JP3787615B2

JP3787615B2 - Method and apparatus for nondestructive measurement of complex permittivity

Info

Publication number: JP3787615B2
Application number: JP2001009468A
Authority: JP
Inventors: 誠平野
Original assignee: 防衛庁技術研究本部長
Priority date: 2001-01-17
Filing date: 2001-01-17
Publication date: 2006-06-21
Anticipated expiration: 2021-01-17
Also published as: JP2002214161A

Description

【０００１】
【発明の属する技術分野】
本発明は、複素誘電率の非破壊測定方法及び装置に係り、特にマイクロ波帯・ミリ波帯における複素誘電率の測定方法及び装置に関する。
【０００２】
【従来の技術】
各種材料の誘電率測定方法としては、低周波領域では誘電体材料を電極間に挟み、電極間の静電容量を測定して、その測定値と材料の寸法から誘電率を算出する方法が用いられる。
【０００３】
また、高周波領域では測定周波数範囲に共振点をもつ共振器を用意し、誘電体材料をその共振器に内挿したときとしないときの共振周波数、Ｑ等を測定し、それらの測定値の変化から複素誘電率を算出する方法、あるいは測定周波数がその通過帯域内にあるような同軸伝送路または導波管伝送路を用意し、誘電体材料をその伝送路に内挿したときとしないときの伝送特性を測定して、誘電率を算出する方法が用いられる。
【０００４】
【発明が解決しようとする課題】
本発明は、マイクロ波帯・ミリ波帯における誘電体の複素誘電率測定を対象とするものである。従来のマイクロ波帯・ミリ波帯の測定法では、測定用の試料を共振器あるいは導波管の内部に挿入して測定されていた。このため、従来法は測定用試料に前記挿入する測定器具の寸法に合わせるための加工を必要とする破壊測定法であり、試料の加工には相当の手間を要した。また、作成した試料の外形寸法、特に測定器具の内壁に接触する部分の寸法精度が低いと大きい測定誤差が生じ、正確な測定は困難であった。
【０００５】
本発明の目的は、上述した従来技術の問題点を解決し、マイクロ波やミリ波領域で被測定試料の寸法精度を得るのが困難な場合であっても、簡単な構造の回路で容易かつ正確に当該試料の誘電体の複素誘電率を測定することのできる複素誘電率の非破壊測定方法及び装置を提供するにある。
【０００６】
本発明のその他の目的や新規な特徴は後述の実施の形態において明らかにする。
【０００７】
【課題を解決するための手段】
上記目的を達成するために、本願請求項１に係る複素誘電率の非破壊測定方法は、２つのフランジ付導波管の間に被測定試料である平板形状の誘電体を挿入して隙間無く密着するように押さえ、かつ各々のフランジ及び誘電体の寸法は入射される電磁波が前記誘電体の端部に至るまでに充分減衰する寸法を有するものとし、
一方の前記導波管の開口面から一定の周波数の電磁波を入射させた際の反射係数及び透過係数を計測し、
マックスウェルの方程式から導出されたヘルムホルツ方程式を、前記２つのフランジ付導波管と前記誘電体の各領域について立て、これらをそれぞれのフランジ付導波管の開口面及びフランジ面上の境界条件式に代入するという厳密解法によって得られた連立方程式を用いて、
前記計測により得られた反射係数及び透過係数の絶対値と位相角から、前記挿入した誘電体の複素誘電率を求めることを特徴としている。
【０００８】
本願請求項２に係る複素誘電率の非破壊測定方法は、２つのフランジ付導波管の間に被測定試料である平板形状の誘電体を挿入して隙間無く密着するように押さえ、かつ各々のフランジ及び誘電体の寸法は入射される電磁波が前記誘電体の端部に至るまでに充分減衰する寸法を有するものとし、
一方の前記導波管の開口面から当該導波管で伝搬可能な周波数範囲の電磁波を入射させた際の反射係数及び透過係数を計測し、
マックスウェルの方程式から導出されたヘルムホルツ方程式を、前記２つのフランジ付導波管と前記誘電体の各領域について立て、これらをそれぞれのフランジ付導波管の開口面及びフランジ面上の境界条件式に代入するという厳密解法によって得られた連立方程式を用いて、
前記計測により得られた反射係数及び透過係数の絶対値と位相角の周波数特性から、前記挿入した誘電体の複素誘電率の周波数特性を求めることを特徴としている。
【０００９】
本願請求項３に係る複素誘電率の非破壊測定方法は、請求項１又は２において、前記被測定試料から得られた反射係数及び透過係数の絶対値と位相角から、複素誘電率と誘電正接(tanδ)を求める作業をコンピュ−タによる演算処理で実行することを特徴としている。
【００１０】
本願請求項４に係る複素誘電率の非破壊測定装置は、２つのフランジ付導波管の間に被測定試料である平板形状の誘電体を挿入して隙間無く密着するように押さえ、かつ各々のフランジ及び誘電体の寸法は入射される電磁波が前記誘電体の端部に至るまでに充分減衰する寸法を有するものとし、
一方の前記導波管の開口面の反射係数及び透過係数を反射・透過係数測定手段で計測し、
マックスウェルの方程式から導出されたヘルムホルツ方程式を、前記２つのフランジ付導波管と前記誘電体の各領域について立て、これらをそれぞれのフランジ付導波管の開口面及びフランジ面上の境界条件式に代入するという厳密解法によって得られた連立方程式を用いて、
前記計測により得られた反射係数及び透過係数の絶対値と位相角から、誘電率特定手段により前記挿入した誘電体の複素誘電率を求めることを特徴としている。
【００１２】
本願請求項５に係る複素誘電率の非破壊測定装置は、２つのフランジ付導波管の間に被測定試料である平板形状の誘電体を挿入して隙間無く密着するように押さえ、一方のフランジ付導波管の開口面から電磁波を入射させ、該開口面から前記誘電体に入射した電磁波が、それぞれのフランジ付導波管の開口面以外の位置から前記誘電体の外部に漏れることがなく、よって計測系以外の外界の電磁波的な悪影響を受けることなく反射係数及び透過係数を反射・透過係数測定手段で計測し、
マックスウェルの方程式から導出されたヘルムホルツ方程式を、前記２つのフランジ付導波管と前記誘電体の各領域について立て、これらをそれぞれのフランジ付導波管の開口面及びフランジ面上の境界条件式に代入するという厳密解法によって得られた連立方程式を用いて、
前記計測により得られた反射係数及び透過係数の絶対値と位相角から、誘電率特定手段により前記挿入した誘電体の複素誘電率を求めることを特徴としている。
【００１３】
本願請求項６に係る複素誘電率の非破壊測定装置は、その開口面より被測定試料である平板形状の誘電体の表面に電磁波を入射して、当該開口面からの反射波を計測するための第１のフランジ付導波管を有し、当該第１のフランジ付導波管のフランジが前記誘電体の表面に隙間無く密着する電磁波入力手段と、
前記誘電体を透過した電磁波を計測するための第２のフランジ付導波管を有し、当該第２のフランジ付導波管のフランジが前記誘電体の反対面に隙間無く密着する電磁波出力手段と、
前記電磁波入力手段へ電磁波を供給して、その基本モードに対する挿入された前記誘電体の反射特性を測定するとともに、前記電磁波出力手段からの電磁波を受信して、基本モードに対する前記誘電体の透過特性を測定するための反射・透過係数測定手段と、
マックスウェルの方程式から導出されたヘルムホルツ方程式を、前記２つのフランジ付導波管と前記誘電体の各領域について立て、これらをそれぞれのフランジ付導波管の開口面及びフランジ面上の境界条件式に代入するという厳密解法によって得られた連立方程式を用いて、
前記反射・透過係数測定手段により測定された反射特性及び透過特性から、前記誘電体の複素誘電率を求めるために、反射係数及び透過係数と複素誘電率の関係を算出するための反射・透過係数算出手段と、
該反射・透過係数算出手段により算出された反射係数及び透過係数と複素誘電率の関係から前記誘電体の複素誘電率を特定するための誘電率特定手段とを備えたことを特徴としている。
【００１４】
本願請求項７に係る複素誘電率の非破壊測定装置は、請求項６において、前記電磁波入力手段は、高周波発生手段により発生した高周波を前記第１のフランジ付導波管の導波管部に導くためのコネクタと、該導波管部内において前記高周波を電磁波に変換するためのロッドアンテナとを有し、前記第１のフランジ付導波管の前記導波管部は前記ロッドアンテナから放射された電磁波を前記誘電体に入射させるためにその開口面まで導き、前記第１のフランジ付導波管のフランジは前記誘電体内部に入射した電磁波が、前記開口面以外の位置から前記誘電体の外部に漏れることを防ぐ構成であることを特徴としている。
【００１５】
本願請求項８に係る複素誘電率の非破壊測定装置は、請求項６又は７において、前記電磁波出力手段が、前記第２のフランジ付導波管の導波管部内に設けられて電磁波を高周波に変換するための受信用ロッドアンテナと、該受信用ロッドアンテナで受信した高周波を、高周波受信手段に導くためのコネクタとを有し、前記第２のフランジ付導波管の前記導波管部はその開口面より入射した電磁波を、前記受信用のロッドアンテナまで導き、前記第２のフランジ付導波管のフランジは前記誘電体を透過した電磁波が、前記開口面以外の位置から誘電体の外部に漏れることを防ぐ構成であることを特徴としている。
【００１６】
本願請求項９に係る複素誘電率の非破壊測定装置は、請求項６，７又は８において、前記反射・透過係数算出手段が、マックスウェルの方程式から導出されたヘルムホルツ方程式を、前記第１及び第２のフランジ付導波管と前記誘電体の各領域について立て、これらをそれぞれの前記フランジ付導波管の開口面及びフランジ面上の境界条件式に代入するという厳密解法によって得られた連立方程式を、基本モードだけでなく２つの開口面で発生する高次モードを含めた上で、基本モードの反射係数及び透過係数を算出することを特徴としている。
【００１７】
本願請求項１０に係る複素誘電率の非破壊測定装置は、請求項６，７，８又は９において、前記誘電率特定手段が、前記反射・透過係数算出手段により算出された複素誘電率と反射係数及び複素誘電率と透過係数の対応関係を用い、前記反射・透過係数測定手段により得られた反射係数及び透過係数の絶対値と位相角から、複素誘電率を直接求めることを特徴としている。
【００１８】
本願請求項１１に係る複素誘電率の非破壊測定装置は、請求項１０において、被測定試料から得られた反射係数及び透過係数の絶対値と位相角から、複素誘電率と誘電正接(tanδ)を求めるコンピュータを備えることを特徴としている。
【００１９】
【発明の実施の形態】
以下、本発明に係る複素誘電率の非破壊測定方法及び装置の実施の形態を図面に従って説明する。
【００２０】
図１は、本発明に係る複素誘電率の非破壊測定方法及び装置の実施の形態を示すブロック図で、反射・透過係数測定手段としての反射・透過特性測定装置１の信号送受端子１１と信号受信端子１２の間に誘電体内挿部２を接続する。反射・透過特性測定装置１としては、この種の測定に多く利用されているベクトルネットワークアナライザを用いる。ベクトルネットワークアナライザには、掃引周波数発振器、レベル検出器、校正回路等が含まれている。測定結果は、反射・透過特性測定装置１上の表示器に表示されると共に、データ出力端子１３を経て処理装置３に出力される。処理装置３としては、パーソナルコンピュータ等の計算機及びプリンタ等の周辺機器が必要に応じて接続できるようになっている。表示器に表示された反射係数及び透過係数の測定結果又は処理装置による処理の結果から、前記誘電体内挿部２に内挿された被測定試料である誘電体の反射・透過特性（つまり、反射係数及び透過係数の絶対値と位相角）が求められる。
【００２１】
この反射係数及び透過係数の測定にあたってはベクトルネットワークアナライザの掃引発振器の発振周波数範囲を、測定しようとする周波数を含むように設定する。複素誘電率の値は、表示器上に表示された、又はプリンタで記録された反射係数及び透過係数の絶対値（大きさ）と位相角を直接読み取り、後述の方法によって求めることができる。また、当該方法による処理を、コンピュータ化して、コンピュータによる演算処理で実行する複素誘電率特定手段を用いる構成にするとよい。
【００２２】
図２は、図１の誘電体内挿部２のうち第１のフランジ付導波管２３を含む電磁波入力手段を示すものである。このフランジ付導波管２３は導波管部２４とフランジ２５とからなり、その導波管部２４には、高周波発生手段としての機能も有する反射・透過特性測定装置１からの高周波を供給する、又は反射・透過特性測定装置１へ高周波を送出するためのケ−ブルを接続するためのコネクタ２１が設けられるとともに、このコネクタ２１より入力された高周波から電磁波を発生させ、又は受信される電磁波を高周波に変換してコネクタ２１に出力するためのロッドアンテナ２２が導波管部２４内に設けられる。前記コネクタ２１はケーブルを介し反射・透過特性測定装置１の信号送受端子１１に接続される。前記フランジ付導波管２３の導波管部２４は、ロッドアンテナ２２により発生した電磁波を被測定試料の誘電体表面まで伝搬させると共に、導波管部２４の開口面からの反射波のうち基本モ−ドだけをロッドアンテナ２２まで伝搬させ、フランジ付導波管２３のフランジ２５は誘電体内部に入射した電磁波が、前記開口面以外の位置から誘電体の外部に漏れることを防ぐためのものである。
【００２３】
図３は、誘電体内挿部２の構成例を示すものである。この誘電体内挿部２は、第１のフランジ付導波管２３を有する電磁波入力手段と、第２のフランジ付導波管３３を有する電磁波出力手段とを具備し、第１及び第２のフランジ付導波管２３，３３の中心軸を一致させて、被測定試料である平板形状の誘電体４０の表裏を挟んだ構造を持っている。
【００２４】
前記電磁波出力手段は前記誘電体４０を透過した電磁波を計測するための構成であり、導波管部３４とフランジ３５からなる第２のフランジ付導波管３３の導波管部３４内に設けられて電磁波を高周波に変換するための受信用ロッドアンテナ３２と、該受信用ロッドアンテナ３２で受信した高周波を、高周波受信手段としての前記反射・透過特性測定装置１に導くためのコネクタ３１とを有し、第２のフランジ付導波管３３の導波管部３４はその開口面より入射した電磁波を、前記受信用のロッドアンテナ３２まで導き、前記第２のフランジ付導波管３３のフランジ３５は前記誘電体４０を透過した電磁波が、前記開口面以外の位置から誘電体の外部に漏れることを防ぐものである。前記コネクタ３１はケーブルを介し信号受信端子１２に接続される。
【００２５】
なお、図示では誘電体内挿部２と反射・透過特性測定装置１との接続部がコネクタとなっているが、反射・透過特性測定装置１の信号送受端子の回路形式が導波管であればフランジで直接結合し、同軸であれば図２、図３に示したようなコネクタとする。
【００２６】
そして、誘電体内挿部２の２つのフランジ付導波管２３，３３の間に被測定試料である誘電体４０を挿入して押さえ、一方の前記導波管２３の開口面から一定の周波数又は当該導波管で伝搬可能な周波数範囲の電磁波を入射させた際の反射係数及び透過係数を前記反射・透過特性測定装置１で計測し、その計測により得られた反射係数及び透過係数の絶対値と位相角から、処理装置３にて誘電体４０の複素誘電率を求めるようにする。処理装置３は、さらに必要であれば、前記反射係数及び透過係数の絶対値と位相角から、複素誘電率と誘電正接(tanδ)を求める作業をコンピュ−タによる演算処理で実行可能な構成とする。
【００２７】
なお、ベクトルネットワークアナライザの掃引周波数発振器で、前記導波管２３で伝搬可能な周波数範囲で入射電磁波の周波数を変化させることによって、前記誘電体４０の複素誘電率の周波数特性を求めることができる。
【００２８】
前記誘電体内挿部２の構造によるフランジ付導波管の開口面における反射係数Γ及び透過係数Ｔは、マクスウェルの方程式から導出された導波管内及び誘電体内の電磁界を、入射側及び透過側の導波管開口面の境界条件式(1)
【００２９】
【数１】

に代入し、これらをまとめることにより導かれた次の連立方程式(2)を、Ｃ_１０（＝Γ）、Ｆ_１０（＝Ｔ）について解くことにより得られる。
【００３０】
【数２】

【００３１】
【数３】

【００３２】
【数４】

【００３３】
【数５】

【００３４】
【数６】

【００３５】
【数７】

【００３６】
【数８】

【００３７】
【数９】

【００３８】
【数１０】

【００３９】
【数１１】

【００４０】
【数１２】

【００４１】
【数１３】

【００４２】
【数１４】

【００４３】
【数１５】

【００４４】
【数１６】

【００４５】
【数１７】

【００４６】
【数１８】

【００４７】
【数１９】

【００４８】
【数２０】

【００４９】
【数２１】

【００５０】
【数２２】

【００５１】
図１の反射・透過特性測定装置１で、反射係数Γ及び透過係数Ｔを測定し、その値を前記連立方程式(2)に代入して解くことにより、被測定試料である誘電体４０の複素誘電率の実部ε_ｒ'及び虚部ε_ｒ"がそれぞれ求められる。なお、前記連立方程式(2)はマックスウェルの方程式から導出されたヘルムホルツ方程式を、前記第１及び第２のフランジ付導波管２３，３３と誘電体４０の各領域について立て、これらをそれぞれのフランジ付導波管の開口面及びフランジ面上の境界条件式に代入するという厳密解法によって得られた連立方程式である。
【００５２】
以上のように本発明では、開口面の反射係数Γ及び透過係数Ｔを測定して複素誘電率を求めるが、これらの測定は開口面を短絡板で短絡したときと誘電体を挿入したときとの、又は２つのフランジ付導波管の開口面同士を接合したときと誘電体を挿入したときとの比較測定によることや、反射及び透過の２種の係数をもとにして複素誘電率を求めるため精度が高く、よって正確な複素誘電率の測定が可能である。
【００５３】
以上で図１に示した本発明の実施の形態の原理的な動作を説明したが、次に、図３に示した誘電体内挿部２について詳細に説明する。まず、導波管２３，３３の長さι_１、ι_３は、長くなるほどロッドアンテナ２２、３２と開口面の間の伝送損失が大きくなるので、反射係数Γ及び透過係数Ｔが必要な精度で測定できる長さがあればよく、例えば、Ｘ帯（８.２〜１２.４ＧＨｚ）の導波管の場合には、ι_１，ι_３＝１０cm程度でよい。次に、導波管断面の寸法ａ，ｂは、一般に用いられているＸ帯方形導波管の定格寸法ａ＝２２.９mm、ｂ＝１０.２mmとしている。この寸法は、測定に不要な高次モ−ドの伝搬を抑制するように決められた定格なので、本測定法にもそのまま適用できる。
【００５４】
また、フランジ、誘電体の寸法ι_２は、式（１）を導出する際には放射条件を満足させるために無限長としているが、実際には誘電体に損失があるため無限長の必要は無く、電磁波が誘電体の端部に至るまでに充分減衰する程度の寸法があればよい。平野他「フランジ付方形導波管を用いた損失誘電体の複素誘電率の測定」、ｐｐ．６４２−６４９、Ｎｏｖ．１９９９、電子情報通信学会論文誌における検討の結果を鑑みると、ι_２＝１５〜２０cm程度あれば充分である。
【００５５】
次に本発明の実施の形態では、構造上、開口面において高次モ−ドが発生するが、これらの高次モ−ド反射波及び高次モ−ド透過波は、ロッドアンテナに到達するまでに充分減衰してしまい、反射・透過特性測定装置１では開口面における基本モ−ド反射波及び高次モ−ド透過波のみが観測される。しかし、式（１）を用いて反射係数Γ及び透過係数Ｔを算出するときには、前述の高次モ−ドを含める必要がある。平野他「フランジ付き方形導波管と導体板に挟まれた損失誘電体内の電磁界解析」、ｐｐ．５２５−５３６、Ｓｅｐ．１９９９、電子情報通信学会論文誌において検討の結果を鑑みると、ＴＥ_１０，ＴＥ_３０，ＴＥ_１２，ＴＭ_１２，ＴＥ_１４，ＴＭ_１４の６モ−ドを計算に含めれば正確な反射係数が得られることが明らかである。
【００５６】
次に、図３の誘電体内挿部２への誘電体の内挿方法について述べる。被測定試料の誘電体４０は、２つのフランジで挟むことができる平板形状の誘電体であれば何でもよい。そして、一方のフランジ付導波管２３の開口面上に誘電体４０を載せ、さらにその上から他方のフランジ付導波管３３を誘電体表面に押し当てて測定を行う。このとき、２つのフランジ付導波管２３，３３の開口面位置は一致していなければならない。また、フランジと誘電体間に空気の隙間が生じないように密着させることが好ましい。それは、空気層が生じたことによる複素誘電率の相異や誘電体の厚さｄの相異を考慮する必要がなくなるからである。従って、ある程度の力でフランジ付導波管を誘電体表面に押さえる必要があるが、あまり強く押さえても反射係数Γに変化はないので、隙間が無くなる程度でよい。
【００５７】
以上、マイクロ波帯及びミリ波帯の伝送線路として最も普及している方形導波管により誘電体内挿部２を構成した実施の形態を詳しく説明したが、円形導波管や同軸導波管でも同様に適用できることは明らかである。
【００５８】
従来の導波管による測定では、管壁に密着するような試料片の作成が必要であり、手間を要する。また、寸法精度は、本実施の形態のＸ帯ではそれほど大きな問題とはならないが、さらに周波数が高いミリ波帯では、試料片の寸法が数mm程度と小さくなるため、わずかな寸法の誤差が複素誘電率に大きく影響を与える。このため、試料片の加工や精度を必要としない本発明は、従来法に比べ有利である。
【００５９】
以上本発明の実施の形態について説明してきたが、本発明はこれに限定されることなく請求項の記載の範囲内において各種の変形、変更が可能なことは当業者には自明であろう。
【００６０】
【発明の効果】
以上説明したように、本発明によれば、測定器具の寸法に合わせた試料の精密加工を必要とせずに、試料として任意の広さの平板形状の誘電体を用いればよく、しかもその表面をフランジ付導波管で押さえるという操作のみで複素誘電率を簡単に測定できる。また、導波管の開口部またはフランジ面に、複素誘電率が既知の誘電体で蓋をすることにより、固体だけでなく液体、気体であっても、さらに高温や腐食性の媒質であっても測定が行えるという効果がある。
【図面の簡単な説明】
【図１】本発明になる複素誘電率の非破壊測定方法及び装置の実施の形態を示すブロック図である。
【図２】実施の形態における誘電体内挿部のうち電磁波入力手段を示す斜視図である。
【図３】実施の形態における誘電体内挿部の構成例を示す断面図である。
【符号の説明】
１反射・透過特性測定装置
２誘電体内挿部
２１，３１コネクタ
２２，３２ロッドアンテナ
２３，３３フランジ付導波管
２４，３４導波管部
２５，３５フランジ
４０誘電体[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a complex dielectric constant nondestructive measurement method and apparatus, and more particularly to a complex dielectric constant measurement method and apparatus in a microwave band and a millimeter wave band.
[0002]
[Prior art]
As a method for measuring the dielectric constant of various materials, a method is used in which a dielectric material is sandwiched between electrodes in the low frequency region, the capacitance between the electrodes is measured, and the dielectric constant is calculated from the measured value and the dimensions of the material. It is done.
[0003]
Also, in the high frequency region, prepare a resonator having a resonance point in the measurement frequency range, measure the resonance frequency, Q, etc. when the dielectric material is inserted into the resonator and not, and change the measured values. A method to calculate the complex dielectric constant from the above, or a coaxial transmission line or waveguide transmission line whose measurement frequency is in its passband, and when dielectric material is interpolated in the transmission line A method of calculating a dielectric constant by measuring transmission characteristics is used.
[0004]
[Problems to be solved by the invention]
The present invention is intended for the measurement of the complex permittivity of a dielectric in the microwave band and the millimeter wave band. In the conventional microwave band / millimeter wave band measurement method, measurement is performed by inserting a measurement sample into a resonator or a waveguide. For this reason, the conventional method is a destructive measurement method that requires processing for matching the dimensions of the measurement instrument to be inserted into the measurement sample, and processing the sample requires considerable effort. In addition, if the outer dimensions of the prepared sample, particularly the dimensional accuracy of the portion in contact with the inner wall of the measuring instrument, is low, a large measurement error occurs and accurate measurement is difficult.
[0005]
The object of the present invention is to solve the above-mentioned problems of the prior art, and even if it is difficult to obtain the dimensional accuracy of the sample to be measured in the microwave or millimeter wave region, It is an object of the present invention to provide a nondestructive measurement method and apparatus for a complex dielectric constant capable of accurately measuring the complex dielectric constant of a dielectric of the sample.
[0006]
Other objects and novel features of the present invention will be clarified in embodiments described later.
[0007]
[Means for Solving the Problems]
In order to achieve the above object, a non-destructive measurement method for complex permittivity according to claim 1 of the present application inserts a flat plate-like dielectric material to be measured between two flanged waveguides without gaps. The dimensions of the flanges and the dielectrics are pressed so that they are in close contact with each other, and the incident electromagnetic waves are sufficiently attenuated to reach the ends of the dielectrics.
Measure the reflection coefficient and transmission coefficient when an electromagnetic wave of a certain frequency is incident from the opening surface of one of the waveguides,
The Helmholtz equation derived from Maxwell's equation is established for each of the two flanged waveguides and the dielectric region, and these are expressed as boundary condition equations on the opening surface and flange surface of each flanged waveguide. Using simultaneous equations obtained by the exact solution of substituting
Wherein the absolute value and the phase angle of the obtained reflection and transmission coefficients by measurement, is characterized by determining the complex dielectric constant of the inserted dielectric.
[0008]
The non-destructive measurement method for complex dielectric constant according to claim 2 of the present application inserts a plate-shaped dielectric material, which is a sample to be measured, between two flanged waveguides, presses them so that they are in close contact with each other, and each The dimensions of the flange and the dielectric are such that the incident electromagnetic wave sufficiently attenuates until reaching the end of the dielectric,
Measure the reflection coefficient and transmission coefficient when an electromagnetic wave in a frequency range that can be propagated through the waveguide is incident from the opening surface of one of the waveguides,
The Helmholtz equation derived from Maxwell's equation is established for each of the two flanged waveguides and the dielectric region, and these are expressed as boundary condition equations on the opening surface and flange surface of each flanged waveguide. Using simultaneous equations obtained by the exact solution of substituting
Wherein the frequency characteristic of the absolute value and the phase angle of the obtained reflection and transmission coefficients by measurement, is characterized by obtaining the frequency characteristics of the complex dielectric constant of the inserted dielectric.
[0009]
The non-destructive measurement method for complex permittivity according to claim 3 of the present application is the method according to

claim

1 or 2, wherein the complex permittivity and the dielectric loss tangent are calculated from the absolute value and phase angle of the reflection coefficient and transmission coefficient obtained from the sample to be measured. It is characterized in that the operation for obtaining (tan δ) is executed by a calculation process by a computer.
[0010]
A complex dielectric constant nondestructive measuring apparatus according to claim 4 of the present invention inserts a flat plate-like dielectric material, which is a sample to be measured, between two flanged waveguides, presses them so as to adhere closely without gaps, and The dimensions of the flange and the dielectric are such that the incident electromagnetic wave sufficiently attenuates until reaching the end of the dielectric,
Measure the reflection coefficient and transmission coefficient of the opening surface of one of the waveguides with a reflection / transmission coefficient measuring means,
The Helmholtz equation derived from Maxwell's equation is established for each of the two flanged waveguides and the dielectric region, and these are expressed as boundary condition equations on the opening surface and flange surface of each flanged waveguide. Using simultaneous equations obtained by the exact solution of substituting
Wherein the absolute value and the phase angle of the obtained reflection and transmission coefficients by measurement, is characterized by determining the complex dielectric constant of the inserted dielectric a dielectric constant specifying means.
[0012]
A non-destructive measuring apparatus for complex permittivity according to claim 5 of the present application inserts a flat plate-like dielectric material, which is a sample to be measured, between two flanged waveguides and presses them so that they are in close contact with each other without gaps. An electromagnetic wave is incident from the opening surface of the flanged waveguide, and the electromagnetic wave incident on the dielectric from the opening surface may leak outside the dielectric from a position other than the opening surface of each flanged waveguide. Therefore, the reflection coefficient and the transmission coefficient are measured by the reflection / transmission coefficient measuring means without being adversely affected by electromagnetic waves from outside the measurement system.
The Helmholtz equation derived from Maxwell's equation is established for each of the two flanged waveguides and the dielectric region, and these are expressed as boundary condition equations on the opening surface and flange surface of each flanged waveguide. Using simultaneous equations obtained by the exact solution of substituting
Wherein the absolute value and the phase angle of the obtained reflection and transmission coefficients by measurement, is characterized by determining the complex dielectric constant of the inserted dielectric a dielectric constant specifying means.
[0013]
The non-destructive measuring apparatus for complex permittivity according to claim 6 of the present application is for making an electromagnetic wave incident on the surface of a plate-shaped dielectric material, which is a sample to be measured, from the opening surface and measuring a reflected wave from the opening surface. Electromagnetic wave input means having the first flanged waveguide, and the flange of the first flanged waveguide is in close contact with the surface of the dielectric without gaps;
An electromagnetic wave output means having a second flanged waveguide for measuring the electromagnetic wave transmitted through the dielectric, and the flange of the second flanged waveguide is in close contact with the opposite surface of the dielectric without any gap When,
Supplying electromagnetic waves to the electromagnetic wave input means, measuring the reflection characteristics of the inserted dielectric with respect to the fundamental mode, receiving electromagnetic waves from the electromagnetic wave output means, and transmitting the dielectric with respect to the fundamental mode Reflection / transmission coefficient measurement means for measuring
The Helmholtz equation derived from Maxwell's equation is established for each of the two flanged waveguides and the dielectric region, and these are expressed as boundary condition equations on the opening surface and flange surface of each flanged waveguide. Using simultaneous equations obtained by the exact solution of substituting
In order to obtain the complex dielectric constant of the dielectric from the reflection characteristic and transmission characteristic measured by the reflection / transmission coefficient measuring means, the reflection coefficient and the reflection / transmission coefficient for calculating the relationship between the transmission coefficient and the complex dielectric constant. A calculation means;
And a dielectric constant specifying means for specifying the complex dielectric constant of the dielectric from the relationship between the reflection coefficient and transmission coefficient calculated by the reflection / transmission coefficient calculating means and the complex dielectric constant.
[0014]
The complex dielectric constant nondestructive measuring apparatus according to claim 7 of the present invention is the complex dielectric constant nondestructive measuring apparatus according to claim 6 , wherein the electromagnetic wave input means applies the high frequency generated by the high frequency generating means to the waveguide section of the first flanged waveguide. A connector for guiding, and a rod antenna for converting the high frequency into electromagnetic waves in the waveguide portion, and the waveguide portion of the first flanged waveguide is radiated from the rod antenna. In order to make the electromagnetic wave incident on the dielectric, it is guided to the opening surface, and the flange of the first flanged waveguide is configured so that the electromagnetic wave incident on the inside of the dielectric has It is characterized by being configured to prevent leakage to the outside.
[0015]
The complex dielectric constant nondestructive measuring apparatus according to claim 8 of the present invention is the complex dielectric constant nondestructive measuring apparatus according to claim 6 or 7 , wherein the electromagnetic wave output means is provided in the waveguide portion of the second flanged waveguide to transmit the electromagnetic wave at high frequency. A receiving rod antenna for converting into a high frequency receiving means, and a connector for guiding a high frequency received by the receiving rod antenna to high frequency receiving means, and the waveguide portion of the second flanged waveguide Guides the electromagnetic wave incident from the opening surface to the receiving rod antenna, and the flange of the second flanged waveguide causes the electromagnetic wave transmitted through the dielectric to pass through the dielectric from a position other than the opening surface. It is characterized by being configured to prevent leakage to the outside.
[0016]
A non-destructive measuring apparatus for complex permittivity according to claim 9 of the present application is the apparatus according to claim 6, 7 or 8 , wherein the reflection / transmission coefficient calculation means uses the Helmholtz equation derived from Maxwell's equation as the first and Couplings obtained by an exact solution that stands for each region of the second flanged waveguide and the dielectric and substitutes them into the boundary condition equation on the opening surface and flange surface of the flanged waveguide. The equation includes not only the fundamental mode but also higher-order modes generated at two apertures, and calculates the reflection coefficient and transmission coefficient of the fundamental mode.
[0017]
A non-destructive measuring apparatus for complex permittivity according to claim 10 of the present application is the complex permittivity and reflection coefficient calculated by the reflection / transmission coefficient calculating means according to claim 6, 7, 8 or 9 , wherein Using the correspondence relationship between the coefficient and the complex dielectric constant and the transmission coefficient, the complex dielectric constant is obtained directly from the absolute value and phase angle of the reflection coefficient and transmission coefficient obtained by the reflection / transmission coefficient measuring means.
[0018]
The non-destructive measuring apparatus for complex dielectric constant according to claim 11 of the present application is the complex dielectric constant and dielectric loss tangent (tan δ) according to claim 10 from the absolute value and phase angle of the reflection coefficient and transmission coefficient obtained from the sample to be measured. It is characterized by having a computer that calculates.
[0019]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of a non-destructive measurement method and apparatus for complex permittivity according to the present invention will be described below with reference to the drawings.
[0020]
FIG. 1 is a block diagram showing an embodiment of a non-destructive measurement method and apparatus for complex permittivity according to the present invention, and a signal transmission / reception terminal 11 and a signal of a reflection / transmission characteristic measurement apparatus 1 as a reflection / transmission coefficient measurement means. The dielectric insert 2 is connected between the receiving terminals 12. As the reflection / transmission characteristic measuring apparatus 1, a vector network analyzer often used for this kind of measurement is used. The vector network analyzer includes a sweep frequency oscillator, a level detector, a calibration circuit, and the like. The measurement result is displayed on the display on the reflection / transmission characteristic measurement device 1 and is output to the processing device 3 via the data output terminal 13. As the processing device 3, a computer such as a personal computer and peripheral devices such as a printer can be connected as necessary. Based on the measurement result of the reflection coefficient and the transmission coefficient displayed on the display unit or the result of processing by the processing device, the reflection / transmission characteristics (that is, reflection) of the dielectric that is the sample to be measured inserted in the dielectric insertion part 2 The absolute value and phase angle of the coefficient and transmission coefficient).
[0021]
In measuring the reflection coefficient and the transmission coefficient, the oscillation frequency range of the sweep oscillator of the vector network analyzer is set so as to include the frequency to be measured. The value of the complex dielectric constant can be obtained by directly reading the absolute values (magnitudes) and phase angles of the reflection coefficient and transmission coefficient displayed on a display or recorded by a printer, and using a method described later. In addition, it is preferable to use a complex permittivity specifying unit that computerizes the process according to the method and executes the process by a computer.
[0022]
FIG. 2 shows an electromagnetic wave input means including the first flanged waveguide 23 in the dielectric insertion part 2 of FIG. The flanged waveguide 23 includes a waveguide portion 24 and a flange 25. The waveguide portion 24 is supplied with a high frequency from the reflection / transmission characteristic measuring apparatus 1 which also functions as a high frequency generation means. Alternatively, a connector 21 for connecting a cable for sending a high frequency to the reflection / transmission characteristic measuring apparatus 1 is provided, and an electromagnetic wave is generated or received from the high frequency inputted from the connector 21. A rod antenna 22 is provided in the waveguide section 24 for converting the signal into a high frequency and outputting it to the connector 21. The connector 21 is connected to the signal transmission / reception terminal 11 of the reflection / transmission characteristic measuring apparatus 1 via a cable. The waveguide section 24 of the flanged waveguide 23 propagates the electromagnetic wave generated by the rod antenna 22 to the dielectric surface of the sample to be measured, and the fundamental of the reflected waves from the opening surface of the waveguide section 24. Only the mode is propagated to the rod antenna 22, and the flange 25 of the flanged waveguide 23 prevents the electromagnetic wave incident on the inside of the dielectric from leaking outside the dielectric from a position other than the opening surface. It is.
[0023]
FIG. 3 shows a configuration example of the dielectric insertion part 2. The dielectric insertion part 2 includes electromagnetic wave input means having a first flanged waveguide 23 and electromagnetic wave output means having a second flanged waveguide 33, and the first and second flanges. The

waveguides

23 and 33 have a structure in which the center axes of the

waveguides

23 and 33 coincide with each other to sandwich the front and back of a flat plate-like dielectric 40 that is a sample to be measured.
[0024]
The electromagnetic wave output means is configured to measure the electromagnetic wave transmitted through the dielectric 40 and is provided in the waveguide portion 34 of the second flanged waveguide 33 including the waveguide portion 34 and the flange 35. A receiving rod antenna 32 for converting the electromagnetic wave into a high frequency, and a connector 31 for guiding the high frequency received by the receiving rod antenna 32 to the reflection / transmission characteristic measuring apparatus 1 as a high frequency receiving means. The waveguide section 34 of the second flanged waveguide 33 guides the electromagnetic wave incident from the opening surface to the receiving rod antenna 32, and the flange of the second flanged waveguide 33. 35 prevents the electromagnetic wave transmitted through the dielectric 40 from leaking to the outside of the dielectric from a position other than the opening surface. The connector 31 is connected to the signal receiving terminal 12 via a cable.
[0025]
In the figure, the connecting portion between the dielectric insertion part 2 and the reflection / transmission characteristic measuring apparatus 1 is a connector. However, if the circuit format of the signal transmission / reception terminal of the reflection / transmission characteristic measuring apparatus 1 is a waveguide, If it is directly connected by a flange and is coaxial, a connector as shown in FIGS. 2 and 3 is used.
[0026]
Then, the dielectric 40 as the sample to be measured is inserted and pressed between the two

flanged waveguides

23 and 33 of the dielectric insertion part 2, and a certain frequency or from the opening surface of the one waveguide 23 is inserted. The reflection coefficient and the transmission coefficient when an electromagnetic wave having a frequency range that can be propagated through the waveguide is incident are measured by the reflection / transmission characteristic measuring apparatus 1, and the absolute values of the reflection coefficient and the transmission coefficient obtained by the measurement are measured. From the phase angle, the complex permittivity of the dielectric 40 is obtained by the processing device 3. If necessary, the processing device 3 is configured to be able to execute an operation for obtaining a complex dielectric constant and a dielectric loss tangent (tan δ) from the absolute values and phase angles of the reflection coefficient and the transmission coefficient by a calculation process by a computer. To do.
[0027]
The frequency characteristic of the complex dielectric constant of the dielectric 40 can be obtained by changing the frequency of the incident electromagnetic wave in the frequency range that can be propagated through the waveguide 23 with the sweep frequency oscillator of the vector network analyzer.
[0028]
The reflection coefficient Γ and the transmission coefficient T at the opening surface of the flanged waveguide due to the structure of the dielectric insertion part 2 represent the electromagnetic field in the waveguide and in the dielectric derived from Maxwell's equations, and the incident side and the transmission side. Boundary Conditional Equation for Waveguide Aperture (1)
[0029]
[Expression 1]

The following simultaneous equations (2) derived by substituting these into C ₁₀ (= Γ) and F ₁₀ (= T) are obtained by combining them.
[0030]
[Expression 2]

[0031]
[Equation 3]

[0032]
[Expression 4]

[0033]
[Equation 5]

[0034]
[Formula 6]

[0035]
[Expression 7]

[0036]
[Equation 8]

[0037]
[Equation 9]

[0038]
[Expression 10]

[0039]
## EQU11 ##

[0040]
[Expression 12]

[0041]
[Formula 13]

[0042]
[Expression 14]

[0043]
[Expression 15]

[0044]
[Expression 16]

[0045]
[Expression 17]

[0046]
[Formula 18]

[0047]
[Equation 19]

[0048]
[Expression 20]

[0049]
[Expression 21]

[0050]
[Expression 22]

[0051]
With the reflection / transmission characteristic measuring apparatus 1 of FIG. 1, the reflection coefficient Γ and the transmission coefficient T are measured, and the values are substituted into the simultaneous equations (2) and solved, whereby the complex of the dielectric 40 as the sample to be measured is calculated. The real part ε _r ′ and the imaginary part ε _r ″ of the dielectric constant are respectively obtained. The simultaneous equations (2) are derived from the Helmholtz equation derived from the Maxwell equation, and the first and second flanged derivatives are derived. This is a simultaneous equation obtained by an exact solution that stands for each region of the

wave tubes

23 and 33 and the dielectric 40 and substitutes them into the boundary condition equation on the opening surface and flange surface of each flanged waveguide.
[0052]
As described above, in the present invention, the complex dielectric constant is obtained by measuring the reflection coefficient Γ and the transmission coefficient T of the aperture surface. These measurements are performed when the aperture surface is short-circuited with a short-circuit plate and when a dielectric is inserted. Or the complex dielectric constant based on the two types of coefficients, reflection and transmission, when the two flanged waveguide openings are joined to each other and when a dielectric is inserted. Therefore, the accuracy of the complex permittivity is high, so that the complex permittivity can be measured accurately.
[0053]
The principle operation of the embodiment of the present invention shown in FIG. 1 has been described above. Next, the dielectric insertion part 2 shown in FIG. 3 will be described in detail. First, as the lengths ι ₁ and ι ₃ of the

waveguides

23 and 33 become longer, the transmission loss between the

rod antennas

22 and 32 and the opening surface becomes larger, so that the reflection coefficient Γ and the transmission coefficient T are required with the required accuracy. may be any length that can be measured, for example, in the case of waveguides X band (8.2~12.4GHz) it is, iota _1, may be iota ₃ = 10 cm approximately. Next, the dimensions a and b of the waveguide cross section are set to the rated dimensions a = 22.9 mm and b = 10.2 mm of a commonly used X-band rectangular waveguide. Since this dimension is a rating determined so as to suppress the propagation of higher-order modes unnecessary for measurement, it can be directly applied to this measurement method.
[0054]
In addition, the dimension ι ₂ of the flange and the dielectric is infinite in order to satisfy the radiation condition when deriving the formula (1). However, it is sufficient that the electromagnetic wave is sufficiently attenuated before reaching the end of the dielectric. Hirano et al. “Measurement of Complex Permittivity of Loss Dielectric Using Flange Rectangular Waveguide”, pp. 642-649, Nov. In view of the results of studies in 1999, the IEICE Transactions, it is sufficient that ι ₂ = 15 to 20 cm.
[0055]
Next, in the embodiment of the present invention, a high-order mode is generated on the opening surface due to the structure. These high-order mode reflected waves and high-order mode transmitted waves reach the rod antenna. In the reflection / transmission characteristic measuring apparatus 1, only the fundamental mode reflected wave and the higher-order mode transmitted wave on the aperture surface are observed. However, when calculating the reflection coefficient Γ and the transmission coefficient T using the equation (1), it is necessary to include the above-mentioned higher-order mode. Hirano et al., “Electromagnetic field analysis in a lossy dielectric body sandwiched between a rectangular waveguide with a flange and a conductor plate”, pp. 199. 525-536, Sep. 1999, in view of the results of studies in the IEICE Transactions, accurate reflection coefficients can be obtained by including 6 modes of TE ₁₀ , TE ₃₀ , TE ₁₂ , TM ₁₂ , TE ₁₄ , and TM _{14 in} the calculation. It is clear.
[0056]
Next, a method for inserting a dielectric material into the dielectric insertion portion 2 in FIG. 3 will be described. The dielectric 40 of the sample to be measured may be anything as long as it is a flat plate-like dielectric that can be sandwiched between two flanges. Then, the dielectric 40 is placed on the opening surface of one flanged waveguide 23, and the other flanged waveguide 33 is pressed against the dielectric surface from above to perform measurement. At this time, the positions of the opening surfaces of the two

flanged waveguides

23 and 33 must match. Moreover, it is preferable to make it closely_contact | adhere so that the clearance gap between air may not arise between a flange and a dielectric material. This is because it is not necessary to consider the difference in the complex dielectric constant and the difference in the thickness d of the dielectric due to the formation of the air layer. Therefore, it is necessary to hold the flanged waveguide against the dielectric surface with a certain amount of force, but the reflection coefficient Γ does not change even if it is pressed too strongly, so that there is no gap.
[0057]
As described above, the embodiment in which the dielectric insertion portion 2 is configured by the rectangular waveguide that is most popular as the transmission line of the microwave band and the millimeter wave band has been described in detail, but the circular waveguide and the coaxial waveguide are also described. Obviously, the same applies.
[0058]
In the measurement using the conventional waveguide, it is necessary to prepare a sample piece that is in close contact with the tube wall, which is troublesome. In addition, the dimensional accuracy is not a big problem in the X band of the present embodiment, but in the millimeter wave band where the frequency is higher, the size of the sample piece is as small as several millimeters, so a slight dimensional error may occur. It greatly affects the complex permittivity. For this reason, the present invention which does not require processing and accuracy of the sample piece is advantageous compared to the conventional method.
[0059]
Although the embodiments of the present invention have been described above, it will be obvious to those skilled in the art that the present invention is not limited to these embodiments, and various modifications and changes can be made within the scope of the claims.
[0060]
【The invention's effect】
As described above, according to the present invention, a plate-shaped dielectric having an arbitrary width may be used as a sample without requiring precision processing of the sample according to the dimensions of the measuring instrument, and the surface of the dielectric may be used. The complex permittivity can be easily measured simply by pressing the flanged waveguide. In addition, by covering the opening or flange surface of the waveguide with a dielectric having a known complex dielectric constant, not only solids but also liquids and gases can be used as high-temperature or corrosive media. Also has the effect of being able to measure.
[Brief description of the drawings]
FIG. 1 is a block diagram showing an embodiment of a complex dielectric constant nondestructive measurement method and apparatus according to the present invention.
FIG. 2 is a perspective view showing an electromagnetic wave input means in the dielectric insertion part in the embodiment.
FIG. 3 is a cross-sectional view showing a configuration example of a dielectric insertion part in the embodiment.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Reflection / transmission characteristic measuring apparatus 2

Dielectric insertion part

21, 31

Connector

22, 32

Rod antenna

23, 33

Waveguide

24, 34 with

flange Waveguide part

25, 35 Flange 40 Dielectric

Claims

A flat plate-shaped dielectric material, which is a sample to be measured, is inserted between two flanged waveguides and pressed so as to be in close contact with each other without any gaps. It has a dimension that attenuates enough to reach the end of
Measure the reflection coefficient and transmission coefficient when an electromagnetic wave of a certain frequency is incident from the opening surface of one of the waveguides,
The Helmholtz equation derived from Maxwell's equation is established for each of the two flanged waveguides and the dielectric region, and these are expressed as boundary condition equations on the opening surface and flange surface of each flanged waveguide. Using simultaneous equations obtained by the exact solution of substituting
Absolute value and the phase angle, non-destructive method of measuring a complex dielectric constant and obtaining the complex dielectric constant of the inserted dielectric reflection and transmission coefficients obtained by the measurement.

A flat plate-shaped dielectric material, which is a sample to be measured, is inserted between two flanged waveguides and pressed so as to be in close contact with each other without any gaps. It has a dimension that attenuates enough to reach the end of
Measure the reflection coefficient and transmission coefficient when an electromagnetic wave in a frequency range that can be propagated through the waveguide is incident from the opening surface of one of the waveguides,
The Helmholtz equation derived from Maxwell's equation is established for each of the two flanged waveguides and the dielectric region, and these are expressed as boundary condition equations on the opening surface and flange surface of each flanged waveguide. Using simultaneous equations obtained by the exact solution of substituting
Absolute value and the frequency characteristic of the phase angle, non-destructive method of measuring a complex dielectric constant and obtaining the frequency characteristics of the complex dielectric constant of the inserted dielectric reflection and transmission coefficients obtained by the measurement.

The operation for obtaining a complex dielectric constant and a dielectric loss tangent (tan δ) from the absolute values and phase angles of the reflection coefficient and the transmission coefficient obtained from the sample to be measured is performed by a calculation process by a computer. 3. The nondestructive measurement method of complex dielectric constant according to 2.

A flat plate-shaped dielectric material, which is a sample to be measured, is inserted between two flanged waveguides and pressed so as to be in close contact with each other without any gaps. It has a dimension that attenuates enough to reach the end of
Measure the reflection coefficient and transmission coefficient of the opening surface of one of the waveguides with a reflection / transmission coefficient measuring means,
Helmholtz equations derived from Maxwell's equations are established for each of the two flanged waveguides and the dielectric regions, and these are defined as boundary condition equations on the opening surface and flange surface of the respective flanged waveguides. Using simultaneous equations obtained by the exact solution of substituting
Absolute value and the phase angle, non-destructive measurement device of the complex dielectric constant, characterized in that to determine the complex dielectric constant of the inserted dielectric a dielectric constant specifying means of the reflection and transmission coefficients obtained by the measurement.

Insert a flat plate-shaped dielectric material as a sample to be measured between two flanged waveguides and hold them so that they are in close contact with each other, and make electromagnetic waves incident from the opening surface of one of the flanged waveguides. The electromagnetic wave incident on the dielectric from the surface does not leak to the outside of the dielectric from a position other than the opening surface of each flanged waveguide, and is therefore adversely affected by electromagnetic waves from outside the measurement system. Without measuring the reflection coefficient and transmission coefficient with the reflection / transmission coefficient measuring means,
The Helmholtz equation derived from Maxwell's equation is established for each of the two flanged waveguides and the dielectric region, and these are expressed as boundary condition equations on the opening surface and flange surface of each flanged waveguide. Using simultaneous equations obtained by the exact solution of substituting
Absolute value and the phase angle, non-destructive measurement device of the complex dielectric constant, characterized in that to determine the complex dielectric constant of the inserted dielectric a dielectric constant specifying means of the reflection and transmission coefficients obtained by the measurement.

An electromagnetic wave is incident on the surface of a flat plate-shaped dielectric material, which is a sample to be measured, from the opening surface, and the first flanged waveguide for measuring the reflected wave from the opening surface is provided. Electromagnetic wave input means for closely attaching the flange of the flanged waveguide to the surface of the dielectric without gaps;
An electromagnetic wave output means having a second flanged waveguide for measuring the electromagnetic wave transmitted through the dielectric, and the flange of the second flanged waveguide is in close contact with the opposite surface of the dielectric without any gap When,
Supplying electromagnetic waves to the electromagnetic wave input means, measuring the reflection characteristics of the inserted dielectric with respect to the fundamental mode, receiving electromagnetic waves from the electromagnetic wave output means, and transmitting the dielectric with respect to the fundamental mode Reflection / transmission coefficient measurement means for measuring
The Helmholtz equation derived from Maxwell's equation is established for each of the two flanged waveguides and the dielectric region, and these are expressed as boundary condition equations on the opening surface and flange surface of each flanged waveguide. Using simultaneous equations obtained by the exact solution of substituting
In order to obtain the complex dielectric constant of the dielectric from the reflection characteristic and transmission characteristic measured by the reflection / transmission coefficient measuring means, the reflection coefficient and the reflection / transmission coefficient for calculating the relationship between the transmission coefficient and the complex dielectric constant. A calculation means;
A complex dielectric comprising: a dielectric constant specifying means for specifying the complex dielectric constant of the dielectric from the relationship between the reflection coefficient and the transmission coefficient calculated by the reflection / transmission coefficient calculation means and the complex dielectric constant Rate non-destructive measuring device.

The electromagnetic wave input means includes a connector for guiding the high frequency generated by the high frequency generation means to the waveguide portion of the first flanged waveguide, and for converting the high frequency into an electromagnetic wave in the waveguide portion. A rod antenna, and the waveguide portion of the first flanged waveguide guides the electromagnetic wave radiated from the rod antenna to the opening surface thereof to enter the dielectric, and The complex dielectric constant nondestructive measurement according to claim 6, wherein the flange of the flanged waveguide is configured to prevent electromagnetic waves incident on the inside of the dielectric from leaking to the outside of the dielectric from a position other than the opening surface. apparatus.

The electromagnetic wave output means is provided in the waveguide portion of the second flanged waveguide, receives a receiving rod antenna for converting electromagnetic waves into a high frequency, and receives a high frequency received by the receiving rod antenna. A connector for guiding to the receiving means, the waveguide portion of the second flanged waveguide guides the electromagnetic wave incident from the opening surface thereof to the receiving rod antenna, and The non-destructive measurement of a complex dielectric constant according to claim 6 or 7, wherein the flange of the flanged waveguide is configured to prevent electromagnetic waves transmitted through the dielectric from leaking to the outside of the dielectric from a position other than the opening surface. apparatus.

The reflection / transmission coefficient calculation means sets Helmholtz equations derived from Maxwell's equations for the first and second flanged waveguides and the dielectric regions, and sets the Helmholtz equations with the flanges. The simultaneous equations obtained by the rigorous method of substituting into the boundary condition equations on the opening and flange surfaces of the waveguide include not only the fundamental mode but also higher-order modes generated at the two opening surfaces. 9. The non-destructive measuring apparatus for complex permittivity according to claim 6, 7 or 8, wherein a mode reflection coefficient and a transmission coefficient are calculated.

The dielectric constant specifying means uses the correspondence between the complex dielectric constant and the reflection coefficient calculated by the reflection / transmission coefficient calculation means and the complex dielectric constant and the transmission coefficient, and the reflection coefficient obtained by the reflection / transmission coefficient measurement means. 10. The non-destructive measuring apparatus for complex permittivity according to claim 6, 7, 8 or 9, wherein the complex permittivity is directly obtained from the absolute value of the transmission coefficient and the phase angle.

11. A non-destructive complex permittivity according to claim 10, further comprising a computer for calculating a complex permittivity and a dielectric loss tangent (tan δ) from the absolute values and phase angles of the reflection coefficient and the transmission coefficient obtained from the sample to be measured. measuring device.