルド性に周波数選択性が無いため、遮蔽しようとする周波数以外の電波まで遮蔽してしまう。また前記電波反射体はテレビ電波を反射し、受信障害(ゴ−ストの発生)の原因となるため用いることが出来る箇所が制限される。さらに、電磁シ−ルド建材間の隙間によってシ−ルド性能が大きく低下するため、個々の建材が持つシ−ルド性能を十分発揮させるには、建材間の接続や接地など施工面での厳密性が要求される。
【０００５】
特開平１０−１６９０３９号公報は、このような問題点を解消するもので、線状のアンテナ素子を定期的に配列させることで遮蔽しようとする特定周波数の電波のみを遮蔽し、建材間の接続や接地も必要ないという優れたものである。しかし、その遮蔽は反射損失によるものが大部分であるため、オフィス内部において反射電波による画面の揺らぎや誤動作などが起こる場合があるのが問題である。
【０００６】
特開平９−１６２５８９号公報や特開平５−３３５８３２号公報の発明は、共にこのようなオフィス内部における電波反射に起因する問題を解消するもの、即ち特定周波数の電波を選択的に吸収するものであり、特開平９−１６２５８９号公報の発明は、導電体より大きく絶縁体より小さい電気抵抗値を持つエレメントを配列させて特定周波数（以上）の電波を吸収するもの、特開平５−３３５８３２号公報の発明は、抵抗皮膜と電波反射体とを誘電体厚さがこの誘電体内における電波波長の４分の１）を挟んで配置し特定周波数の電波のみを選択的に吸収する、いわゆるλ／４型電波吸収体に関するものである。
【０００７】
しかし、これらの電波吸収体にもそれぞれ以下に述べるような欠点がある。即ち前者は電波の照射によってエレメント内を流れる交流電流の抵抗損失によるものであるため、微小な体積のエレメントでは、遮蔽しようとする周波数の電波においても実際的には透過が多くなり吸収可能な電波量は僅少になる。また後者は吸収量が前者に比して大きく、周波数選択性にも優れるが、この場合には吸収する周波数が低くなるにつれて誘電体の厚みが厚くなり、吸収体全体の厚みが厚くなるという問題がある。
【０００８】
【発明が解決しようとする課題】
本願出願人は、λ／４型電波吸収体の反射板と吸収膜の間に位相調整層をもうけ吸収体を薄型化する事を出願（特願２００１−２６２０７７）しているが、この吸収体においても誘電体の厚みが必要なためフィルム状に形成することは難しい。
【０００９】
また電波吸収体をフィルム状に形成できたとしても、実際の施工等を考えた場合には壁の表面には壁紙等が貼られることが多く、その下にフィルム等を貼るのが困難な場合も多い。
【００１０】
本発明は、電波吸収体の上記のような問題を解決することを目的としてなされたもので、特定周波数の電波のみを吸収、遮断し、他の周波数の電波は遮断するため、その特定の周波数を用いた通信に適した環境をもたらす薄型の電波吸収体又は電磁波吸収能を有する建材を提供することを課題とする。
【００１１】
本発明において上記の課題を達成するために、まず請求項１の発明では、導電体層と、前記導電体層に形成された特定パターンからなる電磁波透過開口部と、前記電磁波透過開口部の端部と電気的に結合する抵抗体と、を備えることを特徴とする建材としたものである。
【００１２】
また請求項２の発明では、請求項１に記載の建材であって、導電体層は、金属板であることを特徴とする建材としたものである。
【００１３】
また請求項３の発明では、請求項１に記載の建材であって、更に、導電体層を支持する基材と、備え、導電体層は、前記基材上に積層されていることを特徴とする建材としたものである。
【００３０】
【発明の実施の形態】
以下、本発明の実施形態を詳細に説明する。
【００３１】
図１に、導電体層２上に特定パターンからなる電磁波透過開口部４を設け、電磁波透過開口部４の端部と接触して電気的に結合するように抵抗体３を設けた電波吸収体１を示す。
【００３２】
図２に、プラスチックフィルム（誘電体基材５）上に導電体層２を設け、導電体層２上に特定パターンからなる電磁波透過開口部４を設け、電磁波透過開口部４の端部と接触して電気的に結合するように抵抗体３を設けた電波吸収体１を示す。
【００３３】
図３に、プラスチックフィルム（誘電体基材５）上に導電体層２を設け、導電体層２上に特定パターンからなる電磁波透過開口部４を設け、誘電体基材５を介し電磁波透過開口部４の端部とコンデンサを形成して電気的に結合するように抵抗体３を設けた電波吸収体１を示す。
【００３４】
図４に、導電体層２上に特定パターンからなる電磁波透過開口部４を設け、電磁波透過開口部４の端部と接触して電気的に結合するように抵抗体３を設けた電波吸収体１を、壁構成材７の室内側の面に設けた電波吸収能を有する壁を示す。
【００３５】
図５に、基材８上に導電体層２を設け、導電体層２上に特定パターンからなる電磁波透過開口部４を設け、電磁波透過開口部４の端部と接触して電気的に結合するように抵抗体３を設けた電波吸収体１を、壁構成材７の室内側の面に設けた電波吸収能を有する壁を示す。
【００３６】
図６に、基材８上に抵抗体３を設け、抵抗体３上に導電体層２を設け、特定パターンからなる電磁波透過開口部４を、その端部が抵抗体３に接触して電気的に結合するように導電体層２に設けられた電波吸収体１を、壁構成材７の室内側の面に設けた電波吸収能を有する壁を示す。
【００３７】
図７に、導電体層２上に特定パターンからなる電磁波透過開口部４を設けた特定電波透過体６を、電磁波損失材を混入させた壁構成材９の室内側の面に設けた電波吸収能を有する壁を示す。
【００３８】
電波が到来している場所に、接地されていない金属棒や金属ワイヤ−などの導体を置いた場合、一部の電波は吸収され、他は導体中を流れる交番電流が作る電磁界との相互作用によって反射される。この時電波の吸収量と反射量との比（吸収量／反射量）は導体のインピ−ダンスによって変わり、インピ−ダンスがほぼ０であればその比もほぼ０となる。またこの吸収や反射は直接導体の表面に入射する電波に対してだけでなく、その導体周囲の電波に対しても起こる（但し、導体から離れれば離れる程、吸収や反射量は少なくなる）。導体と電波の相互作用（吸収、反射）は導体と電波が共鳴する場合に大きくなる。
【００３９】
金属板上に開口部を設けた場合には同じ大きさの金属棒と双対関係にあることが知られている。ただし、２分の１波長の長さを持つ直線型金属棒の場合には電界と平行においた場合に最も共鳴が大きくなるが、同じ大きさの開口部では、磁界に平行においた場合に最も共鳴が大きくなる。このように開口部を設けた金属板を電波が到来している場所においた場合、大部分の電波は金属板により反射され、一部の電波は開口部において共鳴、再放射されることにより透過することとなる。
【００４０】
即ち図８〜１０のように開放端を持つ線状形状の電磁波透過開口部４を配列した面では、双対関係にある導体の開放端間の距離が電波波長の２分の１の場合に最も共鳴し、再放射により透過する。言い換えると、この長さの電磁波透過開口部４と共鳴しない波長（周波数）の電波にとってはこの面は一様な導電体面と同等となりその大部分が反射する。共鳴する電波の波長は、図８のような直線形状の場合にはその長さが電波波長の２分の１になり、図４や図５のように枝分かれを持つ形状では中心点から開放端までの距離が電波波長の４分の１となる。
【００４１】
また図１１〜１３のような環状の電磁波透過開口部４を配した場合には、双対関係にある環状導体の周囲長が電波波長とほぼ等しい場合に共鳴し、この配列面が特定周波数の電波に対する電磁波透過開口部となる。
【００４２】
さらに、二種以上の電磁波透過開口部を組み合わせることにより複数の周波数について電波を透過することが可能となる。
【００４３】
このような電磁波透過開口部に抵抗体を設置させた場合、共振条件における開口部周囲に発生する電流をこの抵抗体が熱に変換することにより外部に放出するため電磁波の反射を押さえることが可能となる。抵抗体については開放末端を持つ形状の場合には電界密度が最も高くなる中央部に設置することが好ましいが、吸収性能が確保されるのであれば大きさ、位置については特に問題がない。
【００４４】
本発明の電波吸収体は、以上に述べたような導電体上に設けた電磁波透過開口部の持つ性質および抵抗体の性質を利用したもので、透過しようとする周波数の電波（但し、その波長はアンテナパターンを形成した基材の誘電率、厚み、さらには吸収体を設置する壁等の建材の構成材の誘電率、厚み等を考慮し算出した波長）と共鳴するような長さの電磁波透過開口部を配列し、そこに抵抗体を設置することにより電波吸収体を構成するものである。
【００４５】
また本発明の電波吸収能を有する建材は、以上に述べたような導電体上に設けた電磁波透過開口部の持つ性質および抵抗体の性質を利用したもので、透過しようとする周波数の電波（但し、その波長はアンテナパターンを形成した基材の誘電率、厚み、さらには吸収体を設置する壁等の建材の構成材の誘電率、厚み等を考慮し算出した波長）と共鳴するような長さの電磁波透過開口部を配列し、そこに抵抗体を設置するまたは壁等の建材の構成材に電磁波損失材を混入することにより電波吸収能を有する建材を構成するものである。
【００４６】
このような電波吸収体又は電波吸収能を有する建材の吸収性能は、実際にはあるインピ−ダンスを持つ導電体中を流れる交番電流の大きさと、抵抗体の抵抗値および開口部の端部と抵抗体の接触面積（誘電体基板を介してコンデンサを形成する場合はコンデンサの電極面積）によって決まるため、電磁波透過開口部の線幅は大きい程、個々の電磁波透過開口部間の間隔は小さい程、開口部の端部と抵抗体の接触面積（或いは電極面積）は大きいほど良くなる。しかし同時に、透過しようとする周波数の電波以外の（周波数が赤外光以上のものを含む）電磁波の導電体表面における反射も小さくなるため周波数選択性が悪くなる。そこで実用上は、吸収しようとする周波数の電波に対する透過性能と周波数選択性を考慮して、電磁波透過開口部の線幅、個々の電磁波透過開口部の間隔、抵抗体の抵抗値及び接触面積（或いは電極面積）が決定される。
【００４７】
また、電波吸収能を有する建材で、抵抗体を用いない場合においても、電波が透過する壁等の建材の構成材本体に電磁波損失材を混入させることにより透過してきた特定周波数の電磁波を吸収させることも可能である。
【００４８】
上記の説明から、わかるように、壁等の建材の構成材に、電波吸収体や特定電波透過体を直接設けても良いし、それらを基材上に構成した後に、壁等の建材の構成材に設けても良い。
【００４９】
さらに、壁等の建材の構成材に混入する電磁波損失材についても電波進行方向に対しては均一でも濃度変化があっても良い。
【００５０】
ここでは図８〜１３まで、６種類の電磁波透過開口部４を図示したが、電磁波透過開口部の形状がこれらに限定されるものでないことは、前記の説明で明らかである。
【００５１】
導電体としては金属、導電性酸化物、導電性窒化物、導電性炭化物等があげられるがこれに限定するものではない。
【００５２】
抵抗体としては金属、導電性酸化物、導電性窒化物、導電性炭化物、カーボン等があげられるがこれに限定するものではない。
【００５３】
導電体層の厚みとしては１０Åから１０ｍｍであり、フィルム形状とする場合には好ましくは５０Åから５０μｍ、さらに好ましくは１μｍから１５μｍである。
【００５４】
基材上に導電体層を設ける場合の基材としては樹脂フィルム、樹脂板、木板、セラミック板、ガラス板等が上げられるが、その材質はこれらに限定するものではなく、気孔率も制限されない。
【００５５】
壁等の建材の構成材としては石膏、セメント、木、樹脂、セラミック、ガラス等があげられるがこれに限定するものではない。
【００５６】
上記の条件より、透明な導電体（ＩＴＯ等）に電磁波透過開口部を形成し、壁等の建材の構成材も透明な部材（ガラス等）により構成した透明な電波吸収能を有する壁等の建材も本発明に含まれるものとする。
【００５７】
【実施例】
以下、本発明の実施例を具体的に説明する。
【００５８】
以下の実施例１〜４及び比較例１と２について、１０ＧＨｚにおいて電波を吸収、シールドする性能を表１に示す。測定は自由空間において行い、透過減衰量測定は透過損失法、反射減衰量測定は反射電力法を用いて行った。測定範囲は２ＧＨｚから１８ＧＨｚの範囲で行いネットワークアナライザー（ヒューレッドパッカード社製ＨＰ８７２２Ｃ）のＳ２１モードにおいて測定した。
【００５９】
（実施例１）
厚さ１００μｍのＰＥＴフィルム上に１５μｍのアルミ箔を貼り合わせたフィルムに７．５ｍｍ×０．６ｍｍの電磁波透過開口部を設け、電波開口部の端部にＩＴＯからなる抵抗体を張り合わせることにより電波吸収体を作製した。
【００６０】
（実施例２）
厚さ２ｍｍのアルミ板に４．８ｍｍ×０．６ｍｍの電磁波透過開口部を設け、電波開口部の端部にＩＴＯからなる抵抗体を張り合わせた電波吸収体を、厚さ２０ｍｍの石膏板上に設けた電波吸収能を有する壁を作製した。
【００６１】
（実施例３）
厚さ２ｍｍのアルミ板に３．０ｍｍ×０．６ｍｍの電磁波透過開口部を設け、電波開口部の端部にＩＴＯからなる抵抗体を張り合わせた電波吸収体を、厚さ２０ｍｍの石膏とカーボンを混合して作成した板上に設けた電波吸収能を有する壁を作製した。
【００６２】
（実施例４）
厚さ２ｍｍのアルミ板に３．０ｍｍ×０．６ｍｍの電磁波透過開口部を設けた特定電波透過体を、厚さ２０ｍｍの石膏とカーボンを混合して作成した板上に設けた電波吸収能を有する壁を作製した。
【００６３】
（比較例１）
厚さ１００μｍのＰＥＴフィルム上に１５μｍのアルミ箔を貼り合わせたフィルムにより電磁波シールド性を有するフィルムを作製した。
【００６４】
（比較例２）
厚さ１００μｍのＰＥＴフィルム上に１５μｍのアルミ箔を貼り合わせたフィルムに７．５ｍｍ×０．６ｍｍの電磁波透過開口部を設け、電磁波シールド性を有するフィルムを作製した。
【００６５】
【表１】

【００６６】
比較例１では測定範囲全体において高いシールド性能を示し、すべての周波数を反射してしまい、比較例２においては１８ＧＨｚ付近においては高いシールド性能を示したが反射量の低下は確認されず、１０ＧＨｚにおいては反射量の低下が確認されたが、シールド性能が大幅に低下してしまっていた。この結果から、比較例２では１０ＧＨｚにおいて透過する電磁波が増加したために反射量が減少したと考えられる。これに対して、実施例１〜４では、測定範囲全体において高いシールド性能を示し、かつ目的周波数である１０ＧＨｚ付近においては、反射料の低下が確認されたにもかかわらずシールド性能の低下はほとんど確認されず、高い電波吸収能が確認された。
【００６７】
【発明の効果】
以上の詳述したように、本発明によれば導電体面上に電磁波透過開口部を周期的に配列させ、そこに抵抗体を設けていることから、特定周波数の電磁波のみを吸収、遮蔽し、他の周波数の電波は遮蔽する電波吸収体及び電波吸収能を有する建材を得ることが出来る。
【００６８】
さらに導電体、抵抗体ともにひるむ形状とすればフレキシビリティーに富み、薄型の電波吸収体を得ることが出来る。
【図面の簡単な説明】
【図１】本発明に係わる周波数選択性を持つ電波吸収体の実施の１形態を示す図である。
【図２】本発明に係わる周波数選択性を持つ電波吸収体の実施の１形態を示す図である。
【図３】本発明に係わる周波数選択性を持つ電波吸収体の実施の１形態を示す図である。
【図４】本発明に係わる周波数選択性を持つ電波吸収能を有する壁の実施の１形態を示す図である。
【図５】本発明に係わる周波数選択性を持つ電波吸収体能を有する壁の実施の１形態を示す図である。
【図６】本発明に係わる周波数選択性を持つ電波吸収体能を有する壁の実施の１形態を示す図である。
【図７】本発明に係わる周波数選択性を持つ電波吸収体能を有する壁の実施の１形態を示す図である。
【図８】本発明に係わる周波数選択性を持つ電波吸収体又は電波吸収体能を有する建材の電波反射面(開口素子配列面)を示す図である。
【図９】本発明に係わる周波数選択性を持つ電波吸収体又は電波吸収体能を有する建材の電波反射面(開口素子配列面)を示す図である。
【図１０】本発明に係わる周波数選択性を持つ電波吸収体又は電波吸収体能を有する建材の電波反射面(開口素子配列面)を示す図である。
【図１１】本発明に係わる周波数選択性を持つ電波吸収体又は電波吸収体能を有する建材の電波反射面(開口素子配列面)を示す図である。
【図１２】本発明に係わる周波数選択性を持つ電波吸収体又は電波吸収体能を有する建材の電波反射面(開口素子配列面)を示す図である。
【図１３】本発明に係わる周波数選択性を持つ電波吸収体又は電波吸収体能を有する建材の電波反射面(開口素子配列面)を示す図である。
【符号の説明】
１…電波吸収体
２…導電体層
３…抵抗体
４…開口部
５…誘電体基材
６…特定電波透過体
７…壁構成材
８…基材
９…壁構成材（電磁波損失材を混入させたもの）[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a radio wave absorber and a building material having radio wave absorptivity, and can be suitably used particularly in a room such as an office using a radio device.
[0002]
[Prior art]
[Patent Document 1]
Japanese Patent Publication No. 6-99972 [Patent Document 2]
JP-A-10-169039 [Patent Document 3]
JP-A-9-162589 [Patent Document 4]
JP-A-5-335832 Publication
In recent years, it has become indispensable to prepare the radio environment in the office from the viewpoints of preventing information leakage and malfunction and noise due to invading radio waves from the outside as the use of PHS and wireless LAN in offices is spreading. Various types of building materials have already been proposed as maintenance materials for such radio wave environments.
[0004]
For example, Japanese Patent Publication No. 6-99972 discloses an electromagnetic system that can communicate information using radio waves of an arbitrary frequency in a wide frequency band by adding an electromagnetic shielding building material such as metal or ferrite to a building frame. -It is stated that Ludo Intelgent Building will be provided. However, when using electromagnetic wave reflectors such as iron plates, metal nets, metal meshes and metal foils and electromagnetic wave absorbers such as ferrite as electromagnetic shield building materials, their frequency characteristics are reduced. Therefore, even radio waves other than the frequency to be shielded are shielded. Further, the radio wave reflector reflects television radio waves and causes reception disturbance (ghosting), so that the locations where it can be used are limited. Furthermore, since the shield performance is greatly reduced by the gaps between the electromagnetic shield building materials, the strictness in terms of construction such as connection between the building materials and grounding is necessary in order to fully demonstrate the shield performance of each building material. Is required.
[0005]
Japanese Patent Laid-Open No. 10-169039 solves such problems, and by periodically arranging linear antenna elements, only radio waves of a specific frequency to be shielded are shielded, and connection between building materials It is an excellent one that does not require grounding. However, since the shielding is mostly due to reflection loss, there is a problem that screen fluctuations or malfunctions may occur due to reflected radio waves inside the office.
[0006]
The inventions of JP-A-9-162589 and JP-A-5-335832 both solve such problems caused by reflection of radio waves inside the office, that is, selectively absorb radio waves of a specific frequency. In the invention of Japanese Patent Laid-Open No. 9-162589, an element having an electric resistance value larger than a conductor and smaller than that of an insulator is arranged to absorb a radio wave of a specific frequency (or higher), Japanese Patent Laid-Open No. 5-335832 In the present invention, a resistive film and a radio wave reflector are arranged with a dielectric thickness sandwiching a quarter of the radio wave wavelength in the dielectric so as to selectively absorb only radio waves of a specific frequency, so-called λ / 4. Type electromagnetic wave absorber.
[0007]
However, these wave absorbers also have the following drawbacks. In other words, the former is due to resistance loss of alternating current that flows in the element due to the irradiation of radio waves. Therefore, in a minute volume element, radio waves of frequencies that are to be shielded are actually transmitted and can be absorbed. The amount will be small. In the latter case, the amount of absorption is larger than that of the former, and the frequency selectivity is excellent, but in this case, the thickness of the dielectric increases as the frequency of absorption decreases, and the thickness of the entire absorber increases. There is.
[0008]
[Problems to be solved by the invention]
The applicant of the present application has filed an application (Japanese Patent Application No. 2001-262077) to reduce the thickness of the absorber by providing a phase adjusting layer between the reflector of the λ / 4 type wave absorber and the absorbing film. In this case, it is difficult to form a film because the thickness of the dielectric is required.
[0009]
Even if the electromagnetic wave absorber can be formed into a film, when considering the actual construction, etc., it is often difficult to apply a film or the like underneath the wall surface. There are also many.
[0010]
The present invention was made for the purpose of solving the above-mentioned problems of the radio wave absorber, and absorbs and blocks only radio waves of a specific frequency and blocks radio waves of other frequencies. It is an object of the present invention to provide a thin radio wave absorber or a building material having an electromagnetic wave absorbing ability that brings about an environment suitable for communication using the antenna.
[0011]
In order to achieve the above object in the present invention, first, in the invention of claim 1, a conductor layer, an electromagnetic wave transmission opening formed of a specific pattern formed in the conductor layer, and an end of the electromagnetic wave transmission opening The building material is characterized by comprising a resistor that is electrically coupled to the portion .
[0012]
The invention of claim 2 is the building material according to claim 1, wherein the conductor layer is a metal plate .
[0013]
Moreover, in invention of Claim 3, it is the building material of Claim 1, Comprising: The base material which supports a conductor layer is provided further, A conductor layer is laminated | stacked on the said base material, It is characterized by the above-mentioned. It is a building material .
[0030]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail.
[0031]
In FIG. 1, a radio wave absorber in which an electromagnetic wave transmission opening 4 having a specific pattern is provided on a conductor layer 2 and a resistor 3 is provided so as to be in contact with and electrically coupled to an end of the electromagnetic wave transmission opening 4. 1 is shown.
[0032]
In FIG. 2, the conductor layer 2 is provided on the plastic film (dielectric substrate 5), the electromagnetic wave transmission opening 4 having a specific pattern is provided on the conductor layer 2, and is in contact with the end of the electromagnetic wave transmission opening 4. Then, the radio wave absorber 1 provided with the resistor 3 so as to be electrically coupled is shown.
[0033]
In FIG. 3, the conductor layer 2 is provided on the plastic film (dielectric substrate 5), the electromagnetic wave transmission opening 4 having a specific pattern is provided on the conductor layer 2, and the electromagnetic wave transmission opening is provided through the dielectric substrate 5. 1 shows a radio wave absorber 1 in which a resistor 3 is provided so as to be electrically coupled with an end portion of a portion 4.
[0034]
In FIG. 4, a radio wave absorber in which an electromagnetic wave transmission opening 4 having a specific pattern is provided on the conductor layer 2 and a resistor 3 is provided so as to be in contact with and electrically coupled to the end of the electromagnetic wave transmission opening 4. Reference numeral 1 denotes a wall having radio wave absorption ability provided on the surface of the wall constituting member 7 on the indoor side.
[0035]
In FIG. 5, the conductor layer 2 is provided on the base material 8, the electromagnetic wave transmission opening 4 having a specific pattern is provided on the conductor layer 2, and is electrically coupled in contact with the end of the electromagnetic wave transmission opening 4. A wall having a radio wave absorbing ability is shown in which the radio wave absorber 1 provided with the resistor 3 is provided on the indoor side surface of the wall constituting material 7.
[0036]
In FIG. 6, the resistor 3 is provided on the substrate 8, the conductor layer 2 is provided on the resistor 3, and the electromagnetic wave transmitting opening 4 having a specific pattern is electrically connected to the resistor 3 at the end thereof. The wall which has the radio wave absorptivity which provided the electromagnetic wave absorber 1 provided in the conductor layer 2 so that it might couple | bond together in the indoor side surface of the wall constituent material 7 is shown.
[0037]
FIG. 7 shows a radio wave absorption in which a specific radio wave transmission body 6 provided with an electromagnetic wave transmission opening 4 having a specific pattern on the conductor layer 2 is provided on the indoor side surface of a wall component 9 mixed with an electromagnetic wave loss material. The wall which has a function is shown.
[0038]
When a conductor such as a metal rod or metal wire that is not grounded is placed where radio waves arrive, some radio waves are absorbed and others interact with the electromagnetic field created by the alternating current flowing in the conductor. Reflected by action. At this time, the ratio (absorption amount / reflection amount) between the absorption amount and the reflection amount of the radio wave varies depending on the impedance of the conductor, and if the impedance is almost zero, the ratio becomes almost zero. Further, this absorption and reflection occurs not only with respect to the radio wave directly incident on the surface of the conductor, but also with respect to the radio wave around the conductor (however, the further away from the conductor, the smaller the absorption and reflection amount). The interaction (absorption, reflection) between the conductor and the radio wave is increased when the conductor and the radio wave resonate.
[0039]
It is known that when an opening is provided on a metal plate, it has a dual relationship with a metal bar of the same size. However, in the case of a linear metal rod having a length of one-half wavelength, the resonance is the largest when placed parallel to the electric field, but at the opening of the same size, the resonance is greatest when placed parallel to the magnetic field. Resonance increases. When a metal plate with an opening is placed in a place where radio waves arrive, most of the radio waves are reflected by the metal plate, and some of the radio waves are transmitted through resonance and re-radiation at the openings. Will be.
[0040]
That is, in the plane in which the linear electromagnetic wave transmission openings 4 having open ends as shown in FIGS. 8 to 10 are arranged, the distance between the open ends of the conductors in the dual relationship is most half of the radio wave wavelength. Resonates and is transmitted by re-radiation. In other words, for a radio wave having a wavelength (frequency) that does not resonate with the electromagnetic wave transmission opening 4 having this length, this surface is equivalent to a uniform conductor surface and most of the surface is reflected. The wavelength of the resonating radio wave is half the length of the radio wave wavelength in the case of a straight line shape as shown in FIG. 8, and in the shape having a branch as shown in FIGS. Is a quarter of the radio wave wavelength.
[0041]
When the annular electromagnetic wave transmission opening 4 as shown in FIGS. 11 to 13 is arranged, resonance occurs when the circumference of the annular conductor having a dual relationship is substantially equal to the radio wave wavelength, and this arrangement surface is a radio wave having a specific frequency. It becomes an electromagnetic wave transmission opening with respect to.
[0042]
Furthermore, by combining two or more types of electromagnetic wave transmission openings, it is possible to transmit radio waves for a plurality of frequencies.
[0043]
When a resistor is installed in such an electromagnetic wave transmission opening, the current generated around the opening under resonance conditions is released to the outside by converting the current into heat, so that reflection of the electromagnetic wave can be suppressed. It becomes. In the case of a resistor having a shape having an open end, the resistor is preferably installed at the center where the electric field density is highest, but there is no particular problem with respect to the size and position as long as the absorption performance is ensured.
[0044]
The radio wave absorber of the present invention utilizes the property of the electromagnetic wave transmitting opening provided on the conductor as described above and the property of the resistor, and the radio wave of the frequency to be transmitted (however, its wavelength Is a length of electromagnetic wave that resonates with the dielectric constant and thickness of the substrate on which the antenna pattern is formed, and the wavelength calculated taking into account the dielectric constant and thickness of the building material such as the wall where the absorber is installed. A radio wave absorber is configured by arranging transmission apertures and installing resistors therein.
[0045]
Further, the building material having the radio wave absorption capability of the present invention utilizes the property of the electromagnetic wave transmission opening provided on the conductor and the property of the resistor as described above, and the radio wave having the frequency to be transmitted ( However, the wavelength resonates with the dielectric constant and thickness of the base material on which the antenna pattern is formed, and the wavelength calculated in consideration of the dielectric constant and thickness of the building material such as the wall where the absorber is installed. An electromagnetic wave transmitting opening having a length is arranged and a resistor is installed therein, or an electromagnetic wave loss material is mixed into a building material such as a wall to constitute a building material having radio wave absorption ability.
[0046]
The absorption performance of such a radio wave absorber or a building material having radio wave absorption capability is actually the magnitude of the alternating current flowing through a conductor having a certain impedance, the resistance value of the resistor, and the end of the opening. Since the contact area of the resistor is determined by the contact area of the resistor (when the capacitor is formed via the dielectric substrate, the electrode area of the capacitor), the larger the line width of the electromagnetic wave transmission openings, the smaller the interval between the individual electromagnetic wave transmission openings. The larger the contact area (or electrode area) between the end of the opening and the resistor, the better. However, at the same time, reflection of electromagnetic waves other than radio waves having a frequency to be transmitted (including those having a frequency equal to or higher than that of infrared light) on the surface of the conductor is reduced, resulting in poor frequency selectivity. Therefore, in practice, considering the transmission performance and frequency selectivity for radio waves of the frequency to be absorbed, the line width of the electromagnetic wave transmission openings, the interval between the individual electromagnetic wave transmission openings, the resistance value of the resistor and the contact area ( Alternatively, the electrode area) is determined.
[0047]
In addition, even in the case where a resistor is not used in a building material having radio wave absorption ability, it absorbs electromagnetic waves of a specific frequency that has been transmitted by mixing an electromagnetic wave loss material into the building material main body of the building material such as a wall through which radio waves are transmitted. It is also possible.
[0048]
As can be seen from the above description, the component of the building material such as a wall may be directly provided with a radio wave absorber or a specific radio wave transmitting material, or after they are configured on the base material, the configuration of the building material such as the wall It may be provided on the material.
[0049]
Further, the electromagnetic wave loss material mixed in the building material such as a wall may be uniform or change in concentration in the radio wave traveling direction.
[0050]
Here, six types of electromagnetic wave transmission openings 4 are illustrated in FIGS. 8 to 13, but it is apparent from the above description that the shape of the electromagnetic wave transmission openings is not limited to these.
[0051]
Examples of the conductor include metals, conductive oxides, conductive nitrides, and conductive carbides, but are not limited thereto.
[0052]
Examples of the resistor include, but are not limited to, metals, conductive oxides, conductive nitrides, conductive carbides, and carbon.
[0053]
The thickness of the conductor layer is from 10 mm to 10 mm, and in the case of a film shape, it is preferably from 50 mm to 50 μm, more preferably from 1 μm to 15 μm.
[0054]
Resin films, resin plates, wood plates, ceramic plates, glass plates, etc. are raised as the substrate when the conductor layer is provided on the substrate, but the material is not limited to these, and the porosity is not limited. .
[0055]
Building materials such as walls include, but are not limited to, gypsum, cement, wood, resin, ceramic, glass and the like.
[0056]
Based on the above conditions, an electromagnetic wave transmitting opening is formed in a transparent conductor (ITO, etc.), and a building material such as a wall is also made of a transparent member (glass, etc.) and has a transparent radio wave absorption capability. Building materials are also included in the present invention.
[0057]
【Example】
Examples of the present invention will be specifically described below.
[0058]
Table 1 shows the performance of absorbing and shielding radio waves at 10 GHz for the following Examples 1 to 4 and Comparative Examples 1 and 2. The measurement was performed in free space, the transmission attenuation was measured using the transmission loss method, and the reflection attenuation was measured using the reflected power method. The measurement range was 2 GHz to 18 GHz, and the measurement was performed in the S21 mode of a network analyzer (HP8722C manufactured by Hured Packard).
[0059]
Example 1
By providing a 7.5 mm x 0.6 mm electromagnetic wave transmission opening on a film obtained by bonding a 15 μm aluminum foil on a 100 μm thick PET film, and attaching a resistor made of ITO to the end of the radio wave opening A radio wave absorber was prepared.
[0060]
(Example 2)
An electromagnetic wave absorber in which a 4.8 mm × 0.6 mm electromagnetic wave transmission opening is provided on a 2 mm thick aluminum plate, and a resistor made of ITO is bonded to the end of the radio wave opening, is placed on a 20 mm thick gypsum plate. A provided wall having radio wave absorption ability was produced.
[0061]
(Example 3)
An electromagnetic wave absorber in which a 3.0 mm × 0.6 mm electromagnetic wave transmission opening is provided on a 2 mm thick aluminum plate, and a resistor made of ITO is bonded to the end of the radio wave opening, gypsum and carbon having a thickness of 20 mm are bonded. A wall having radio wave absorption ability provided on a plate prepared by mixing was prepared.
[0062]
(Example 4)
A radio wave absorber provided on a plate made by mixing a 20 mm thick gypsum and carbon with a specific radio wave transmitting body having a 3.0 mm × 0.6 mm electromagnetic wave transmitting opening on a 2 mm thick aluminum plate The wall which has is produced.
[0063]
(Comparative Example 1)
A film having electromagnetic wave shielding properties was produced from a film obtained by bonding a 15 μm aluminum foil on a 100 μm thick PET film.
[0064]
(Comparative Example 2)
An electromagnetic wave transmitting opening of 7.5 mm × 0.6 mm was provided on a film obtained by bonding a 15 μm aluminum foil on a 100 μm thick PET film to produce a film having electromagnetic wave shielding properties.
[0065]
[Table 1]

[0066]
Comparative Example 1 showed high shielding performance over the entire measurement range and reflected all frequencies, and Comparative Example 2 showed high shielding performance near 18 GHz, but no decrease in the amount of reflection was confirmed, and at 10 GHz. Although the fall of the amount of reflection was confirmed, the shield performance had fallen significantly. From this result, it is considered that the amount of reflection decreased in Comparative Example 2 because the electromagnetic wave transmitted at 10 GHz increased. On the other hand, in Examples 1 to 4, high shielding performance was shown in the entire measurement range, and in the vicinity of 10 GHz, which is the target frequency, the shielding performance was hardly lowered even though the decline in the reflective material was confirmed. It was not confirmed and high radio wave absorption ability was confirmed.
[0067]
【The invention's effect】
As described in detail above, according to the present invention, the electromagnetic wave transmission openings are periodically arranged on the conductor surface, and the resistors are provided there, so that only electromagnetic waves of a specific frequency are absorbed and shielded, A radio wave absorber that shields radio waves of other frequencies and a building material having radio wave absorption ability can be obtained.
[0068]
Furthermore, if both the conductor and the resistor are formed in a shape that is constrained, a highly flexible and thin wave absorber can be obtained.
[Brief description of the drawings]
FIG. 1 is a diagram showing an embodiment of a radio wave absorber having frequency selectivity according to the present invention.
FIG. 2 is a diagram showing an embodiment of a radio wave absorber having frequency selectivity according to the present invention.
FIG. 3 is a diagram showing an embodiment of a radio wave absorber having frequency selectivity according to the present invention.
FIG. 4 is a diagram showing an embodiment of a wall having radio frequency absorption capability with frequency selectivity according to the present invention.
FIG. 5 is a diagram showing an embodiment of a wall having a radio wave absorber function with frequency selectivity according to the present invention.
FIG. 6 is a diagram showing an embodiment of a wall having a radio wave absorber function with frequency selectivity according to the present invention.
FIG. 7 is a diagram showing an embodiment of a wall having a radio wave absorber function with frequency selectivity according to the present invention.
FIG. 8 is a view showing a radio wave reflecting surface (aperture element array surface) of a radio wave absorber having frequency selectivity according to the present invention or a building material having radio wave absorber capabilities.
FIG. 9 is a view showing a radio wave reflecting surface (aperture element array surface) of a radio wave absorber having frequency selectivity according to the present invention or a building material having radio wave absorber capabilities.
FIG. 10 is a view showing a radio wave reflecting surface (aperture element array surface) of a radio wave absorber having frequency selectivity according to the present invention or a building material having radio wave absorber capabilities.
FIG. 11 is a view showing a radio wave reflecting surface (aperture element array surface) of a radio wave absorber having frequency selectivity according to the present invention or a building material having radio wave absorber capabilities.
FIG. 12 is a view showing a radio wave reflecting surface (aperture element array surface) of a radio wave absorber having frequency selectivity according to the present invention or a building material having radio wave absorber capabilities.
FIG. 13 is a view showing a radio wave reflecting surface (aperture element array surface) of a radio wave absorber having frequency selectivity according to the present invention or a building material having radio wave absorber capabilities.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Radio wave absorber 2 ... Conductor layer 3 ... Resistor 4 ... Opening part 5 ... Dielectric base material 6 ... Specific radio wave transmitting body 7 ... Wall constituent material 8 ... Base material 9 ... Wall constituent material (electromagnetic wave loss material is mixed) )

Claims

A conductor layer;
An electromagnetic wave transmission opening made of a specific pattern formed in the conductor layer;
A resistor electrically coupled to an end of the electromagnetic wave transmitting opening;
A building material characterized by comprising.

The building material according to claim 1,
The conductor layer must be a metal plate
A building material characterized by

The building material according to claim 1,
And a substrate that supports the conductor layer,
The conductor layer is laminated on the base material
A building material characterized by