JP2004198312A

JP2004198312A - Radar equipment

Info

Publication number: JP2004198312A
Application number: JP2002368591A
Authority: JP
Inventors: Noriyuki Inaba; 敬之稲葉
Original assignee: Mitsubishi Electric Corp
Current assignee: Mitsubishi Electric Corp
Priority date: 2002-12-19
Filing date: 2002-12-19
Publication date: 2004-07-15
Anticipated expiration: 2022-12-19
Also published as: JP3833606B2

Abstract

<P>PROBLEM TO BE SOLVED: To provide radar equipment dealing with a narrow beam by enlarging the equivalent aperture even in the case that an array antenna with small number of elements is used. <P>SOLUTION: One of two element antennas positioned at the opposite ends of arrangement of the array antenna is made a transmission element antenna, the other is made a transmitting and receiving element antenna, a plurality of the residual element antennas are made receiving element antennas, and radar transmission waves are successively transmitted from the transmission antenna. Respective reflective waves are received in order of the receiving element antennas of corresponding order and the transmitting and receiving antenna. Next, the radar transmission waves are successively transmitted from the transmitting and receiving element antenna, and the respective reflective waves are received with the receiving element antennas of the corresponding order. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

【０００１】
【発明の属する技術分野】
この発明はアレーアンテナを使用してレーダ送信波を送信し、目標からの反射電波を受信するレーダ装置に関するのものである。
【０００２】
【従来の技術】
自動車に周波数変調レーダやパルス変調レーダ等のミリ波レーダを搭載して先行車両との車間距離や相対速度あるいは障害物を検出して自動車の安全性や自動運転などの利便性を図るシステムの開発が進められている。このような車載レーダは、多重波や他レーダ干渉波など、レーダの中でも比較的電波環境の悪い状況で運用されることになる。これらの対策の一つとして、アレーアンテナを用いた空間ダイバーシティや各種適応アレー信号処理の適用が効果的である。しかし、車載レーダは民生需要を目的とする一般車両に搭載するため、小型化、かつ簡素化による経済性が求められている。この種の従来の車載レーダとして、送信機、および受信機を１個のみ使用し、複数の受信素子アンテナとスイッチにより受信機との接続を切り替えるようにした構成がある（例えば、特許文献１）。
【０００３】
１次元アレーを例として、この従来のレーダ装置のアレーアンテナを１個の送信素子アンテナと９個の受信素子アンテナで構成した場合について考察する。送受信のタイミングチャートは図１１に示されるようになる。まず、送信素子アンテナＴ１から送信し、その目標反射波を受信素子アンテナＲ１で受信する。次に、同様に送信素子アンテナＴ１で送信し、その目標反射波は受信素子アンテナＲ２で受信する。以下同様に、送信素子アンテナＴ１で送信し、その目標反射波を受信素子アンテナＲ９で受信する。この送受信動作を、便宜上（Ｔ１，Ｒ１）、（Ｔ１，Ｒ２）、…、（Ｔ１，Ｒ９）と表すことにする。こうすることで、目標の方向をθとし、受信素子アンテナＲ１で受信した信号位相を基準として０とすると、位相が０，φ，２φ，３φ，４φ，５φ，６φ，７φ，８φだけ異なる信号が得られる。ここで、信号位相φは、
【数１】

となる。ここで、受信のアレーアンテナは、素子アンテナ間隔ｄのリニアアレーとした。このように、送信パルスの繰り返し時間間隔ＰＲＩ（ＰｕｌｓｅＲｅｐｅｔｉｔｉｏｎＩｎｔｅｒｖａｌ）をＴとすると、９Ｔの時間で９素子のアレーアンテナとしての受信信号が得られることになる。
【０００４】
このアンテナ装置では、ｎ個の受信素子アンテナを用いた場合、ｎＴの時間で、ｎ個のアレーアンテナ信号が得られることがわかる。図１２にはｎ＝９とした場合に得られたビーム形成例を示す。ここでは、±２０ｄｅｇを捜査範囲要求とみたてて、送信および受信素子アンテナ１個のパターン（ＴｘａｎｄＲｘｅｌｅｍｎｔＰａｔｔｅｒｎ）（破線）の幅は、それと同等の約４０ｄｅｇとした。図１２において２０ｄｅｇ方向へビーム指向させた場合の、９個の受信素子アンテナによる受信合成ビームパターン（ｂｅａｍｐａｔｔｅｒｎ（θｄ＝２０ｄｅｇ））を実線で示す。また、素子間隔ｄを１．３λ（λは波長）としており、グレーティングローブは捜索範囲外の−２５ｄｅｇ方向となっている。この時、１．３λ×１０の開口径が必要となり、ビーム幅は約４ｄｅｇが得られる。
【０００５】
【特許文献１】
特開２０００−２８４０４７公報
【０００６】
【発明が解決しようとする課題】
従来の車載用のレーダ装置は以上のように構成されているので、車に装備する場合の省スペース化には限界がある。すなわちアレーアンテナの素子数を低減した場合、その分開口が小さくなってしまい、また、遠方の並走する複数車両の分離を容易とするための狭ビーム化を損なうという問題があった。
また、サブアレー構成にした大規模アレーアンテナを用い、比較的遠方を捜索対象として全素子アンテナから送信する艦載用レーダや航空管制レーダなどがある。この大規模アレーアンテナでは、各素子アンテナは、個別に移相器を持ち、サブアレー合成ビームを形成するため送信位相あるいは受信位相を制御できるようにしている。しかし、多くの大規模アレーアンテナは、受信系数を低減し装置規模を削減するために、ＲＦ段で幾つかのサブアレーに合成する合成器を持つ構成が採用されている。このようなレーダにおいても運用状況によっては、電力的には十分であるが、より狭ビームが必要とされ、また、アレーアンテナの空間方向の自由度を要求されることが課題として考えられる。
【０００７】
この発明は上記のような課題を解決するためになされたもので、少ない素子数のアレーアンテナを用いて等価開口を大きくすることができ、一方、狭ビーム化にも対応可能なレーダ装置を得ることを目的とする。
【０００８】
【課題を解決するための手段】
この発明に係るレーダ装置は、複数の素子アンテナを所定の間隔で配列したアレーアンテナを用いて、レーダ送信波を一定間隔で順次に送信し、目標からの反射電波を受信し、受信した受信信号を合成して合成開口アレー信号として処理するレーダ装置において、アレーアンテナの配列の相対する端部に位置する２つの素子アンテナに送信および／もしくは送受信の機能を持たせ、２つの素子アンテナ間に位置する複数の素子アンテナを受信素子アンテナとし、送信素子アンテナおよび／もしくは送受信素子アンテナを用いて所定の送信信号に基づいてレーダ送信波を所定の順序で送信し、送受信素子アンテナの機能がある場合にはその送受信素子アンテナを含めた受信素子アンテナを用いてそれぞれの反射電波を対応させた順序で受信するよう送受信のサイクルを制御するようにしたものである。
【０００９】
【発明の実施の形態】
以下、この発明の各実施の形態について説明する。
実施の形態１．
図１はこの発明の実施の形態１によるレーダ装置の構成を示すブロック図である。図において、第１の送信機１はアレーアンテナ２から送出するレーダ送信波のための送信信号を一定間隔で生成し出力する。複数の素子アンテナを所定の間隔ｄで配列したアレーアンテナ２は、アレー配列の一端に位置し空間に電波を送出する送信素子アンテナＴ１、他端に位置し電波の送信と受信を行う送受信素子アンテナＴＲ２およびＴ１とＴＲ２の間に位置し目標から反射した電波を受信する４個の受信素子アンテナＲ１〜Ｒ４を形成している。送信スイッチ６は、送信素子アンテナＴ１と送受信素子アンテナＴＲ２へ供給する第１の送信機１の送信信号を振分ける切り替え動作を行う。サーキュレータ７は、送信信号を送受信素子アンテナＴＲ２へ与え、また、この送受信素子アンテナＴＲ２で受信した受信信号を、受信スイッチ３を介して受信機４へ与えるように設けられている。この受信スイッチ３は、受信素子アンテナＲ１〜Ｒ４と送受信素子アンテナＴＲ２で順次に受信した受信信号を受信機４へ入力する動作を行う。送信スイッチ６と受信スイッチ３は、アレーアンテナ２による送受信の組み合わせ動作を時分割で制御するよう互いに連動して動作する。受信機４は、受信信号を増幅、周波数変換して信号処理器５に出力し、信号処理器５は得られた信号から合成開口アレー信号を生成し、例えば、後段で車間距離、相対速度、障害物等のデータを算出させるために出力する。
【００１０】
次に、アレーアンテナ２を中心とした送受信の動作について説明する。図２は図１のアンテナ構成による送受信動作を示すタイミングチャートである。
まず、送信スイッチ６が、第１の送信機１からの送信信号を送信素子アンテナＴ１に供給するように切り替えられているとする。また、目標で反射して戻ってきた反射電波を受信素子アンテナＲ１が受信して、その受信信号を受信機４に与えられるよう受信スイッチ３を切り替えておくものとする。ここで、送信素子アンテナＴ１で送信し、受信素子アンテナＲ１で受信する場合の動作を、便宜上（Ｔ１，Ｒ１）のように表現することにし、他の素子アンテナについても同様とする。
【００１１】
まず、送信スイッチ６と受信スイッチ３の切り替えを制御し、送信素子アンテナＴ１からのレーダ送信波を順次に送信し、目標からのそれぞれの反射波を対応させた順序の受信素子アンテナＲ１，…，Ｒ４および送受信素子アンテナＴＲ２の順で受信する。次に、送受信素子アンテナＴＲ２からの送信に対して、それぞれの反射波を対応させた順序の受信素子アンテナＲ１，…，Ｒ４で順次に受信する。このようにして得た送受信動作は、（Ｔ１，Ｒ１）、（Ｔ１，Ｒ２）、（Ｔ１，Ｒ３）、（Ｔ１，Ｒ４）、（Ｔ１，ＴＲ２）、（ＴＲ２，Ｒ１）、（ＴＲ２，Ｒ２）、（ＴＲ２，Ｒ３）、（ＴＲ２，Ｒ４）の順になり、この送受信動作のサイクルを繰り返す。ここで、受信素子アンテナＲ１で受信した信号位相を基準にとると、位相が０，φ，２φ，３φ，４φ，５φ，６φ，７φ，８φだけ異なる信号が得られる。このことは、１個の送信素子アンテナと９素子の受信素子アンテナを持つ前述した従来のアンテナ装置が９Ｔ（Ｔは一組の送受信の時間とする）という計測時間内で得る受信信号と同じ信号を得ることができることを示している。すなわち、実施の形態１では、アレーアンテナの開口径が９素子に匹敵する。
【００１２】
一般に、従来のアンテナ構成では、等価開口ｎを実現するために、送信素子アンテナを含めてｎ＋１の素子数が必要となり、また実際の開口（以下、実開口とする。）はｎ×ｄとなる。一方、これに対し、この実施の形態１では、同じ等価開口ｎを実現するために、（ｎ＋１）／２の素子アンテナ数で、内訳として送受信素子アンテナ１＋送信素子アンテナ１＋受信素子アンテナ（ｎ＋１）／２−２とし、｛（ｎ＋１）／２＋１｝×ｄの実開口により、従来と同等の信号が得られることになる。
前述の従来の方法では、各送信の位相中心は送信素子アンテナＴ１で一定であった。しかし、素子の送信アンテナ機能をもう一つ増やして送受信を切り替えることで、送信の位相中心を含めた受信アレーに入力する信号の信号位相が決まることを利用して、実開口より大きな等価開口を得ることが可能となる。
【００１３】
また、この実施の形態１による方法で、送受信素子アンテナ１個、送信素子アンテナ１個、受信素子アンテナ８個として動作させた場合に得られた合成ビームパターンを図３に示す。図から分かるように、図１２に示した従来の受信素子アンテナと同等の実開口とした場合には、約２ｄｅｇ（従来の半分）のビーム幅が実現可能となる。ビーム内の多重波を分離するためには、ＭＵＳＩＣ（ＭＵｌｔｉｐｌｅＳＩｇｎａｌＣｌａｓｓｉｆｉｃａｔｉｏｎ）などの超分解能到来方向推定法などが知られているが、実施の形態１のビーム形成法は、この推定法に比べて素子間の振幅位相のキャリブレーション精度に対しても比較的寛容であるという良い特徴を持つ。
【００１４】
以上のように、この実施の形態１によれば、アレーアンテナ２の配列の相対する端部に位置する２つの素子アンテナの一方を送信素子アンテナＴ１とし、他方にサーキュレータ７を接続して送受信素子アンテナＴＲ２とすると共に、２つの素子アンテナＴ１、ＴＲ２間に位置する複数の素子アンテナを受信素子アンテナＲ１〜Ｒ４とし、送信素子アンテナＴ１からレーダ送信波を順次に送信して、それぞれの反射電波を対応させた順序の受信素子アンテナＲ１〜Ｒ４および送受信素子アンテナＴＲ２の順で受信し、次に、送受信素子アンテナＴＲ２からレーダ送信波を順次に送信して、それぞれの反射電波を対応させた順序の受信素子アンテナＲ１〜Ｒ４により受信するよう送受信のサイクルを制御するようにしているので、少ない受信素子アンテナ数のアレーアンテナ構成でその実開口の約２倍の等価開口を得ることができ、車載用レーダ装置として搭載されるアンテナの小型化に寄与する効果が得られる。また、この実施の形態１のアンテナ構成によれば、従来の構成と同じ実開口、すなわち同じ素子アンテナ数を持たせた場合には、ビーム幅を約半分に狭くできる効果が得られる。
【００１５】
実施の形態２．
この実施の形態２では、パルス変調レーダを想定しており、レーダ捜索対象とする目標の距離が比較的遠方であり、送信と受信を同一の素子アンテナで時分割制御できる状況を想定している。
図４はこの発明の実施の形態２によるレーダ装置の構成を示すブロック図である。図において、図１と異なる構成は、送信素子アンテナＴ１の代わりに送受信素子アンテナＴＲ１とサーキュレータ７’を設けた点である。すなわち、この実施の形態２は、アレーアンテナの配列の一端だけではなく、両端にサーキュレータ７’，７を接続した送受信素子アンテナＴＲ１、ＴＲ２を備える構成としたものである。
【００１６】
図５は実施の形態２に係る送受信動作を示すタイミングチャートである。図に示すように、この実施の形態２の場合、まず送受信素子アンテナＴＲ１で送信し、次の送信までの受信タイミング区間に、同じ送受信素子アンテナＴＲ１でも受信を行うようにしている。また、送受信のサイクルの最終段階では、送受信素子アンテナＴＲ２で送信して、自身でも受信を行うようにしている。送信スイッチ６と受信スイッチ３を時分割で制御することにより、送受信動作は、（ＴＲ１，ＴＲ１）、（ＴＲ１，Ｒ１）、（ＴＲ１，Ｒ２）、（ＴＲ１，Ｒ３）、（ＴＲ１，Ｒ４）、（ＴＲ１，ＴＲ２）、（ＴＲ２，Ｒ１），（ＴＲ２，Ｒ２）、（ＴＲ２，Ｒ３）、（ＴＲ２，Ｒ４）、（ＴＲ２，ＴＲ２）の順になり、この送受信動作のサイクルを繰り返す。送受信素子アンテナＴＲ１で受信した信号位相を基準にとると、位相が０，φ，２φ，３φ，４φ，５φ，６φ，７φ，８φ，９φ，１０φだけ異なる信号が得られる。したがって、全素子アンテナ数が実施の形態１と同数のとき、実施の形態１よりも２素子分だけ大きな開口が得られる。また、このときは計測時間１１Ｔが必要となる。
【００１７】
以上のように、この実施の形態２によれば、アレーアンテナ２の配列の相対する端部に位置する２つの素子アンテナにそれぞれサーキュレータを接続して送受信素子アンテナＴＲ１，ＴＲ２とすると共に、当該２つの素子アンテナＴＲ１，ＴＲ２間に位置する複数の素子アンテナを受信素子アンテナＲ１〜Ｒ４とし、一方の送受信素子アンテナＴＲ１からレーダ送信波を順次に送信して、それぞれの反射電波を当該一方の送受信素子アンテナＴＲ１、対応させた順序の受信素子アンテナＲ１〜Ｒ４および他方の送受信素子アンテナＴＲ２の順で受信し、次に、他方の送受信素子アンテナＴＲ２からレーダ送信波を順次に送信して、それぞれの反射電波を対応させた順序の受信素子アンテナＲ１〜Ｒ４および当該他方の送受信素子アンテナＴＲ２の順で受信するよう送受信のサイクルを制御するようにしているので、送受信素子アンテナＴＲ１，ＴＲ２による送受信を時分割制御することにより、少ない受信素子アンテナ数のアレーアンテナ構成で実開口の約２倍の等価開口を得ることができ、車載用レーダ装置として搭載されるアンテナとして小型化を実現する効果が得られる。また、受信素子アンテナ数を増やした場合には、狭ビーム化が図れる効果が得られる。なお、このようにして等価開口を大きくする方法を、以下、合成開口アレー構成と呼ぶこととする。
【００１８】
実施の形態３．
実施の形態１および実施の形態２では、アレーアンテナの素子数が比較的小さい場合を想定して説明してきたが、この実施の形態３では、大規模アレーアンテナをサブアレー構成にし、サブアレー間に実施の形態２で述べたような合成開口アレー構成を適用する場合について示す。
【００１９】
図６はこの発明の実施の形態３によるレーダ装置の構成を示すブロック図である。図において、図１と異なる部分について説明すると、アレーアンテナ２の配列の一端側の送受信素子アンテナＴＲ１１，ＴＲ１２，…，ＴＲ１ｍ（ただし、ｍは正の整数）で送受信用サブアレーＳＡ１を形成し、他端側の送受信素子アンテナＴＲ２１，ＴＲ２２，…，ＴＲ２ｍで送受信用サブアレーＳＡ４を形成する。また、受信素子アンテナＲ１１，Ｒ１２，…，Ｒ１ｍで受信用サブアレーＳＡ２を形成し、受信素子アンテナＲ２１，Ｒ２２，…，Ｒ２ｍで受信用サブアレーＳＡ３を形成している。各送受信素子アンテナおよび受信素子アンテナには移相器８が設けられている。受信信号を取り出す場合には各サブアレーに対してサブアレーを形成する素子アンテナの出力を合成する合成器９がそれぞれ設けられている。この例では、受信用サブアレーは２個であるが、その数は限定されるものではない。
【００２０】
送受信の動作の順序においては、送受信用サブアレーＳＡ１の送受信素子アンテナＴＲ１１，ＴＲ１２，…，ＴＲ１ｍで一斉に、かつ順次にレーダ送信波を送信し、反射波を送受信用サブアレーＳＡ１自身の送受信素子アンテナＴＲ１１，ＴＲ１２，…，ＴＲ１ｍで受信し、各受信信号を対応する合成器９で合成する。次に、反射波を対応させた順序の受信用サブアレーＳＡ２，ＳＡ３および送受信用サブアレーＳＡ４の順でそれぞれ受信して対応するそれぞれの合成器９で合成する。さらに、今度は送受信用サブアレーＳＡ４でレーダ送信波を順次に送信し、それぞれの反射波を受信用サブアレーＳＡ２，ＳＡ３および送受信用サブアレーＳＡ４自身の順で受信して対応するそれぞれの合成器９で合成し、送受信動作の１サイクルを形成する。したがって、送信スイッチ６と受信スイッチ３で制御されるサブアレーとしての送受信動作は、（ＳＡ１，ＳＡ１）、（ＳＡ１，ＳＡ２）、（ＳＡ１，ＳＡ３）、（ＳＡ１，ＳＡ４）、（ＳＡ４，ＳＡ１）、（ＳＡ４，ＳＡ２）、（ＳＡ４，ＳＡ３）、（ＳＡ４，ＳＡ４）の順になり、この送受信動作のサイクルを繰り返す。このように、大規模アレーアンテアンにおいても、サブアレーを構成要素として、実施の形態２と同様に、時分割送信により等価開口を大きくすることが可能となる。
【００２１】
以上のように、この実施の形態３によれば、アレーアンテナ２を、それぞれ移相器８を設けた所定数の素子アンテナからなる複数のサブアレーＳＡ１〜ＳＡ４で構成し、アレーアンテナ２の配列の相対する端部に位置する２つのサブアレーを、各素子アンテナにそれぞれサーキュレータを接続して送受信素子アンテナにした送受信用サブアレーＳＡ１，ＳＡ４とし、当該２つのサブアレーＳＡ１，ＳＡ４間に位置する複数のサブアレーを、各素子アンテナを受信素子アンテナとする受信用サブアレーＳＡ２，ＳＡ３とし、一方の送受信用サブアレーＳＡ１からレーダ送信波を順次に送信して、それぞれの反射電波を当該一方の送受信用サブアレーＳＡ１自身、対応させた順序の受信用サブアレーＳＡ２，ＳＡ３および他方の送受信用サブアレーＳＡ４の順で受信し、次に、他方の送受信用サブアレーＳＡ４からレーダ送信波を順次に送信して、それぞれの反射電波を対応させた受信用サブアレーＳＡ２，ＳＡ３および当該他方の送受信用サブアレーＳＡ４自身の順で受信するよう送受信のサイクルを制御し、サブアレー毎に素子アンテナで受信した受信信号を合成し、合成された各サブアレーの信号をさらに合成して合成開口アレー信号として処理するようにしているので、大規模アレーアンテアンに適用して少ない受信用サブアレー数のアレーアンテナ構成でその実開口に対して等価開口を十分大きくすることが可能となるため、空間方向の自由度に対する要求に対応できる効果がある。また、素子数を増やすことにより、狭ビーム化にも対応できる効果が得られる。
【００２２】
実施の形態４．
図７はこの発明の実施の形態４によるレーダ装置の構成を示すブロック図である。図において、図１と異なる部分について説明すると、第１の送信機１で発生する符合信号と直交する符号信号を発生する第２の送信機１０が設けられ、その出力が送信素子アンテナＴ１に供給されるようになっている。また、ここでは図１の送信スイッチ６を用いず第１の送信機１の出力がサーキュレータ７を介して送受信素子アンテナＴＲ２に与えられるように構成されている。加えて、受信機４で検波された直交する符号信号をそれぞれ復調する第１の復調器１１と第２復調器１２が設けられている。
【００２３】
図８は実施の形態４の送受信動作を示すタイミングチャートである。
まず、アレーアンテナ２の配列の両端にある送信素子アンテナＴ１と送受信素子アンテナＴＲ２から符号変調された直交信号によるレーダ送信波がそれぞれ同じタイミングで順次に送信され、反射波を受信素子アンテナＲ１，Ｒ２，Ｒ３，Ｒ４で受信する。次に、サーキュレータ７の切り替えタイミングにより、送信素子アンテナＴ１だけのレーダ送信波に対する反射波を送受信素子アンテナＴＲ２だけが受信する。したがって、送受信動作は、（Ｔ１＋ＴＲ２，Ｒ１），（Ｔ１＋ＴＲ２，Ｒ２），（Ｔ１＋ＴＲ２，Ｒ３），（Ｔ１＋ＴＲ２，Ｒ４），（Ｔ１，ＴＲ２）の順になり、この送受信動作のサイクルを繰り返す。
【００２４】
受信素子アンテナＲ１，Ｒ２，Ｒ３，Ｒ４で受信された信号は、受信機４で検波されて直交する符号信号となり、これら符号信号は第１の復調器１１と第２復調器１２によりそれぞれ復調される。復調された各信号は、送信素子アンテナＴ１および送受信素子アンテナＴＲ２から送信された信号の受信成分であり、それぞれの位相情報を含んでいる。その結果として、（０，５φ），（φ，６φ），（２φ，７φ），（３φ，８φ）の位相をもつ信号が得られる。最後に、（Ｔ１，ＴＲ２）の送受信動作で送受信素子アンテナＴＲ２により受信した信号は第１の復調器１１で復調され、４φの位相の信号として得られる。このように、合計５Ｔの時間内において、９素子アレーに相当する信号が得られるため、より高いデータレートが得られる制御方法となる。
【００２５】
以上のように、この実施の形態４によれば、アレーアンテナ２の配列の相対する端部に位置する２つの素子アンテナの一方を送信素子アンテナＴ１とし、他方にサーキュレータ７を接続して送受信素子アンテナＴＲ２とすると共に、２つの素子アンテナＴ１，ＴＲ２間に位置する複数の素子アンテナを受信素子アンテナＲ１〜Ｒ４とし、送信素子アンテナＴ１と送受信素子アンテナＴＲ２に対して互いに直交する送信信号を供給してレーダ送信波を同じタイミングで、かつ順次に送信し、それぞれの反射電波を対応させた順序の受信素子アンテナＲ１〜Ｒ４により受信し、次に、送信素子アンテナＴ１だけからレーダ送信波を送信し、その反射波を送受信素子アンテナＴＲ２で受信するよう送受信のサイクルを制御し、受信素子アンテナＲ１〜Ｒ４および送受信素子アンテナＴＲ２で受信された直交する受信信号をそれぞれ復調した後、復調した信号を合成して合成開口アレー信号として処理するようにしているので、少ない受信素子アンテナ数のアレーアンテナ構成で、その実開口に対し約２倍の等価開口を得ることができ、車載用レーダ装置として搭載されるアンテナの小型化に寄与する効果が得られる。また、受信素子アンテナ数を増やした場合には、狭ビーム化が図れる効果が得られる。
【００２６】
実施の形態５．
図９はこの発明の実施の形態５によるレーダ装置の構成を示すブロック図である。図において、図１と異なる部分は、送受信素子アンテナＴＲ２とサーキュレータ７を用いず、代わりに送信素子アンテナＴ２を設け、また受信素子アンテナＲ５を設けていることである。すなわち、この実施の形態５は、アレーアンテナ２の両端に送信専用の素子アンテナＴ１，Ｔ２を設ける構成を持つ。
【００２７】
図１０は実施の形態５に係る送受信動作を示すタイムチャートである。まず、送信素子アンテナＴ１からレーダ送信波を順次に送信し、それぞれの反射電波を対応させた順序の受信素子アンテナＲ１〜Ｒ５により順次に受信する。次に、送信素子アンテナＴ２からレーダ送信波を順次に送信し、それぞれの反射電波を対応させた順序の受信素子アンテナＲ１〜Ｒ５により順次に受信する。したがって、送信スイッチ６と受信スイッチ３の制御により送受信動作は、（Ｔ１，Ｒ１）、（Ｔ１，Ｒ２）、（Ｔ１，Ｒ３）、（Ｔ１，Ｒ４）、（Ｔ１，Ｒ５）、（Ｔ２，Ｒ１）、（Ｔ２，Ｒ２）、（Ｔ２，Ｒ３）、（Ｔ２，Ｒ４）、（Ｔ２，Ｒ５）の順になり、この送受信動作のサイクルを繰り返す。この実施の形態５の場合、実施の形態１と比較すると、素子数を１個増やすことで実開口が少し大きくなるが、サーキュレータを用いない分、装置の実装上有利な点が得られる。
【００２８】
以上のように、この実施の形態５によれば、アレーアンテナ２の配列の相対する端部に位置する２つの素子アンテナを送信素子アンテナＴ１，Ｔ２とすると共に、この２つの送信素子アンテナＴ１，Ｔ２間に位置する複数の素子アンテナを受信素子アンテナＲ１〜Ｒ５とし、一方の送信素子アンテナＴ１からレーダ送信波を順次に送信して、それぞれの反射電波を対応させた順序の受信素子アンテナＲ１〜Ｒ５により受信し、次に、他方の送信素子アンテナＴ２からレーダ送信波を順次に送信して、それぞれの反射電波を対応させた順序の受信素子アンテナＲ１〜Ｒ５により受信するよう送受信のサイクルを制御するようにしているので、実施の形態１よりは実開口が若干増えるが、少ない素子数のアレーアンテナ構成でその実開口に対し約２倍の等価開口を得ることができ、車載用レーダ装置として搭載されるアンテナの小型化に寄与する効果が得られる。また、受信素子アンテナ数を増やした場合には、狭ビーム化が図れる効果が得られる。
【００２９】
以上の各実施の形態においては１次元アレーについての例を説明してきたが、この発明は、２次元アレーに対しても、アレーアンテナの配列の相対する端部に送信機能を有する素子を配置することにより拡張可能であり、上記各実施の形態で述べたように、同様な効果が得られる。
【００３０】
【発明の効果】
以上のように、この発明によれば、アレーアンテナの配列の相対する端部の素子アンテナに送信機能をもたせ、時分割あるいは同期した直交符号信号を送信することで、送受信を含めたレーダ信号の位相差から時分割あるいは符号分割による合成開口アンテナ構成を実現し、実開口に対し大きな等価開口を得ることができ、アレーアンテナの構成の大幅な小型化が図れる効果がある。また、実開口を増やした場合には、より狭ビーム化が図れる効果がある。
【図面の簡単な説明】
【図１】この発明の実施の形態１によるレーダ装置の構成を示すブロック図である。
【図２】この発明の実施の形態１に係る送受信動作を示すタイミングチャートである。
【図３】この発明の実施の形態１に係る合成ビームパターンを示す説明図である。
【図４】この発明の実施の形態２によるレーダ装置の構成を示すブロック図である。
【図５】この発明の実施の形態２に係る送受信動作を示すタイミングチャートである。
【図６】この発明の実施の形態３によるレーダ装置の構成を示すブロック図である。
【図７】この発明の実施の形態４によるレーダ装置の構成を示すブロック図である。
【図８】この発明の実施の形態４に係る送受信動作を示すタイミングチャートである。
【図９】この発明の実施の形態５によるレーダ装置の構成を示すブロック図である。
【図１０】この発明の実施の形態５に係る送受信動作を示すタイミングチャートである。
【図１１】従来のアンテナ装置の送受信動作を説明するタイミングチャートである。
【図１２】従来のアンテナ装置に係る合成ビームパターンを示す説明図である。
【符号の説明】
１第１の送信機、２アレーアンテナ、３受信スイッチ、４受信機、５信号処理器、６送信スイッチ、７サーキュレータ、８移相器、９合成器、１０第２の送信機、１１第１の復調器、１２第２の復調器、Ｒ１〜Ｒ５，Ｒ１１〜Ｒ１ｍ，Ｒ２１〜Ｒ２ｍ受信素子アンテナ、ＳＡ１，ＳＡ４送受信用サブアレー、ＳＡ２，ＳＡ３受信用サブアレー、Ｔ１，Ｔ２送信素子アンテナ、ＴＲ１，ＴＲ２，ＴＲ１１〜ＴＲ１ｍ，ＴＲ２１〜ＴＲ２ｍ送受信素子アンテナ。[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a radar device that transmits a radar transmission wave using an array antenna and receives a reflected radio wave from a target.
[0002]
[Prior art]
Development of a system that mounts millimeter-wave radar such as frequency-modulated radar and pulse-modulated radar on an automobile and detects the distance between vehicles, the relative speed with respect to the preceding vehicle, and obstacles to improve vehicle safety and convenience such as automatic driving Is being promoted. Such an in-vehicle radar is operated in a relatively poor radio wave environment among radars, such as a multiplex wave and another radar interference wave. As one of these countermeasures, it is effective to apply spatial diversity using an array antenna and various kinds of adaptive array signal processing. However, since the on-vehicle radar is mounted on a general vehicle for consumer demand, economical efficiency due to miniaturization and simplification is required. As this type of conventional on-vehicle radar, there is a configuration in which only one transmitter and one receiver are used, and the connection with the receiver is switched by a plurality of receiving element antennas and switches (for example, Patent Document 1). .
[0003]
Taking a one-dimensional array as an example, consider a case where the array antenna of this conventional radar device is configured with one transmitting element antenna and nine receiving element antennas. The timing chart of the transmission and reception is as shown in FIG. First, transmission is performed from the transmitting element antenna T1, and the target reflected wave is received by the receiving element antenna R1. Next, transmission is similarly performed by the transmitting element antenna T1, and the target reflected wave is received by the receiving element antenna R2. Similarly, transmission is performed by the transmitting element antenna T1, and the target reflected wave is received by the receiving element antenna R9. This transmission / reception operation is represented as (T1, R1), (T1, R2),..., (T1, R9) for convenience. In this way, if the target direction is set to θ and the signal phase received by the receiving element antenna R1 is set to 0 as a reference, signals having phases different by 0, φ, 2φ, 3φ, 4φ, 5φ, 6φ, 7φ, and 8φ Is obtained. Here, the signal phase φ is
(Equation 1)

It becomes. Here, the receiving array antenna was a linear array with an element antenna spacing d. As described above, if the repetition time interval PRI (Pulse Repetition Interval) of the transmission pulse is T, a received signal as an array antenna of nine elements can be obtained in a time of 9T.
[0004]
In this antenna device, it can be seen that when n receiving element antennas are used, n array antenna signals can be obtained in nT time. FIG. 12 shows an example of beam formation obtained when n = 9. Here, ± 20 deg is regarded as a search range request, and the width of the pattern (Tx and Rx element Pattern) of one transmitting and receiving element antenna (broken line) is set to approximately 40 deg, which is equivalent to the pattern. In FIG. 12, a solid beam represents a received combined beam pattern (beam pattern (θd = 20 deg)) of the nine receiving element antennas when the beam is directed in the direction of 20 deg. The element interval d is 1.3λ (λ is the wavelength), and the grating lobe is in the −25 deg direction outside the search range. At this time, an aperture diameter of 1.3λ × 10 is required, and a beam width of about 4 deg is obtained.
[0005]
[Patent Document 1]
JP 2000-284047 A
[0006]
[Problems to be solved by the invention]
Since the conventional on-vehicle radar device is configured as described above, there is a limit in saving space when the radar device is mounted on a vehicle. That is, when the number of elements of the array antenna is reduced, there is a problem in that the aperture becomes smaller by that amount, and the beam narrowing for facilitating separation of a plurality of vehicles running in parallel at a distance is impaired.
In addition, there are shipboard radars and air traffic control radars which use a large-scale array antenna having a sub-array configuration and transmit signals from all the element antennas for a relatively distant search target. In this large-scale array antenna, each element antenna has an individual phase shifter so that a transmission phase or a reception phase can be controlled to form a sub-array composite beam. However, many large-scale array antennas adopt a configuration having a combiner that combines several sub-arrays at the RF stage in order to reduce the number of receiving systems and reduce the size of the device. In such a radar, depending on the operation conditions, the power is sufficient, but a narrower beam is required, and the degree of freedom in the spatial direction of the array antenna is required.
[0007]
SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and provides a radar apparatus which can increase the equivalent aperture by using an array antenna having a small number of elements, and can cope with a narrow beam. The purpose is to:
[0008]
[Means for Solving the Problems]
A radar apparatus according to the present invention uses an array antenna in which a plurality of element antennas are arranged at predetermined intervals, sequentially transmits radar transmission waves at regular intervals, receives reflected radio waves from a target, and receives a received signal. Device that combines the two antennas and processes them as a synthetic aperture array signal, the two element antennas located at the opposite ends of the array of array antennas have transmission and / or transmission / reception functions. A plurality of element antennas to be used as reception element antennas, transmit radar transmission waves in a predetermined order based on predetermined transmission signals using transmission element antennas and / or transmission / reception element antennas, and have a function of transmission / reception element antennas. Receives the reflected radio waves in the corresponding order using the receiving element antennas including the transmitting and receiving element antennas Cormorant is obtained so as to control the transmission and reception cycle.
[0009]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described.
Embodiment 1 FIG.
FIG. 1 is a block diagram showing a configuration of a radar apparatus according to Embodiment 1 of the present invention. In the figure, a first transmitter 1 generates and outputs a transmission signal for a radar transmission wave transmitted from an array antenna 2 at regular intervals. An array antenna 2 in which a plurality of element antennas are arranged at a predetermined interval d is a transmitting element antenna T1 located at one end of the array and transmitting a radio wave to a space, and a transmitting / receiving element antenna located at the other end and transmitting and receiving a radio wave. Four receiving element antennas R1 to R4, which are located between TR2 and T1 and TR2 and receive radio waves reflected from the target, are formed. The transmission switch 6 performs a switching operation of distributing the transmission signal of the first transmitter 1 supplied to the transmission element antenna T1 and the transmission / reception element antenna TR2. The circulator 7 is provided so as to supply a transmission signal to the transmission / reception element antenna TR2 and to supply a reception signal received by the transmission / reception element antenna TR2 to the receiver 4 via the reception switch 3. The reception switch 3 performs an operation of inputting, to the receiver 4, reception signals sequentially received by the reception element antennas R1 to R4 and the transmission / reception element antenna TR2. The transmission switch 6 and the reception switch 3 operate in conjunction with each other to control the combined operation of transmission and reception by the array antenna 2 in a time-division manner. The receiver 4 amplifies and frequency-converts the received signal and outputs it to the signal processor 5, which generates a synthetic aperture array signal from the obtained signal. For example, the inter-vehicle distance, relative speed, Output to calculate data of obstacles and the like.
[0010]
Next, transmission and reception operations centered on the array antenna 2 will be described. FIG. 2 is a timing chart showing a transmission / reception operation using the antenna configuration of FIG.
First, it is assumed that the transmission switch 6 has been switched to supply a transmission signal from the first transmitter 1 to the transmission element antenna T1. It is also assumed that the receiving element antenna R1 receives the reflected radio wave reflected back from the target and the receiving switch 3 is switched so that the received signal can be given to the receiver 4. Here, the operation when transmitting by the transmitting element antenna T1 and receiving by the receiving element antenna R1 is expressed as (T1, R1) for convenience, and the same applies to other element antennas.
[0011]
First, switching between the transmission switch 6 and the reception switch 3 is controlled, radar transmission waves from the transmission element antenna T1 are sequentially transmitted, and the reception element antennas R1,. R4 and the transmitting / receiving element antenna TR2 are received in this order. Next, with respect to the transmission from the transmitting / receiving element antenna TR2, the reflected waves are sequentially received by the receiving element antennas R1,. The transmission / reception operations thus obtained include (T1, R1), (T1, R2), (T1, R3), (T1, R4), (T1, TR2), (TR2, R1), (TR2, R2). ), (TR2, R3), (TR2, R4), and the cycle of the transmission / reception operation is repeated. Here, based on the signal phase received by the receiving element antenna R1, signals having phases different by 0, φ, 2φ, 3φ, 4φ, 5φ, 6φ, 7φ, and 8φ are obtained. This is the same signal as the received signal obtained by the above-described conventional antenna apparatus having one transmitting element antenna and nine receiving element antennas within a measurement time of 9T (T is a set of transmission and reception times). It is shown that can be obtained. That is, in the first embodiment, the aperture diameter of the array antenna is equivalent to nine elements.
[0012]
Generally, in the conventional antenna configuration, in order to realize the equivalent aperture n, n + 1 elements including the transmitting element antenna are required, and the actual aperture (hereinafter, referred to as the actual aperture) is n × d. . On the other hand, in the first embodiment, in order to realize the same equivalent aperture n, the number of element antennas is (n + 1) / 2, and the transmission / reception element antenna 1 + transmission element antenna 1 + reception element antenna (n + 1) / 2-2, and an actual aperture of {(n + 1) / 2 + 1} × d provides a signal equivalent to the conventional one.
In the above-described conventional method, the phase center of each transmission is constant at the transmitting element antenna T1. However, by increasing the transmission antenna function of the element and switching between transmission and reception, the signal phase of the signal input to the reception array including the phase center of the transmission is determined. It is possible to obtain.
[0013]
FIG. 3 shows a combined beam pattern obtained when the method according to the first embodiment is operated as one transmitting / receiving element antenna, one transmitting element antenna, and eight receiving element antennas. As can be seen from the drawing, a beam width of about 2 deg (half the conventional width) can be realized when the actual aperture is the same as that of the conventional receiving element antenna shown in FIG. In order to separate the multiple waves in the beam, a super-resolution direction-of-arrival estimation method such as MUSIC (Multiple Signal Classification) is known. However, the beam forming method according to the first embodiment is compared with this estimation method. It has a good feature that it is relatively tolerant to the calibration accuracy of the amplitude and phase between elements.
[0014]
As described above, according to the first embodiment, one of the two element antennas located at the opposite ends of the array of the array antenna 2 is used as the transmitting element antenna T1, and the circulator 7 is connected to the other, so that the transmitting and receiving elements are connected. In addition to the antenna TR2, a plurality of element antennas located between the two element antennas T1 and TR2 are referred to as reception element antennas R1 to R4, and radar transmission waves are sequentially transmitted from the transmission element antenna T1 and reflected radio waves are transmitted. Receiving element antennas R1 to R4 and transmitting and receiving element antenna TR2 are received in this order, and then radar transmission waves are sequentially transmitted from transmitting and receiving element antenna TR2, and the reflected radio waves are made to correspond to each other. Since the transmission / reception cycle is controlled so as to be received by the reception element antennas R1 to R4, the number of reception elements is small. It can be obtained about twice the equivalent aperture of the real aperture array antenna configuration number of antenna, effect contributing to the miniaturization of the antenna to be mounted as a vehicle-mounted radar apparatus is obtained. Further, according to the antenna configuration of the first embodiment, when the same actual aperture as the conventional configuration, that is, the same number of element antennas is provided, an effect that the beam width can be reduced to about half is obtained.
[0015]
Embodiment 2 FIG.
In the second embodiment, a pulse-modulated radar is assumed, a target of a radar search target is relatively long, and a situation in which transmission and reception can be time-divisionally controlled by the same element antenna is assumed. .
FIG. 4 is a block diagram showing a configuration of a radar device according to Embodiment 2 of the present invention. In the figure, the configuration different from FIG. 1 is that a transmitting / receiving element antenna TR1 and a circulator 7 ′ are provided instead of the transmitting element antenna T1. That is, in the second embodiment, not only one end of the array antenna array but also the transmitting and receiving element antennas TR1 and TR2 having circulators 7 'and 7 connected to both ends are provided.
[0016]
FIG. 5 is a timing chart showing a transmission / reception operation according to the second embodiment. As shown in the figure, in the case of the second embodiment, transmission is first performed by the transmission / reception element antenna TR1, and reception is performed by the same transmission / reception element antenna TR1 in a reception timing section until the next transmission. In the last stage of the transmission / reception cycle, transmission / reception is performed by the transmission / reception element antenna TR2 and reception is performed by itself. By controlling the transmission switch 6 and the reception switch 3 in a time-division manner, the transmission / reception operation is (TR1, TR1), (TR1, R1), (TR1, R2), (TR1, R3), (TR1, R4), (TR1, TR2), (TR2, R1), (TR2, R2), (TR2, R3), (TR2, R4), (TR2, TR2), and the cycle of the transmission / reception operation is repeated. With reference to the signal phase received by the transmitting / receiving element antenna TR1, signals having phases different by 0, φ, 2φ, 3φ, 4φ, 5φ, 6φ, 7φ, 8φ, 9φ, and 10φ are obtained. Therefore, when the number of all element antennas is the same as that in the first embodiment, an opening larger by two elements than in the first embodiment can be obtained. In this case, a measurement time of 11T is required.
[0017]
As described above, according to the second embodiment, the circulator is connected to each of the two element antennas located at the opposite ends of the array of the array antenna 2 to form the transmission / reception element antennas TR1 and TR2. A plurality of element antennas located between the two element antennas TR1 and TR2 are called reception element antennas R1 to R4, and radar transmission waves are sequentially transmitted from one transmission / reception element antenna TR1, and each reflected radio wave is transmitted to the one transmission / reception element. The antenna TR1, the receiving element antennas R1 to R4 in the corresponding order, and the other transmitting / receiving element antenna TR2 are received in this order, and then the radar transmitting wave is sequentially transmitted from the other transmitting / receiving element antenna TR2, and the respective reflected waves are reflected. Receiving element antennas R1 to R4 and the other transmitting / receiving element antenna TR in the order corresponding to radio waves The transmission / reception cycle is controlled so as to receive in the order described above, so that transmission / reception by the transmission / reception element antennas TR1 and TR2 is time-divisionally controlled, so that an array antenna configuration with a small number of reception element antennas is about twice as large as the actual aperture. And an effect of realizing miniaturization as an antenna mounted as an on-vehicle radar device can be obtained. Further, when the number of receiving element antennas is increased, an effect of narrowing the beam can be obtained. The method of increasing the equivalent aperture in this manner is hereinafter referred to as a synthetic aperture array configuration.
[0018]
Embodiment 3 FIG.
Although the first and second embodiments have been described on the assumption that the number of elements of the array antenna is relatively small, in the third embodiment, a large-scale array antenna is formed in a sub-array configuration, and is implemented between sub-arrays. A case where the synthetic aperture array configuration as described in the second embodiment is applied will be described.
[0019]
FIG. 6 is a block diagram showing a configuration of a radar device according to Embodiment 3 of the present invention. In the drawing, the parts different from those in FIG. 1 will be described. A transmitting / receiving sub-array SA1 is formed by transmitting / receiving element antennas TR11, TR12,..., TR1m (where m is a positive integer) on one end side of the array antenna 2 array. A transmitting / receiving sub-array SA4 is formed by the transmitting / receiving element antennas TR21, TR22,..., TR2m on the end side. Also, the receiving element antennas R11, R12, ..., R1m form a receiving sub-array SA2, and the receiving element antennas R21, R22, ..., R2m form a receiving sub-array SA3. A phase shifter 8 is provided for each transmitting / receiving element antenna and receiving element antenna. To extract a received signal, a combiner 9 is provided for each sub-array to combine the outputs of the element antennas forming the sub-array. In this example, the number of receiving sub-arrays is two, but the number is not limited.
[0020]
In the order of the transmitting and receiving operations, the transmitting and receiving element antennas TR11, TR12,..., TR1m of the transmitting and receiving sub-array SA1 transmit the radar transmission waves simultaneously and sequentially, and reflect the reflected waves. , TR12,..., TR1m, and the received signals are combined by the corresponding combiner 9. Next, the reflected waves are received in the order of the receiving sub-arrays SA2 and SA3 and the transmitting / receiving sub-array SA4 in the corresponding order, and are combined by the corresponding combiners 9. Further, this time, the radar transmission wave is sequentially transmitted by the transmission / reception sub-array SA4, and the respective reflected waves are received in the order of the reception sub-arrays SA2, SA3 and the transmission / reception sub-array SA4, and are combined by the corresponding combiners 9 respectively. Then, one cycle of the transmission / reception operation is formed. Therefore, the transmission / reception operation as a sub-array controlled by the transmission switch 6 and the reception switch 3 includes (SA1, SA1), (SA1, SA2), (SA1, SA3), (SA1, SA4), (SA4, SA1), (SA4, SA2), (SA4, SA3), (SA4, SA4), and the cycle of the transmission / reception operation is repeated. As described above, even in a large-scale array antenna, it is possible to increase the equivalent aperture by time division transmission using the sub-array as a component, as in the second embodiment.
[0021]
As described above, according to the third embodiment, the array antenna 2 is configured by the plurality of sub-arrays SA1 to SA4 each including a predetermined number of element antennas each provided with the phase shifter 8, and the arrangement of the array antenna 2 is The two sub-arrays located at the opposite ends are respectively defined as transmission / reception sub-arrays SA1 and SA4, each of which is a transmission / reception element antenna by connecting a circulator to each element antenna, and a plurality of sub-arrays located between the two sub-arrays SA1 and SA4. The receiving sub-arrays SA2 and SA3, each of which uses the element antenna as a receiving element antenna, sequentially transmit radar transmission waves from one transmitting / receiving sub-array SA1 and transmit each reflected radio wave to the one transmitting / receiving sub-array SA1 itself. The receiving sub-arrays SA2 and SA3 and the other transmitting / receiving sub-array The receiving sub-arrays SA2 and SA3 corresponding to the respective reflected radio waves and the other receiving / receiving sub-arrays SA4 themselves transmit the radar transmission waves sequentially from the other transmitting / receiving sub-array SA4. The received signal received by the element antenna is combined for each sub-array, and the combined signals of the respective sub-arrays are further combined and processed as a combined aperture array signal. Therefore, by applying to a large-scale array antenna, it is possible to sufficiently increase the equivalent aperture with respect to the actual aperture with an array antenna configuration having a small number of receiving sub-arrays. There is. Further, by increasing the number of elements, an effect that can cope with narrowing of the beam can be obtained.
[0022]
Embodiment 4 FIG.
FIG. 7 is a block diagram showing a configuration of a radar apparatus according to Embodiment 4 of the present invention. In the figure, a portion different from FIG. 1 will be described. A second transmitter 10 that generates a code signal orthogonal to a code signal generated by the first transmitter 1 is provided, and the output is supplied to a transmission element antenna T1. It is supposed to be. In addition, here, the configuration is such that the output of the first transmitter 1 is provided to the transmission / reception element antenna TR2 via the circulator 7 without using the transmission switch 6 of FIG. In addition, a first demodulator 11 and a second demodulator 12 for respectively demodulating orthogonal code signals detected by the receiver 4 are provided.
[0023]
FIG. 8 is a timing chart showing the transmission / reception operation of the fourth embodiment.
First, radar transmission waves based on code-modulated quadrature signals are sequentially transmitted from the transmission element antenna T1 and the transmission / reception element antenna TR2 at both ends of the array of the array antenna 2 at the same timing, and the reflected waves are transmitted to the reception element antennas R1 and R2. , R3, R4. Next, according to the switching timing of the circulator 7, only the transmitting / receiving element antenna TR2 receives a reflected wave with respect to the radar transmission wave of only the transmitting element antenna T1. Therefore, the transmission / reception operation is in the order of (T1 + TR2, R1), (T1 + TR2, R2), (T1 + TR2, R3), (T1 + TR2, R4), (T1, TR2), and the cycle of the transmission / reception operation is repeated.
[0024]
The signals received by the receiving element antennas R1, R2, R3, and R4 are detected by the receiver 4 to become orthogonal code signals, and these code signals are demodulated by the first demodulator 11 and the second demodulator 12, respectively. You. Each demodulated signal is a received component of a signal transmitted from the transmitting element antenna T1 and the transmitting / receiving element antenna TR2, and includes respective phase information. As a result, signals having phases of (0, 5φ), (φ, 6φ), (2φ, 7φ), and (3φ, 8φ) are obtained. Finally, the signal received by the transmission / reception element antenna TR2 in the transmission / reception operation of (T1, TR2) is demodulated by the first demodulator 11, and is obtained as a signal having a phase of 4φ. As described above, since a signal corresponding to a nine-element array is obtained within a total time of 5T, the control method can obtain a higher data rate.
[0025]
As described above, according to the fourth embodiment, one of the two element antennas located at the opposite ends of the array of the array antenna 2 is set as the transmitting element antenna T1, and the circulator 7 is connected to the other, so that the transmitting and receiving elements are connected. A plurality of element antennas located between the two element antennas T1 and TR2 are set as reception element antennas R1 to R4, and transmission signals orthogonal to each other are supplied to the transmission element antenna T1 and the transmission / reception element antenna TR2. And transmits the radar transmission waves at the same timing and sequentially, receives the respective reflected radio waves by the receiving element antennas R1 to R4 in the corresponding order, and then transmits the radar transmission wave only from the transmission element antenna T1. , The transmission / reception cycle is controlled so that the reflected wave is received by the transmission / reception element antenna TR2. After demodulating the orthogonal reception signals received by the R4 and the transmission / reception element antenna TR2, the demodulated signals are combined and processed as a synthetic aperture array signal, so that the array antenna configuration has a small number of reception element antennas. Thus, an equivalent aperture approximately twice as large as the actual aperture can be obtained, and the effect of contributing to miniaturization of the antenna mounted as the on-vehicle radar device can be obtained. Further, when the number of receiving element antennas is increased, an effect of narrowing the beam can be obtained.
[0026]
Embodiment 5 FIG.
FIG. 9 is a block diagram showing a configuration of a radar apparatus according to Embodiment 5 of the present invention. In the figure, the difference from FIG. 1 is that a transmitting / receiving element antenna T2 and a receiving element antenna R5 are provided instead of using the transmitting / receiving element antenna TR2 and the circulator 7. That is, the fifth embodiment has a configuration in which element antennas T1 and T2 dedicated to transmission are provided at both ends of the array antenna 2.
[0027]
FIG. 10 is a time chart showing the transmission / reception operation according to the fifth embodiment. First, radar transmission waves are sequentially transmitted from the transmission element antenna T1, and the respective reflected radio waves are sequentially received by the reception element antennas R1 to R5 in the corresponding order. Next, radar transmission waves are sequentially transmitted from the transmission element antenna T2, and the reflected radio waves are sequentially received by the reception element antennas R1 to R5 in the corresponding order. Therefore, the transmission and reception operation is controlled by the control of the transmission switch 6 and the reception switch 3 as (T1, R1), (T1, R2), (T1, R3), (T1, R4), (T1, R5), (T2, R1). ), (T2, R2), (T2, R3), (T2, R4), (T2, R5), and the cycle of this transmission / reception operation is repeated. In the case of the fifth embodiment, as compared with the first embodiment, although the actual aperture is slightly increased by increasing the number of elements by one, an advantage in mounting the device is obtained because the circulator is not used.
[0028]
As described above, according to the fifth embodiment, the two element antennas located at the opposite ends of the array of the array antenna 2 are the transmission element antennas T1 and T2, and the two transmission element antennas T1 and T2. The plurality of element antennas located between T2 are reception element antennas R1 to R5, and radar transmission waves are sequentially transmitted from one transmission element antenna T1, and the reception element antennas R1 to R1 in the order corresponding to the respective reflected radio waves. R5, then the radar transmission wave is sequentially transmitted from the other transmission element antenna T2, and the transmission / reception cycle is controlled so that each reflected radio wave is received by the reception element antennas R1 to R5 in the corresponding order. Therefore, although the actual aperture is slightly increased as compared with the first embodiment, the actual aperture is reduced with respect to the actual aperture by an array antenna configuration having a small number of elements. It can be obtained twice the equivalent aperture, effect contributing to the miniaturization of the antenna to be mounted as a vehicle-mounted radar apparatus is obtained. Further, when the number of receiving element antennas is increased, an effect of narrowing the beam can be obtained.
[0029]
In each of the above embodiments, an example of a one-dimensional array has been described. However, in the present invention, an element having a transmission function is arranged at an opposite end of an array of an array antenna also in a two-dimensional array. As a result, similar effects can be obtained as described in the above embodiments.
[0030]
【The invention's effect】
As described above, according to the present invention, the element antennas at the opposite ends of the array of array antennas are provided with a transmission function, and time-division or synchronized orthogonal code signals are transmitted, whereby radar signals including transmission and reception are transmitted. By realizing a synthetic aperture antenna configuration by time division or code division from the phase difference, it is possible to obtain a large equivalent aperture with respect to the actual aperture, and there is an effect that the configuration of the array antenna can be significantly reduced in size. When the actual aperture is increased, there is an effect that the beam can be narrowed.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a configuration of a radar device according to Embodiment 1 of the present invention.
FIG. 2 is a timing chart showing a transmission / reception operation according to Embodiment 1 of the present invention.
FIG. 3 is an explanatory diagram showing a combined beam pattern according to the first embodiment of the present invention.
FIG. 4 is a block diagram showing a configuration of a radar device according to Embodiment 2 of the present invention.
FIG. 5 is a timing chart showing a transmission / reception operation according to Embodiment 2 of the present invention.
FIG. 6 is a block diagram showing a configuration of a radar device according to Embodiment 3 of the present invention.
FIG. 7 is a block diagram showing a configuration of a radar apparatus according to Embodiment 4 of the present invention.
FIG. 8 is a timing chart showing a transmission / reception operation according to Embodiment 4 of the present invention.
FIG. 9 is a block diagram showing a configuration of a radar device according to Embodiment 5 of the present invention.
FIG. 10 is a timing chart showing a transmission / reception operation according to Embodiment 5 of the present invention.
FIG. 11 is a timing chart illustrating a transmission / reception operation of a conventional antenna device.
FIG. 12 is an explanatory diagram showing a combined beam pattern according to a conventional antenna device.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 1st transmitter, 2 array antennas, 3 reception switches, 4 receivers, 5 signal processors, 6 transmission switches, 7 circulators, 8 phase shifters, 9 synthesizers, 10 second transmitters, 11 first , 12 second demodulator, R1 to R5, R11 to R1m, R21 to R2m receiving element antenna, SA1, SA4 transmitting / receiving subarray, SA2, SA3 receiving subarray, T1, T2 transmitting element antenna, TR1, TR2 , TR11-TR1m, TR21-TR2m Transmitting and receiving element antennas.

Claims

Using an array antenna in which a plurality of element antennas are arranged at predetermined intervals, radar transmission waves are sequentially transmitted at regular intervals, reflected radio waves from a target are received, and the received signals are combined to synthesize a synthetic aperture array signal. In a radar device that processes as
Two element antennas located at opposite ends of the array of the array antennas have transmission and / or transmission / reception functions, and a plurality of element antennas located between the two element antennas are reception element antennas,
A transmitting element antenna and / or a transmitting / receiving element antenna for transmitting radar transmission waves in a predetermined order based on a predetermined transmitting signal, and a receiving element including the transmitting / receiving element antenna if the transmitting / receiving element antenna has a function; A radar apparatus wherein a transmission / reception cycle is controlled so that each reflected radio wave is received in a corresponding order using an antenna.

One of two element antennas located at opposite ends of the array of array antennas is a transmitting element antenna, and the other is connected to a circulator to form a transmitting and receiving element antenna, and a plurality of elements located between the two element antennas The antenna is a receiving element antenna,
A radar transmission wave is sequentially transmitted from the transmission element antenna, and the respective reflected radio waves are received in the order of the corresponding reception element antenna and the transmission / reception element antenna, and then the radar transmission wave is transmitted from the transmission / reception element antenna. 2. The radar apparatus according to claim 1, wherein the transmitting and receiving are sequentially transmitted, and a cycle of transmission and reception is controlled such that each reflected radio wave is received by the receiving element antennas in the corresponding order.

A circulator is connected to each of the two element antennas located at opposite ends of the array of the array antenna to form a transmitting and receiving element antenna, and a plurality of element antennas located between the two element antennas are defined as a receiving element antenna,
Radar transmission waves are sequentially transmitted from one transmitting / receiving element antenna, and each reflected radio wave is received in the order of the one transmitting / receiving element antenna, the receiving element antenna in the corresponding order, and the other transmitting / receiving element antenna, and then The transmitting and receiving cycle is controlled so that radar transmission waves are sequentially transmitted from the other transmitting / receiving element antenna and the respective reflected radio waves are received in the order of the corresponding receiving element antenna and the other transmitting / receiving element antenna. The radar device according to claim 1, wherein

One of two element antennas located at opposite ends of the array of array antennas is a transmitting element antenna, and the other is connected to a circulator to form a transmitting and receiving element antenna, and a plurality of elements located between the two element antennas The antenna is a receiving element antenna,
The transmission element antenna and the transmission / reception element antenna are supplied with transmission signals orthogonal to each other to transmit radar transmission waves at the same timing and sequentially, and receive the reflected radio waves by the reception element antennas in the order corresponding to the respective reflected radio waves. Then, the radar transmission wave is transmitted only from the transmission element antenna, and the transmission / reception cycle is controlled so that the reflected wave is received by the transmission / reception element antenna,
The radar according to claim 1, wherein after orthogonally receiving signals received by the receiving element antenna and the transmitting / receiving element antenna are demodulated, the demodulated signals are combined and processed as a synthetic aperture array signal. apparatus.

Two element antennas located at opposite ends of the array of array antennas are used as transmitting element antennas, and a plurality of element antennas located between the two transmitting element antennas are used as receiving element antennas,
Radar transmission waves are sequentially transmitted from one transmission element antenna, and the respective reflected radio waves are received by the reception element antennas in the corresponding order, and then the radar transmission waves are sequentially transmitted from the other transmission element antenna. 2. The radar apparatus according to claim 1, wherein a cycle of transmission and reception is controlled so that each reflected radio wave is received by the receiving element antennas in the corresponding order.

Using an array antenna in which a plurality of element antennas are arranged at predetermined intervals, radar transmission waves are sequentially transmitted at regular intervals, reflected radio waves from a target are received, and the received signals are combined to synthesize a synthetic aperture array signal. In a radar device that processes as
The array antenna comprises a plurality of sub-arrays each consisting of a predetermined number of element antennas provided with a phase shifter,
Two sub-arrays located at opposite ends of the array of the array antennas are used as transmission / reception sub-arrays each having a circulator connected to each element antenna to form a transmission / reception element antenna, and a plurality of sub-arrays located between the two sub-arrays are arranged. A receiving sub-array in which each element antenna is a receiving element antenna,
Radar transmission waves are sequentially transmitted from one transmitting / receiving sub-array, and the respective reflected radio waves are received in the order of the one transmitting / receiving sub-array itself, the receiving sub-array in the corresponding order and the other transmitting / receiving sub-array, and The transmitting / receiving cycle is controlled so that radar transmission waves are sequentially transmitted from the other transmitting / receiving sub-array, and the respective reflected radio waves are received in the order of the corresponding receiving sub-array and the other transmitting / receiving sub-array itself. ,
A radar antenna device, wherein a received signal received by an element antenna is combined for each sub-array, and the combined signals of the respective sub-arrays are further combined and processed as a synthetic aperture array signal.