JP3753296B2

JP3753296B2 - Radio hologram observation device

Info

Publication number: JP3753296B2
Application number: JP16648599A
Authority: JP
Inventors: 均北吉
Original assignee: Advantest Corp
Current assignee: Advantest Corp
Priority date: 1999-06-14
Filing date: 1999-06-14
Publication date: 2006-03-08
Anticipated expiration: 2019-06-14
Also published as: JP2000356661A

Description

【０００１】
【発明の属する技術分野】
この発明は、２入力干渉観測法により電波ホログラムを観測する装置に関する。
【０００２】
【従来の技術】
この発明者は特開平１１−６５４０６号「円周走査型ホログラム観測方法及び装置」を提案した。これは図６に示すように固定アンテナＡｒと円周回転走査アンテナＡｍとを用いて回転走査アンテナＡｍをモータＭにより回転させ、アンテナＡｍの受信信号をロータリージョイントＪ_Rを介して受信機Ｒｍで受信し、固定アンテナＡｒよりの受信信号を受信機Ｒｒで受信し、これら受信機Ｒｍ、Ｒｒは設定された観測周波数ｆの信号を選出し、それぞれ増幅し、中間周波信号Ｓｒ（ｆ）、Ｓｍ（φ，ｆ）（φは方位角）として出力し、これら信号Ｓｒ（ｆ）、Ｓｍ（φ，ｆ）を干渉器１１に入力して互に干渉させ、∫Ｓｒ^*（ｆ）・Ｓｍ（φ，ｆ）（＊は複素共役を表わす）を得、これを複素検波器１２で検波して測定データＥ（φ）を得る。このデータをバッファメモリ２１に走査アンテナＡｍの回転角（水平方位角）φについて記憶し、その記憶結果について演算、表示部２２でホログラム再生演算を行い、その演算結果を表示する。
【０００３】
このようにしてホログラム測定を行うことにより、死角がなく３６０°全部を視野角とすることができる。
【０００４】
【発明が解決しようとする課題】
この提案した装置ではアンテナを機械的回転走査するものであるため、高速にホログラム観測をすることができない。
また不安定な反射回折波などの影響を受ける。
この発明の第１の目的は高速にホログラム観測を行うことができる電波ホログラム観測装置を提供することにある。
【０００５】
この発明の第２の目的はフェージングに対して安定な測定を可能とするホログラム観測装置を提供することにある。
【０００６】
【課題を解決するための手段】
この発明によればリング状アレーアンテナの各アンテナ素子の受信信号の少くとも１つを選択する複数のアンテナ選択手段と、受信信号を複数の受信機の何れかに供給する複数の受信機選択手段とが縦続的に設けられて、選択されたアンテナ素子の受信信号が複数の受信機の選択された１つへ供給され、これら受信機の出力の１つを基準として他の受信機の出力とが干渉され、受信信号の干渉が観測される。
【０００７】
基準となる出力の受信機には複数のアンテナ素子の受信信号が合成され、合成指向性パタンとして受信される。その合成指向性パタンの主ビームは電波到来方向とし、ヌルの方向は反射波、干渉波到来方向となるようにする。
基準となる出力の受信機へのアンテナ素子受信信号の選択供給を固定し、他の受信機へのアンテナ素子受信信号の選択を順次切替えて受信信号の干渉を観測する。
【０００８】
【発明の実施の形態】
この発明においてはアレーアンテナが用いられ、その各アンテナ素子は２つ以上のグループごとにアンテナ選択手段により選択される。例えば図１に示すようにアンテナ素子Ａ１〜Ａ２４が水平面内で等間隔でリング状に配され、各アンテナ素子Ａ１〜Ａ２４は半波長ダイポールアンテナであって、垂直方向（紙面と直角に）に延長されている。
【０００９】
これらアンテナ素子Ａ１〜Ａ２４は図２に示す例では、３つのグループに分けられた場合で、配列方向において各アンテナ素子Ａ１〜Ａ２４が順番に入力選択スイッチ付きウイルキンソン形電力合成器ＳＨ１〜ＳＨ３に１つずつ順次接続することが繰返されて３つのグループに分けられる。入力選択スイッチ付きウイルキンソン形電力合成器ＳＨ１〜ＳＨ３はそれぞれ入力選択信号により指定され、任意の数の入力信号の電力を合成する。ウイルキンソン形電力合成器ＳＨ１〜ＳＨ３の各出力はそれぞれスイッチＳ１〜Ｓ３により、入力選択スイッチ付きウイルキンソン形電力合成器ＳＨｒ，ＳＨｍの何れかに切替え入力される。これら電力合成器ＳＨｒ，ＳＨｍの各出力はそれぞれ受信機Ｒｒ，Ｒｍに入力される。
【００１０】
電力合成器ＳＨ１〜ＳＨ３はそれぞれアンテナ素子を選択するアンテナ選択手段を構成し、スイッチＳ１〜Ｓ３は受信機Ｒｒ，Ｒｍの何れかを選択する受信機選択手段を構成し、電力合成器ＳＨｒ，ＳＨｍはグループ分けしたアンテナ素子のグループを選択するグループ選択手段を構成している。アンテナ選択手段、受信機選択手段、グループ選択手段を用いて、各グループ間のアンテナ受信信号の干渉観測を行う。
【００１１】
つまり受信機Ｒｒ，Ｒｍにおいて、任意の中心周波数、及び任意の周波数帯域幅で受信信号の選択と周波数変換を行って中間周波信号として出力すると共に、基準となる受信機の出力中間周波信号の平均レベル（振幅）を検出する。これら受信機Ｒｒ，Ｒｍとしては例えばスペクトラムアナライザをゼロスパンモードで動作させて実現することができる。これら出力中間周波信号は干渉器１１に入力される。干渉器１１では２つの入力信号のクロススペクトラムの周波数積分結果を一定周波数の線スペクトルとして出力する。この干渉器１１の詳細は例えば特開平９−１３３７２１号「相関関数測定方法及び装置」に示されている。受信機Ｒｒ，Ｒｍにそれぞれ入力された受信信号が得られたアンテナ素子の番号をＫ，Ｌとし、受信周波数をｆとし、受信機Ｒｒ，Ｒｍの各出力をＳｒ（Ｋ，ｆ），Ｓｍ（Ｌ，ｆ）と表わすと、干渉器１１の出力は∫Ｓｒ^*（Ｋ，ｆ）・Ｓｍ（Ｌ，ｆ）ｄｆとなる。＊は複素共役を表わす。
【００１２】
干渉器１１の出力線スペクトルの振幅と位相が検波器１２で検出される。その検出された複素振幅ν₀（Ｋ，Ｌ）はレベル校正器１３で、受信機Ｒｒよりの検出平均信号レベルν_R（Ｋ）により正規化され、測定データＥ（Ｋ，Ｌ）＝ν₀（Ｋ，Ｌ）／ν_R（Ｋ）が得られる。この測定データＥ（Ｋ，Ｌ）は複素数である。このようにして２つのグループ中の各選択したアンテナ素子の受信信号間の干渉信号が得られる。
【００１３】
いま図１において、アンテナ素子Ａ５の方向から直接波が到来し、アンテナ素子Ａ３の方向から不安定な反射波（車両などからの反射によるもので時間的に変化する）が到来している場合のホログラム観測方法を以下に述べる。
（１）受信機選択スイッチＳ１を受信機Ｒｍ側に、スイッチＳ２をＲｒ側に、スイッチＳ３をＲｍ側にそれぞれ接続する。
（２）アンテナ選択手段により、電力合成器ＳＨ２においてアンテナ素子Ａ２，Ａ５，Ａ８を接続し、他の全てのアンテナ素子は断とする。これにより受信機Ｒｒの入力としてＳｒ′（２＋５＋８，ｆ）が得られる。
（３）アンテナ選択手段により、Ｒｍ側に接続された電力合成器ＳＨ１，ＳＨ３において、アンテナ素子を順次１個づつ選択接続して、受信機Ｒｍに受信信号Ｓｍ′（１，ｆ），Ｓｍ′（３，ｆ），Ｓｍ′（４，ｆ），・・・，Ｓｍ′（２４，ｆ）を順次入力させ、これらと前記受信機Ｒｒの受信信号Ｓｒ′（２＋５＋８，ｆ）とを順次干渉させ、レベル校正器１３からＳｒ′（２＋５＋８，ｆ）を基準とした測定データＥ（２＋５＋８，１），Ｅ（２＋５＋８，３），Ｅ（２＋５＋８，４），・・・，Ｅ（２＋５＋８，２４）を得る。
（４）受信機選択手段のＳ１を受信機Ｒｒ側に、Ｓ２を受信機Ｒｍ側に、Ｓ３を受信機Ｒｒ側にそれぞれ切替える。
（５）アンテナ選択手段により受信機Ｒｒ側に接続された電力合成器ＳＨ１，ＳＨ３でアンテナ素子Ａ３，Ａ４，Ａ６，Ａ７をそれぞれ接続し、他の全てのアンテナ素子を断にする、これにより受信機Ｒｒに受信信号Ｓｒ′（３＋４＋６＋７，ｆ）が入力される。
（６）受信機Ｒｍ側に接続された電力合成器ＳＨ２のアンテナ素子を順次１個づつ接続して、受信機Ｒｍに受信信号Ｓｍ′（２，ｆ），Ｓｍ′（５，ｆ），Ｓｍ′（８，ｆ），・・・，Ｓｍ′（２３，ｆ）を入力する。これらを先に受信した受信機Ｒｒの信号Ｓｒ′（３＋４＋６＋７，ｆ）とそれぞれ干渉させて、Ｓｒ′（３＋４＋６＋７，ｆ）を基準とした測定データＥ（３＋４＋６＋７，２），Ｅ（３＋４＋６＋７，５），Ｅ（３＋４＋６＋７，８），・・・，Ｅ（３＋４＋６＋７，２３）をレベル校正器１３から得る。
（７）アンテナ選択手段で受信機Ｒｍに接続された電力合成器ＳＨ２においてアンテナ素子２Ａ，５Ａ，８Ａを同時に接続して、受信機Ｒｍに受信信号Ｓｍ′（２＋５＋８，ｆ）を入力し、これと受信信号Ｓｒ′（３＋４＋６＋７，ｆ）とを干渉させてＳｍ′（３＋４＋６＋７，ｆ）を基準としたこれとＳｍ′（２＋５＋８，ｆ）との干渉により得られるデータＥ（３＋４＋６＋７，２＋５＋８）をレベル校正器１３から得る。
（８）ステップ（３）で得られたレベル校正器１３の出力を全て、ステップ（７）で得られたレベル校正器１３の出力で位相を正規化する、つまりＳｒ′（３＋４＋６＋７，ｆ）の位相を位相基準とする。例えばＥ（２＋５＋８，１）については下記の演算を行う。
【００１４】
Ｅ(1) ＝（Ｅ（２＋５＋８，１）／Ｅ（３＋４＋６＋７，２＋５＋８））・｜Ｅ（３＋４＋６＋７，２＋５＋８）｜
またステップ（６）で得られたレベル校正器１３の出力Ｅについては位相基準はＳｒ′（３＋４＋６＋７，ｆ）であるから、例えば
Ｅ(2) ＝Ｅ（３＋４＋６＋７，２)
とするように、そのまま用いる。このようにしてＥ(1) 〜Ｅ(24)のすべてが共通の位相基準となる。
（９）ステップ（８）で得られたＥ(1) ，Ｅ(2) ，・・・，Ｅ(24)を用いてホログラム再生処理を行う。例えば以下の演算を行う。
【００１５】
φ＝ｎπ／１２，φ′＝ｎ′π／１２
Ｗ（φ）＝（１／π）（１＋ cos（２φ））（重み付け関数）
リング状アレーアンテナの半径をｒ、観測電波の波長をλ、到来波の仰角θを考慮した等価半径をｒ′（ｒ′＝ｒ sinθ）とすると評価関数Ｖ（φ′）＝∫Ｗ（φ） exp（−ｊ２πｒ′cos φ／λ）・Ｅ（φ＋φ′）ｄφ ∫は−π／２からπ／２まで
から到来波の方向及び振幅値を求めることができる。つまりφ′を設定してその−π／２からπ／２の積分をしてＶ（φ′）を得ることを、φ′を順次変更して行い、ピークが得られたＶ（φ′）のφ′が到来方向であり、そのＶ（φ′）が振幅である。
【００１６】
ステップ（２）及び（５）における受信機Ｒｒでの受信においては、アンテナの指向性合成によって安定な直接波到来方向へ主ビームを向けて、不安定な反射波到来方向へビームのヌルを向けることによって、位相比較基準信号Ｓｒ（Ｋ，ｆ）の時間変動（マルチパス合成による位相ゆらぎ）を抑制している。図３Ａにアンテナ素子Ａ２，Ａ５，Ａ８の合成指向特性を、図３Ｂにアンテナ素子Ａ３，Ａ４，Ａ６，Ａ７の合成指向特性をそれぞれ示す。それぞれ主ビームの方向が直接波到来方向（アンテナ素子Ａ５の方向）となり、ヌルが反射波到来方向（アンテナ素子Ａ３の方向）となっている。
【００１７】
ステップ（７）及び（８）の処理は、上記２つのアンテナ指向性で測定される位相比較基準信号の位相差を求めて、一方を校正して同一位相基準でのホログラム観測結果を得ている。
これら位相比較基準信号を得るためのアンテナ指向性方向を回転走査しながらステップ（１）〜（９）の手順を繰返し行うことにより複数の到来方向の電波のホログラム像を観測することで混信・妨害波とマルチパスの分離評価が可能となる。混信・妨害波は上記走査で相対レベルが変化するが、マルチパスは相対レベルが変化しない。アンテナ指向性の走査は例えば、前記アンテナ素子Ａ２，Ａ５，Ａ８の選択とＡ３，Ａ４，Ａ６，Ａ７の選択の状態から、アンテナ素子Ａ３，Ａ６，Ａ９の選択と、Ａ４，Ａ５，Ａ７，Ａ８の選択状態として指向方向をアンテナ素子Ａ５からＡ６方向に切替えた状態でステップ（１）〜（９）を行い、以下同様にアンテナ指向方向を順次ずらしてステップ（１）〜（９）を行うことを繰返す。
【００１８】
次に、安定な直接波到来方向や不安定な反射波到来方向を見出す方法について述べる。
第１の方法は受信機選択スイッチＳ１，Ｓ２，Ｓ３を全て受信機Ｒｒ側として、任意のアンテナ素子選択の組み合せで最大受信レベルに近く、かつ時間的にレベルが安定したアンテナ選択手段におけるアンテナ素子選択組合せを見つける。通常はνｒ（ｎ１＋ｎ２＋ｎ３）として、アンテナ素子Ａｎ２に対し、Ａｎ１及びＡｎ３がそれぞれ隣り合うアンテナ素子となるように順次選択する。
【００１９】
第２の方法はステップ（１）〜（９）の操作において、受信機Ｒｒに接続されるアンテナ素子を適当に選択して、ホログラム観測を行い、この観測結果からレベルが大きく安定したパスを選択決定する。この方法では受信機Ｒｒに接続するアンテナ素子の組み合せの試行及び同一条件での複数回観測による時間変動評価が必要である。
【００２０】
このようにして直接波の到来方向及び不安定な反射波の到来方向を知り、主ビームが直接波到来方向に向き、ヌルが不安定反射波到来方向に向いた、アンテナ合成指向特性が得られるように、アンテナ素子を選択し、この選択したアンテナ素子組み合せの受信信号を位相基準としてステップ（１）〜（９）を行うことにより安定なホログラム観測が可能となる。
【００２１】
図２中の選択制御・演算・表示部１４において、ステップ（１）〜（９）を実行する上でのアンテナ選択、受信機選択の制御を行い、また安定な直接波や不安定な反射波の到来方向決定のためのアンテナ選択、受信機選択を行い、得られたデータＥ（Ｋ，Ｌ）についてステップ（８）の補正、ステップ（９）の演算を行い、その演算結果をφ′をパラメータとして表示することを行う。
【００２２】
アレーアンテナとしては円周ではなく任意の形状でもよい。例えば図４に示すように円周層状アレーアンテナとしてもよい。この場合はステップ（１）〜（９）を各層のアレーアンテナについて行ってデータＥ（φ，Ｚ）（Ｚは何番目の層であるかを示す）を求め、このＥ（φ，Ｚ）をＺに対してフーリエ変換し、その変換結果Γ（φ，Ψ）（Ψは仰角）に対し、θ＝π／２−Ψとおいて
Ｖ（φ′，θ）＝∫Ｗ（φ）exp （−ｊ２πｒ sinθcos φ／λ）Γ（φ＋φ′，θ）ｄφ
∫は−π／２からπ／２まで
を求めてホログラム再生像を求める。このようにすれば１つのφ′に対し１つのθについて計算すればよく、計算量が少なくて済む。
【００２３】
上述ではアンテナ素子を選択した後、その選択したアンテナ素子をどの受信機に接続するかの受信機選択を行った。しかし、まず接続する受信機を選択した後、アンテナ素子の選択を行うようにしてもよい。例えば図５に示すように、各アンテナ素子Ａ１〜Ａ２４ごとに受信機選択スイッチＳ１〜Ｓ２４により受信機Ｒｒ、Ｒｍの何れに受信信号を供給するかの選択をそれぞれ行い、スイッチＳ１〜Ｓ２４の各受信機Ｒｒ側の切替え接点ｒ側を入力選択スイッチ付きウイルキンソン形電力合成器ＳＨｒに接続し、スイッチＳ１〜Ｓ２４の各受信機Ｒｍ側の切替え接点ｍ側を入力選択スイッチ付きウイルキンソン形電力合成器ＳＨｍに接続する。電力合成器ＳＨｒで基準の合成指向特性パタンが得られるようにアンテナ素子を選択して、その受信信号を受信機Ｒｒへ供給する。また電力合成器ＳＨｍで各アンテナ素子を順次選択してその受信信号を受信機Ｒｍへ供給する。受信機Ｒｒの出力を基準とし、これと、受信機Ｒｍの順次受信される各アンテナ素子の出力とを干渉器１１で干渉させること以後の処理は先の実施例と同様である。
【００２４】
この実施例よりも図２に示した実施例の方が使用するスイッチの数が少なくて済む特徴がある。なお図２において入力選択付きウイルキンソン形電力合成器ＳＨｒ、ＳＨｍを省略して、スイッチＳ１，Ｓ２，Ｓ３の各接点ｒ側を受信機Ｒｒの入力側に接続し、スイッチＳ１，Ｓ２，Ｓ３の各接点ｍ側を受信機Ｒｍの入力側に接続してもよい。つまりグループ選択は省略してもよい。ただし、電力合成器ＳＨｒ，ＳＨｍを省略すると、受信機Ｒｒ，Ｒｍにおいて各入力された信号が接続されていない接点側へゆき、反射して来たりして弊害が生じるおそれがあるが、電力合成器ＳＨｒ，ＳＨｍを用いて接続されているものだけを選択することにより、前記弊害をなくすことができる。
【００２５】
図２において、アンテナ素子のグループ分割数は３に限られるものでない。また図２、図５において受信機の数も３以上とし、１つの基準の受信機出力と、他の受信機出力との各干渉を求めるようにして、並列処理により、高速化するようにしてもよい。
【００２６】
【発明の効果】
この発明によればアレーアンテナのアンテナ素子の１乃至複数を基準受信信号とし、他のアンテナ素子をスイッチにより選択接続して、アンテナを等価的に回転させて各アンテナ素子の受信信号を上記基準受信信号と干渉させるものであるから、アンテナを機械的に回転させる場合より、高速に回転させることができ、それだけ短時間でホログラム観測を行うことができる。
【００２７】
アンテナ素子の複数を同時に選択して合成指向特性の主ビームの方向が直接波到来方向とすることにより、安定な測定が可能である。
更に前記合成指向特性のヌルが反射波や妨害波の方向となるようにすることにより不安定な反射波、混信・妨害波を分離し、これらの影響をなくすことができる。
【図面の簡単な説明】
【図１】Ａはこの発明装置に用いられるアレーアンテナの一例を示す平面図、ＢはそのＡＡ線断面図である。
【図２】この発明装置の機能的構成例を示すブロック図。
【図３】複数のアンテナ素子による合成指向特性の例を示す図。
【図４】アレーアンテナの他の例を簡略に示す図。
【図５】この発明の他の実施例の機能的構成を示すブロック図。
【図６】従来の電波ホログラム観測装置を示すブロック図。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an apparatus for observing a radio hologram by a two-input interference observation method.
[0002]
[Prior art]
This inventor proposed Japanese Patent Laid-Open No. 11-65406 “Circumferential Scanning Hologram Observation Method and Apparatus”. As shown in FIG. 6, the rotation scanning antenna Am is rotated by the motor M using the fixed antenna Ar and the circumferential rotation scanning antenna Am, and the reception signal of the antenna Am is received by the receiver Rm via the rotary joint _JR. The received signal from the fixed antenna Ar is received by the receiver Rr, and the receivers Rm and Rr select the signals of the set observation frequency f, amplify them, and intermediate frequency signals Sr (f) and Sm. (Φ, f) (φ is an azimuth angle) and these signals Sr (f), Sm (φ, f) are input to the interferor 11 to interfere with each other, and ∫Sr ^* (f) · Sm ( φ, f) (* represents a complex conjugate) is obtained, and this is detected by the complex detector 12 to obtain measurement data E (φ). This data is stored in the buffer memory 21 for the rotation angle (horizontal azimuth angle) φ of the scanning antenna Am, the stored result is calculated, the hologram reproduction calculation is performed by the display unit 22, and the calculation result is displayed.
[0003]
By performing hologram measurement in this way, there is no blind spot and the entire viewing angle can be 360 °.
[0004]
[Problems to be solved by the invention]
In this proposed apparatus, since the antenna is mechanically rotated and scanned, the hologram cannot be observed at high speed.
It is also affected by unstable reflected diffraction waves.
A first object of the present invention is to provide a radio wave hologram observation apparatus capable of performing hologram observation at high speed.
[0005]
A second object of the present invention is to provide a hologram observation apparatus that enables stable measurement against fading.
[0006]
[Means for Solving the Problems]
According to the present invention, a plurality of antenna selecting means for selecting at least one received signal of each antenna element of the ring array antenna, and a plurality of receiver selecting means for supplying the received signal to any one of the plurality of receivers. Are provided in cascade, and the received signal of the selected antenna element is supplied to a selected one of the plurality of receivers, and the output of the other receiver is set based on one of the outputs of these receivers. Are received, and interference of the received signal is observed.
[0007]
Reception signals of a plurality of antenna elements are combined into a reference output receiver and received as a combined directivity pattern. The main beam of the combined directivity pattern is the radio wave arrival direction, and the null direction is the reflected wave and interference wave arrival direction.
The selection and supply of the antenna element reception signal to the reference output receiver is fixed, and the selection of the antenna element reception signal to other receivers is sequentially switched to observe the interference of the reception signal.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
In the present invention, an array antenna is used, and each antenna element is selected by an antenna selection means for every two or more groups. For example, as shown in FIG. 1, antenna elements A1 to A24 are arranged in a ring shape at equal intervals in a horizontal plane, and each antenna element A1 to A24 is a half-wave dipole antenna and extends in the vertical direction (perpendicular to the paper surface). Has been.
[0009]
In the example shown in FIG. 2, these antenna elements A1 to A24 are divided into three groups, and each antenna element A1 to A24 is sequentially assigned to Wilkinson power combiners SH1 to SH3 with input selection switches in the arrangement direction. The sequential connection is repeated one by one and divided into three groups. Wilkinson power combiners SH1 to SH3 with input selection switches are each designated by an input selection signal and synthesize power of an arbitrary number of input signals. The outputs of the Wilkinson power combiners SH1 to SH3 are switched and input to any of Wilkinson power combiners SHr and SHm with input selection switches by switches S1 to S3, respectively. Outputs of these power combiners SHr and SHm are input to receivers Rr and Rm, respectively.
[0010]
The power combiners SH1 to SH3 constitute antenna selection means for selecting antenna elements, respectively. The switches S1 to S3 constitute receiver selection means for selecting one of the receivers Rr and Rm, and the power combiners SHr and SHm. Constitutes group selection means for selecting the grouped antenna elements. Interference observation of antenna reception signals between groups is performed using antenna selection means, receiver selection means, and group selection means.
[0011]
That is, in the receivers Rr and Rm, a received signal is selected and frequency-converted at an arbitrary center frequency and an arbitrary frequency bandwidth and output as an intermediate frequency signal, and an average of output intermediate frequency signals of a reference receiver. Detect level (amplitude). These receivers Rr and Rm can be realized, for example, by operating a spectrum analyzer in the zero span mode. These output intermediate frequency signals are input to the interferometer 11. The interferometer 11 outputs the frequency integration result of the cross spectrum of the two input signals as a line spectrum with a constant frequency. Details of the interferometer 11 are disclosed in, for example, Japanese Patent Laid-Open No. 9-133721 “Method and Apparatus for Measuring Correlation Function”. The numbers of the antenna elements from which the received signals input to the receivers Rr and Rm are obtained are K and L, the reception frequency is f, and the outputs of the receivers Rr and Rm are Sr (K, f) and Sm ( When expressed as L, f), the output of the interferometer 11 is ∫Sr ^* (K, f) · Sm (L, f) df. * Represents a complex conjugate.
[0012]
The detector 12 detects the amplitude and phase of the output line spectrum of the interferometer 11. The detected complex amplitude ν ₀ (K, L) is normalized by the level calibrator 13 by the detected average signal level ν _R (K) from the receiver Rr, and the measurement data E (K, L) = ν _0. (K, L) / ν _R (K) is obtained. The measurement data E (K, L) is a complex number. In this way, an interference signal between the received signals of each selected antenna element in the two groups is obtained.
[0013]
In FIG. 1, a direct wave comes from the direction of the antenna element A5, and an unstable reflected wave (changes in time due to reflection from a vehicle or the like) comes from the direction of the antenna element A3. The hologram observation method is described below.
(1) Connect the receiver selection switch S1 to the receiver Rm side, the switch S2 to the Rr side, and the switch S3 to the Rm side.
(2) The antenna selecting means connects the antenna elements A2, A5 and A8 in the power combiner SH2 and disconnects all other antenna elements. As a result, Sr ′ (2 + 5 + 8, f) is obtained as an input of the receiver Rr.
(3) In the power combiners SH1 and SH3 connected to the Rm side by the antenna selection means, the antenna elements are selected and connected one by one in order, and the received signals Sm ′ (1, f), Sm ′ are connected to the receiver Rm. (3, f), Sm ′ (4, f),..., Sm ′ (24, f) are sequentially inputted, and these are sequentially interfered with the received signal Sr ′ (2 + 5 + 8, f) of the receiver Rr. Then, measurement data E (2 + 5 + 8,1), E (2 + 5 + 8,3), E (2 + 5 + 8,4),..., E (2 + 5 + 8, 24) from the level calibrator 13 with Sr ′ (2 + 5 + 8, f) as a reference. )
(4) S1 of the receiver selection means is switched to the receiver Rr side, S2 is switched to the receiver Rm side, and S3 is switched to the receiver Rr side.
(5) The antenna elements A3, A4, A6, and A7 are connected by the power combiners SH1 and SH3 connected to the receiver Rr side by the antenna selection means, and all other antenna elements are disconnected. The reception signal Sr ′ (3 + 4 + 6 + 7, f) is input to the machine Rr.
(6) The antenna elements of the power combiner SH2 connected to the receiver Rm side are sequentially connected one by one, and the received signals Sm ′ (2, f), Sm ′ (5, f), Sm are connected to the receiver Rm. ′ (8, f),..., Sm ′ (23, f) are input. These are caused to interfere with the signal Sr ′ (3 + 4 + 6 + 7, f) of the receiver Rr previously received, and measured data E (3 + 4 + 6 + 7, 2), E (3 + 4 + 6 + 7, 5) based on Sr ′ (3 + 4 + 6 + 7, f). , E (3 + 4 + 6 + 7, 8),..., E (3 + 4 + 6 + 7, 23) are obtained from the level calibrator 13.
(7) In the power combiner SH2 connected to the receiver Rm by the antenna selection means, the antenna elements 2A, 5A and 8A are simultaneously connected, and the received signal Sm ′ (2 + 5 + 8, f) is input to the receiver Rm. And the received signal Sr ′ (3 + 4 + 6 + 7, f) are interfered with each other, and the level of the data E (3 + 4 + 6 + 7, 2 + 5 + 8) obtained by interference between Sm ′ (2 + 5 + 8, f) and Sm ′ (3 + 4 + 6 + 7, f) Obtained from the calibrator 13.
(8) All the outputs of the level calibrator 13 obtained in step (3) are normalized with the output of the level calibrator 13 obtained in step (7), that is, Sr ′ (3 + 4 + 6 + 7, f) Phase is used as a phase reference. For example, for E (2 + 5 + 8, 1), the following calculation is performed.
[0014]
E (1) = (E (2 + 5 + 8,1) / E (3 + 4 + 6 + 7,2 + 5 + 8)) · | E (3 + 4 + 6 + 7,2 + 5 + 8) |
For the output E of the level calibrator 13 obtained in step (6), the phase reference is Sr ′ (3 + 4 + 6 + 7, f), so that for example E (2) = E (3 + 4 + 6 + 7, 2)
As it is, it is used as it is. In this way, all of E (1) to E (24) become a common phase reference.
(9) Hologram reproduction processing is performed using E (1), E (2),..., E (24) obtained in step (8). For example, the following calculation is performed.
[0015]
φ = nπ / 12, φ ′ = n′π / 12
W (φ) = (1 / π) (1 + cos (2φ)) (weighting function)
If the radius of the ring array antenna is r, the wavelength of the observation radio wave is λ, and the equivalent radius considering the elevation angle θ of the incoming wave is r ′ (r ′ = r sin θ), the evaluation function V (φ ′) = ∫W (φ Exp (−j2πr′cos φ / λ) · E (φ + φ ′) dφｄ can determine the direction and amplitude value of the incoming wave from −π / 2 to π / 2. That is, φ ′ is set and integration of −π / 2 to π / 2 is performed to obtain V (φ ′), and φ ′ is sequentially changed to obtain a peak V (φ ′) Φ ′ is the direction of arrival, and V ( φ ′ ) is the amplitude.
[0016]
In reception by the receiver Rr in steps (2) and (5), the main beam is directed to the stable direct wave arrival direction by the antenna directivity synthesis, and the beam null is directed to the unstable reflected wave arrival direction. As a result, temporal fluctuation (phase fluctuation due to multipath synthesis) of the phase comparison reference signal Sr (K, f) is suppressed. FIG. 3A shows the combined directivity of antenna elements A2, A5 and A8, and FIG. 3B shows the combined directivity of antenna elements A3, A4, A6 and A7. The direction of the main beam is the direct wave arrival direction (direction of the antenna element A5), and the null is the reflected wave arrival direction (direction of the antenna element A3).
[0017]
In the processing of steps (7) and (8), the phase difference between the phase comparison reference signals measured with the two antenna directivities is obtained, and one is calibrated to obtain the hologram observation result with the same phase reference. .
Interference and interference by observing hologram images of radio waves in a plurality of directions of arrival by repeating the steps (1) to (9) while rotating and scanning the antenna directivity direction for obtaining these phase comparison reference signals. Wave and multipath separation evaluation becomes possible. The relative level of the interference / interference wave is changed by the above scanning, but the relative level of the multipath is not changed. The antenna directivity scanning is performed by, for example, selecting the antenna elements A3, A6, A9, A4, A5, A7, A8 from the selection of the antenna elements A2, A5, A8 and the selection of A3, A4, A6, A7. Steps (1) to (9) are performed with the directivity direction switched from the antenna element A5 to the A6 direction as the selection state of (1), and the steps (1) to (9) are performed by sequentially shifting the antenna directivity direction in the same manner. Repeat.
[0018]
Next, a method for finding a stable direct wave arrival direction and an unstable reflected wave arrival direction will be described.
In the first method, all the antenna selector switches S1, S2 and S3 are set to the receiver Rr side, and the antenna element in the antenna selecting means which is close to the maximum reception level by a combination of arbitrary antenna element selection and whose level is stable in time. Find a selection combination. Normally, νr (n1 + n2 + n3) is sequentially selected so that An1 and An3 are adjacent antenna elements with respect to the antenna element An2.
[0019]
In the second method, in steps (1) to (9), an antenna element connected to the receiver Rr is appropriately selected to perform hologram observation, and a stable path having a large level is selected from the observation result. decide. This method requires trials of combinations of antenna elements connected to the receiver Rr and evaluation of time variation by multiple observations under the same conditions.
[0020]
In this way, the arrival direction of the direct wave and the arrival direction of the unstable reflected wave are known, and the antenna combined directivity characteristic is obtained in which the main beam is directed to the direct wave arrival direction and the null is directed to the unstable reflected wave arrival direction. Thus, stable hologram observation becomes possible by selecting antenna elements and performing steps (1) to (9) using the received signal of the selected combination of antenna elements as a phase reference.
[0021]
In the selection control / calculation / display unit 14 in FIG. 2, the antenna selection and the receiver selection are controlled in executing steps (1) to (9), and a stable direct wave and an unstable reflected wave are controlled. Antenna selection and receiver selection for determining the direction of arrival of the signal, the correction of step (8) and the calculation of step (9) are performed on the obtained data E (K, L), and the result of the calculation is expressed as φ ′ Display as a parameter.
[0022]
The array antenna may have any shape instead of the circumference. For example, as shown in FIG. 4, it may be a circumferential layered array antenna. In this case, steps (1) to (9) are performed on the array antennas of the respective layers to obtain data E (φ, Z) (where Z represents the number of layers), and this E (φ, Z) is obtained. Fourier transform is performed on Z, and V (φ ′, θ) = ∫W (φ) exp (−) with θ = π / 2−Ψ for the transformation result Γ (φ, Ψ) (Ψ is an elevation angle). j2πr sinθcos φ / λ) Γ (φ + φ ′, θ) dφ
∫ calculates -π / 2 to π / 2 to obtain a hologram reproduction image. In this way, one θ needs to be calculated for one φ ′, and the amount of calculation can be reduced.
[0023]
After selecting the antenna elements in the above was subjected to the receiver select whether to connect the selected antenna element to the throat of the receiver. However, the antenna element may be selected after first selecting the receiver to be connected. For example, as shown in FIG. 5, for each antenna element A1 to A24, the receiver selection switches S1 to S24 respectively select which of the receivers Rr and Rm is supplied with the received signal, and each of the switches S1 to S24 is selected. The switching contact r side on the receiver Rr side is connected to a Wilkinson power combiner SHr with an input selection switch, and the switching contact m side on each receiver Rm side of the switches S1 to S24 is connected to a Wilkinson power combiner SHm with an input selection switch. Connect to. The antenna element is selected so that the reference combined directivity pattern can be obtained by the power combiner SHr, and the received signal is supplied to the receiver Rr. The power combiner SHm sequentially selects each antenna element and supplies the received signal to the receiver Rm. The process after making the output of the receiver Rr a reference and interfering with the output of each antenna element sequentially received by the receiver Rm by the interferometer 11 is the same as in the previous embodiment.
[0024]
The embodiment shown in FIG. 2 has a feature that the number of switches used is smaller than that of this embodiment. In FIG. 2, Wilkinson power combiners SHr and SHm with input selection are omitted, and the contact points r side of the switches S1, S2, and S3 are connected to the input side of the receiver Rr, and the switches S1, S2, and S3 are connected. The contact m side may be connected to the input side of the receiver Rm. That is, group selection may be omitted. However, if the power combiners SHr and SHm are omitted, there is a possibility that the input signals at the receivers Rr and Rm will be reflected to the contact side where they are not connected and reflected to cause a harmful effect. By selecting only those connected using the devices SHr and SHm, the above-mentioned adverse effects can be eliminated.
[0025]
In FIG. 2, the number of grouped antenna elements is not limited to three. In FIGS. 2 and 5, the number of receivers is set to 3 or more, and interference between one reference receiver output and another receiver output is obtained, and the speed is increased by parallel processing. Also good.
[0026]
【The invention's effect】
According to the present invention, one or more of the antenna elements of the array antenna are used as the reference reception signal, and the other antenna elements are selectively connected by the switch, and the antenna is rotated equivalently to receive the reception signal of each antenna element. Since it interferes with the signal, it can be rotated at a higher speed than when the antenna is mechanically rotated, and hologram observation can be performed in a shorter time.
[0027]
Stable measurement is possible by simultaneously selecting a plurality of antenna elements and setting the direction of the main beam of the combined directional characteristics as the direct wave arrival direction.
Further, by making the composite directivity null the direction of the reflected wave or the interference wave, unstable reflected wave, interference / interference wave can be separated, and the influence of these can be eliminated.
[Brief description of the drawings]
FIG. 1A is a plan view showing an example of an array antenna used in the device of the present invention, and B is a sectional view taken along line AA.
FIG. 2 is a block diagram showing a functional configuration example of the inventive device.
FIG. 3 is a diagram showing an example of combined directivity characteristics by a plurality of antenna elements.
FIG. 4 is a diagram schematically showing another example of an array antenna.
FIG. 5 is a block diagram showing a functional configuration of another embodiment of the present invention.
FIG. 6 is a block diagram showing a conventional radio hologram observation apparatus.

Claims

An array antenna arranged in a circumferential layer ,
A plurality of antenna selecting means for dividing the received signal of each antenna element of the array antenna into a plurality of groups and selecting at least one for each group;
A plurality of receiver selection means for selectively supplying each received signal selected for each of the plurality of antenna selection means to any one of the switching terminals corresponding to the plurality of receivers;
A plurality of receivers each supplied with a reception signal from the corresponding switching terminal selected by the plurality of reception selection means;
Means for observing interference of a received signal by obtaining interference with the output of another receiver on the basis of one of the outputs of the plurality of receivers;
The interference observation value E (φ, Z) when the position in the direction parallel to the axis of the azimuth angle φ and the circumferential layer is Z is Fourier-transformed with respect to Z, and Γ (φ, Ψ) (Ψ is Means for obtaining an elevation angle)
As θ = π / 2-Ψ, V (φ ', θ) = ∫W (φ) exp (- j2 π r sin θ cos φ / λ) Γ (φ + φ', θ) dφ
∫ is −π / 2 to π / 2, λ is the wavelength of the received radio wave, W (φ) is the weighting function, φ ′ is the azimuth angle of interest,
And a means for obtaining a hologram reproduction image by calculating

Means for observing interference with each received signal of another group on the basis of at least one received signal of at least one group; and on the basis of at least one received signal in at least one of said other groups Means for observing interference with other received signals of other groups, means for observing interference between at least one of the two reference signals and obtaining a phase difference;
Means for correcting the interference observation result with each received signal so that each interference observation result becomes a common phase reference using the phase difference;
Means for performing a hologram reproduction process on the corrected interference observation result;
The radio hologram observation apparatus according to claim 1, further comprising:

3. The radio wave hologram observation apparatus according to claim 1, further comprising a plurality of group selection means for selecting a reception signal from a corresponding switching terminal of the receiver selection means and supplying the selected signal to the corresponding receiver.

An array antenna arranged in a circumferential layer ,
A plurality of receiver selection means for selectively supplying a received signal of each antenna element of the array antenna to one of switching terminals corresponding to the plurality of receivers;
A plurality of antenna selection means for receiving at least one received signal from each corresponding switching terminal of the plurality of receiver selection means, and selecting at least one of the received signals;
A plurality of receivers to which the outputs of the plurality of antenna selection means are respectively supplied;
Means for observing interference of a received signal by obtaining interference with the output of another receiver on the basis of one of the outputs of the plurality of receivers;
The interference observation value E (φ, Z) when the position in the direction parallel to the axis of the azimuth angle φ and the circumferential layer is Z is Fourier-transformed with respect to Z, and Γ (φ, Ψ) (Ψ is Means for obtaining an elevation angle)
As θ = π / 2-Ψ, V (φ ', θ) = ∫W (φ) exp (- j2 π r sin θ cos φ / λ) Γ (φ + φ', θ) dφ
∫ is −π / 2 to π / 2, λ is the wavelength of the received radio wave, W (φ) is the weighting function, φ ′ is the azimuth angle of interest,
And a means for obtaining a hologram reproduction image by calculating

5. The radio wave hologram observation apparatus according to claim 1, further comprising: means for observing the interference, the comparison reference being composed of a composite signal of a plurality of reception signals.

While receiving the same reception signal as a reference of the output of the receiver, any one of claims 1 to 5, characterized in that it comprises sequentially switching means receive antenna elements of the receiving signal inputted to the other receivers The radio hologram observation apparatus described in 1.