JP3980172B2

JP3980172B2 - Broadband antenna

Info

Publication number: JP3980172B2
Application number: JP12852398A
Authority: JP
Inventors: 徹松岡; 圭二三本; 雅之中野
Original assignee: KDDI Corp; Nihon Dengyo Kosaku Co Ltd
Current assignee: KDDI Corp; Nihon Dengyo Kosaku Co Ltd
Priority date: 1998-05-12
Filing date: 1998-05-12
Publication date: 2007-09-26
Anticipated expiration: 2018-05-12
Also published as: JPH11330842A

Description

【０００１】
【発明の属する技術分野】
本発明は、広帯域アンテナに係わり、特に、移動通信の屋内中継装置に採用される小型アンテナ、あるいは広帯域特性が要求される基地局用アレイアンテナに適用して有効な技術に関する。
【０００２】
【従来の技術】
携帯電話等の移動通信では、電波が遮蔽される関係上、屋内での使用が制限されている。
そのため、駅等の公共施設の天井に中継装置を設け、屋内においても携帯電話を使用可能とすることが試みられている。
この中継装置に使用されるアンテナとしては、低姿勢で、かつ双方向指向特性のものが要求され、この要求を満足するものとして、例えば、図１８に示す半ループアンテナがある。
図１８は、従来の半ループアンテナの概略構成を示す斜視図である。
同図において、１１は放射素子を構成する半ループ状導電体であり、半ループ状導電体１１は、例えば、金属の線、条、管等の導電性のあるもので構成される。
この半ループ状導電体１１は、接地導電体１２に垂直な端子部領域と、接地導電体１２に平行な平行部領域とで構成される。
半ループ状導電体１１の一方の端子部領域は、給電点１３において接地導電体１２の裏面側に配設される同軸接栓（図示せず）の芯導電体と接続され、また、半ループ状導電体１１の他方の端子部領域は、接地導電体１２と電気的に接続される。
給電点１３から半ループ状導電体１１に沿った長さは、設計周波数ｆｏの約λｏ／２となるようにされる。
ここで、設計周波数ｆｏは、使用周波数帯域の中心周波数を意味し、また、λｏは、設計周波数ｆｏにおける波長を示す。
【０００３】
図１９は、図１８に示す半ループアンテナの一例のＸ−Ｙ面の電界成分の指向特性を示すグラフである。
なお、図１９では、半ループ状導電体１１として、断面形状が円で、その半径が０．５ｍｍの導電体を使用し、また、半ループ状導電体１１の端子部領域の長さ（図１８に示すＬ_V）を４０ｍｍ、水平領域の長さ（図１８に示すＬ_H）を１１４ｍｍとし、さらに、接地導電体１３を、一辺が１ｍの正方形とした場合の、図１８に示す座標系における、Ｘ−Ｙ面の電界成分の指向特性を示すグラフである。
この図１９のグラフから分かるように、図１８に示す半ループアンテナは、Ｘ軸上に指向性を有する双方向指向特性を有している。
図２０は、図１９と同一条件下での図１８に示す半ループアンテナの一例のＶＳＷＲの周波数特性を示すグラフである。
この図２０から分かるように、図１８に示す半ループアンテナにおける、ＶＳＷＲ１．５以下の比帯域幅（規定の値に合致する帯域幅とその帯域の中心周波数との比）は５．４％である。
【０００４】
【発明が解決しようとする課題】
前記した如く、図１８に示す従来の半ループアンテナは、低姿勢で、かつ双方向指向特性を有している。
しかしながら、前記従来の半ループアンテナの帯域特性はそれほど広帯域ではなく、前記従来の半ループアンテナは、周波数分割多重のように送信帯域と受信帯域とを共用して使用する携帯電話システム、あるいは今後予想される高速大容量伝送のために、広帯域に渡って周波数特性の変化が少ない伝送系が要求されるシステムに使用される中継器用アンテナには適していないという問題点があった。
【０００５】
本発明は、前記従来技術の問題点を解決するためになされたものであり、本発明の目的は、低姿勢で、かつ双方向指向特性を有し、従来より広帯域なアンテナを提供することにある。
【０００６】
また、本発明の他の目的は、高利得、かつ双方向指向特性を有し、従来より広帯域なアンテナを提供することにある。
【０００７】
本発明の前記ならびにその他の目的と新規な特徴は、本明細書の記述及び添付図面によって明らかにする。
【０００８】
【課題を解決するための手段】
本願において開示される発明のうち、代表的なものの概要を簡単に説明すれば、下記の通りである。
【０００９】
即ち、本発明の広帯域アンテナは、接地導電体と、前記接地導電体上に配置される誘電体基板と、前記誘電体基板の一表面に形成され、両端部が前記接地導電体と電気的に接続される第２導電体で構成される無給電素子と、前記誘電体基板の一表面の反対側の面に形成され、一端部が開放端とされる第１導電体と、前記第１導電体の一端部から所定距離離れた一点と給電点とを接続する給電導電体とで構成される励振素子とを有し、前記第１導電体の他端部は、前記第２導電体の一方の端部を含む第１端子部領域、あるいは他方の端部を含む第２端子部領域と高周波的に結合され、前記接地導電体と電気的に接続される広帯域アンテナであって、前記給電導電体は、給電用の導電体に接続され、前記給電用の導電体は、前記第２導電体の少なくとも一部の投影領域内を通って、前記第２導電体の第２端子部領域、あるいは第１端子部領域の端部に設けられた一点まで延長されていることを特徴とする。
【００１０】
また、本発明の広帯域アンテナでは、前記第１導電体は、前記接地導電体に略垂直に設置される前記他端部を含む端子部領域と、前記接地導電体に略平行に設置される前記一端部を含む平行部領域とで構成され、前記給電導電体は、前記接地導電体に略垂直に設置され、前記第２導電体は、前記接地導電体に略垂直に設置される前記第１端子部領域と、前記接地導電体に略垂直に設置される前記第２端子部領域と、前記接地導電体に略平行に設置される平行部領域とで構成されることを特徴とする。
また、本発明の広帯域アンテナでは、前記接地導電体は、第１導電体、または第２導電体を頂角とする優角コーナ状、あるいは第１導電体、または第２導電体の設置位置を円弧外とする円弧状に形成されることを特徴とする。
【００１１】
また、本発明の広帯域アンテナは、両端部が開放端とされるループ状の第１導電体と、前記第１導電体の一端部から所定距離離れた一点と給電点とを接続する第１給電導電体と、前記第１導電体の他端部から所定距離離れた一点と給電点とを接続する第２給電導電体とで構成される励振素子と、一部分が、前記第１導電体の一部分と略平行に設置されるループ状の第２導電体で構成される無給電素子とを有し、前記第２導電体は、前記第２導電体における前記第１導電体の両開放端の間の部分が接地され、一端部に切り込みを有し、他端部が前記第２導電体の接地された部分に接続される接地導電体と、平衡−不平衡変換回路で構成される給電回路とを有し、前記接地導電体は、前記平衡−不平衡変換回路の一部を構成し、前記切り込みによる分割された部分が、それぞれ前記第１給電導電体と第２給電導電体に接続されることを特徴とする。
【００１２】
また、本発明の広帯域アンテナは、ループ状の第３導電体で構成される無給電素子と、一端部が開放端とされ、他端部が互いに前記第３導電体に接続される第１導電体および第２導電体と、前記第１導電体の一端部から所定距離離れた一点と給電点とを接続する第１給電導電体と、前記第２導電体の一端部から所定距離離れた一点と給電点とを接続する第２給電導電体とで構成される励振素子とを有し、前記第３導電体は、前記第１導電体および前記第２導電体の開放端と対向する部分が接地され、前記第３導電体の一部分は、前記第１導電体および第２導電体の一部分と略平行に設置されることを特徴とする。
【００１３】
【発明の実施の形態】
以下、図面を参照して本発明の実施の形態を詳細に説明する。
【００１４】
なお、実施の形態を説明するための全図において、同一機能を有するものは同一符号を付け、その繰り返しの説明は省略する。
【００１５】
［実施の形態１］
図１は、本発明の実施の形態１の広帯域アンテナの概略構成を示す斜視図である。
同図において、２₁は放射素子を構成する逆Ｌ字形状のＬ字形導電体（本発明の第１導電体）であり、このＬ字形導電体２₁は、本発明の第１導電体を構成し、金属の線、条、板、管等で構成される。
Ｌ字形導電体２₁の一端部は開放端とされ、また、他端部は接地導電体３と電気的（または高周波的）に接続される。
このＬ字形導電体２₁は、接地導電体３と略垂直に設置される他端部を含む端子部領域と、接地導電体３と略平行に設置される一端部を含む平行部領域とで構成される。
２₂は給電導電体であり、この給電導電体２₂は、一方の端部が、給電点４において接地導電体３の裏面側に配設される同軸接栓（図示せず）の芯導体と接続され、また、他方の端部が、接地導電体３に略平行関係にあるＬ字形導電体２₁の一端部から所定距離離れた一点と接続される。
なお、このＬ字形導電体２₁の一端部から所定距離離れた一点は、接続される同軸線路のインピーダンス値により選定される。
この場合に、同軸接栓の芯導体を、接地導電体３に形成された給電点４に対応する穴を貫通させた後給電導電体２₂に接続するか、または、芯導体をそのまま延長して、Ｌ字形導電体２₁に直接接続して給電導電体２₂の代用としてもよい。
接地導電体３は、導電体の面であれば、格子や適宜打ち抜いた金属板（所謂パンチメタル）を使用してもよい。
前記した如く、給電点４の背面には同軸接栓が取り付けられており、この同軸接栓の外導体は接地導電体３に接続される。
【００１６】
本実施の形態において、給電点４からＬ字形導電体２₁の開放端となる一端部までの長さ（図１に示すＬ_A）は使用中心周波数の略λｏ／４に選択される。
１は枠状の半ループ状導電体（本発明の第２導電体）であり、この半ループ状導電体１は、本発明の第２導電体を構成する。この半ループ状導電体１は、コの字形に形成され、半ループ状導電体１の両端部は接地導電体３と電気的（または高周波的）に接続される。
この半ループ状導電体１は、接地導電体３と略垂直に設置される一端部を含む第１の端子部領域と、接地導電体３と略垂直に設置される他端部を含む第２の端子部領域と、接地導電体３と略平行に設置される平行部領域とで構成される。
また、半ループ状導電体１の一方の端子部領域は、Ｌ字形導電体２₁の端子部領域、あるいは給電導電体２₂と略平行に設置される。
ここで、半ループ状導電体１の長さは、使用中心周波数の略λｏ／２に選択される。
【００１７】
図２は、本実施の形態の広帯域アンテナの一例のＶＳＷＲの周波数特性を示すグラフである。
この図２のグラフは、半ループ状導電体１、Ｌ字形導電体２₁および給電導電体２₂として、断面形状が円で、その半径が０．５ｍｍの導電体を使用し、半ループ状導電体１の端子部領域の長さ（図１に示すＬ_V）を４０ｍｍ、水平部領域の長さ（図１に示すＬ_H）を１１４ｍｍとし、また、Ｌ字形導電体２₁の端子部領域の長さ（図１に示すＬ_C）を２４ｍｍ、水平部領域の長さ（図１に示すＬ_B）を１０６ｍｍとし、また、給電点４をＬ字形導電体２₁の端子部領域と平行に４５ｍｍ離して設置し、また、Ｌ字形導電体２₁の端子部領域と半ループ状導電体１の端子部領域の一方との間隔が２ｍｍとなるように設置し、さらに、接地導電体１３を、一辺が１ｍの正方形とした場合の、ＶＳＷＲの周波数特性を示すものである。
この図２のグラフから分かるように、本実施の形態の広帯域アンテナでは、ＶＳＷＲが１．５以下の比帯域幅は約１７％となっている。
【００１８】
図３〜図５は、図２と同一条件下での本実施の形態の広帯域アンテナの一例における、周波数が、それぞれ８４０ＭＨｚ、９２０ＭＨｚ、および１０００ＭＨｚのときの、図１に示す座標系における、Ｘ−Ｙ面の電界成分の指向特性を示すグラフである。
これらのグラフから分かるように、本願実施の形態の広帯域アンテナは、広帯域に渡りＸ軸上に指向特性を有する双方向指向特性となっている。
このように、本実施の形態の広帯域アンテナによれば、半ループ状導電体１の端子部領域の一方と、Ｌ字形導電体２₁の端子部領域とを、電磁的に結合させることにより、半ループ状導電体１が無給電素子として機能し、２つの共振回路による複同調回路の原理により広帯域特性を実現することができる。
これにより、本実施の形態の広帯域アンテナによれば、低姿勢で、かつ双方向指向特性を有し、従来よりも帯域特性を広帯域とすることができる。
【００１９】
なお、本実施の形態の広帯域アンテナにおいて、半ループ状導電体１の形状は、コの字状に限定されるものではなく、例えば、図６（ａ）に示すような円弧状でもよく、さらに、図６（ｂ）に示すように、半ループ状導電体１の端子部領域は、必ずしも接地導電体３と垂直でなくてもよい。
この場合に、半ループ状導電体１の端子部領域の一方と、Ｌ字形導電体２₁の端子部領域とを電磁的に結合させて、広帯域特性を実現するために、Ｌ字形導電体２₁の端子部領域の形状もまた半ループ状導電体１の形状と相似形であることが望ましい。
また、本実施の形態の広帯域アンテナおいて、図７（ａ）〜（ｃ）に示すように、半ループ状導電体１の端子部領域と、給電導電体２₂とを電磁的に結合させてもよく、また、半ループ状導電体１の端子部領域は、どちらの領域でも構わない。
【００２０】
さらに、本実施の形態の広帯域アンテナおいて、接地導電体３のは平面の場合について説明したが、これに限定されず、例えば、図８（ａ）に示すように、半ループ状導電体１、Ｌ字形導電体２₁および給電導電体２₂を頂角とする優角コーナ状に折り曲げたり、また、図８（ｂ）に示すように、図８（ａ）に示す優角の辺を弧に代えた円弧状としてもよい。
接地導電体３として、図８（ａ）、図８（ｂ）に示す接地導電体３を使用することにより、図９に示すように、図１に示す座標系における、Ｘ−Ｚ面における指向特性の最大方向をＸ軸に方向に近づけることができるため、本実施の形態のアンテナを天井等に設置した場合の無線エリアを変化させることができる。
なお、図９において、３０ａは、コーナ状に折り曲げられた接地導電体３ａを使用したときの指向特性を、また、３０ｂは、平面形状の接地導電体３ｂを使用したときの指向特性を示す。
【００２１】
［実施の形態２］
図１０は、本発明の実施の形態２の広帯域アンテナの概略構成を示す斜視図である。
【００２２】
本実施の形態の広帯域アンテナは、誘電体基板５上に、プリント配線板による回路形成手法によるエッチングを施し、半ループ状導電体１、Ｌ字形導電体２₁および給電導電体２₂を形成した点で、前記実施の形態１と相違する。
本実施の形態の広帯域アンテナにおいて、誘電体基板５の厚さが使用波長（λｏ）に比して十分薄いものであれば、前記実施の形態１のアンテナの特性と等価な特性を得ることができる。
なお、図１０において、４₁は同軸接栓の芯導体を示す。
【００２３】
［実施の形態３］
図１１は、本発明の実施の形態３の広帯域アンテナの概略構成を示す図である。
【００２４】
本実施の形態の広帯域アンテナも、誘電体基板５上に半ループ状導電体１、Ｌ字形導電体２₁、および給電導電体２₂を形成したものであるが、誘電体基板５の表面および裏面に半ループ状導電体１、Ｌ字形導電体２₁、および給電導電体２₂を形成した点で、前記実施の形態２と相違する。
図１１（ａ）は、誘電体基板１の表面（または裏面）を示すもので、実線は、誘電体基板５の輪郭、および半ループ状導電体１を示し、この半ループ状導電体１は、マイクロストリップ線路のアース導電体を兼用している。
また、図１１（ｂ）は、誘電体基板１の裏面（または表面）を示すもので、実線は、誘電体基板５の輪郭、およびＬ字形導電体２₁、給電導電体２₂、給電のためにマイクロストリップ線路２₃、および結合のためのマイクロストリップ線路２₄を示している。
なお、図１１（ａ）、図１１（ｂ）の点線は、誘電体基板５の裏側に形成される半ループ状導電体１、Ｌ字形導電体２₁、給電導電体２₂、給電や結合のためのマイクロストリップ線路（２₃，２₄）を示している。
【００２５】
本実施の形態の広帯域アンテナにおいて、給電のためのマイクロストリップ線路２₃に入力された電力は、半ループ状導電体１をマイクロストリップ線路のアース導電体とするマイクロストリップ線路２₃上を伝送し、Ｌ字形導電体２₁、給電導電体２₂からなる所謂逆Ｆ形アンテナを励振する。
Ｌ字形導電体２₁の延長上に接続された先端部が開放端とされるマイクロストリップ線路２₄は、１／４波長結合線路を構成し、このマイクロストリップ線路２₄により、Ｌ字形導電体２₁の端部と、半ループ状導電体１とが、電磁結合で高周波的に接続される。
本実施の形態のアンテナによれば、Ｌ字形導電体２₁と接地導電体３との機械的な接続が不要となり、また、給電点４と半ループ状導電体１との接続点も共通化できることから、製造が容易となる他、信頼性を向上させることできる。
【００２６】
［実施の形態４］
図１２は、本発明の実施の形態４の広帯域アンテナの概略構成を示す図である。
同図において、６は同軸接栓、７は平衡−不平衡変換器、２０はループ状導電体、２１は両端部が開放端とされるコの字形の半ループ状導電体、２４，２５は給電導電体である。
本実施の形態の広帯域アンテナは、前記実施の形態２に示す広帯域アンテナと、接地導電体３側の端面について前記実施の形態２に示す広帯域アンテナと線対称の広帯域アンテナとを、誘電体基板５に形成した広帯域アンテナである。
【００２７】
本実施の形態の広帯域アンテナによれば、誘電体基板５の面に対して鉛直な方向で強い放射を行うことができるので、これにより、本実施の形態の広帯域アンテナによれば、高利得、かつ双方向指向特性を有し、従来より帯域特性を広帯域とすることができる。
したがって、本実施の形態の広帯域アンテナは、広帯域で双方向に無線ゾーンを必要とするアレイアンテナのアンテナ素子として有用であるばかりか、誘電体基板５の面に平行となるように導電性の平面反射板、コーナ形反射板等の反射器を適宜設けることにより、広帯域で単一方向に無線ゾーンを必要とするアレイアンテナのアンテナ素子として有用である。
【００２８】
図１３は、本実施の形態の広帯域アンテナをアンテナ素子として利用するアレイアンテナの一例を示す図である。
図１３に示すように、図１２に示す広帯域アンテナを配置することで、容易にアンテナの放射開口を広げることができるため、広帯域で高利得が要求されるアレイアンテナのアンテナ素子として有用である。
【００２９】
図１４は、本実施の形態の広帯域アンテナの他の例の概略構成を示す図である。
同図において、２２，２３は一端部が開放端とされるＬ字形状のＬ字形導電体である。
図１４に示す広帯域アンテナは、Ｌ字形導電体（２２，２３）の平行部領域が相対向するように、Ｌ字形導電体（２２，２３）を設置し、また、Ｌ字形導電体（２２，２３）の各他端部を、ループ状導電体２０に接続するようにしたものである。
図１４に示す広帯域アンテナにおいても、誘電体基板５の面に対して鉛直な方向で強い放射を行うことができる。
なお、図１２、図１３において、点線は、給電導電体（２４，２５）に給電するための線路を示す。
【００３０】
［実施の形態５］
図１５は、本発明の実施の形態５の広帯域アンテナの概略構成を示す斜視図である。
本実施の形態の広帯域アンテナは、双方向指向特性の程度を調整するために、半ループ状導電体１とＬ字形導電体２₁との平行部領域を、直角に曲げるようにした点で、前記実施の形態１と相違する。
図１６は、本実施の形態の広帯域アンテナの一例の、図１５に示す座標系における、Ｘ−Ｙ面の電界成分の指向特性を示すグラフである。
この図１６のグラフから分かるように、本実施の形態の広帯域アンテナによれば、指向特性の最大放射方向が単一化されるため、無線ゾーンの規模や方向に合わせた調整が可能となる。
なお、本実施の形態の広帯域アンテナにおいて、半ループ状導電体１とＬ字形導電体２₁との平行部領域を直角に曲げる代わりに、図１７に示すように、半ループ状導電体１とＬ字形導電体２₁との平行部領域を円弧状に形成するようにしてもよい。
【００３１】
本発明者によってなされた発明を、前記実施の形態に基づき具体的に説明したが、本発明は、前記実施の形態に限定されるものではなく、その要旨を逸脱しない範囲において種々変更可能であることは勿論である。
【００３２】
【発明の効果】
本願において開示される発明のうち代表的なものによって得られる効果を簡単に説明すれば、下記の通りである。
【００３３】
（１）本発明によれば、第２導電体の端子部領域の一方と、第１導電体の端子部領域、または給電導電体を電磁的に結合させることにより、第２導電体を無給電素子として機能させるようにしたので、従来よりも帯域特性を広帯域とすることができ、これにより、低姿勢で、かつ双方向指向特性を有し、従来よりも広帯域な広帯域アンテナを提供することが可能となる。
【００３４】
（２）本発明によれば、前記低姿勢で、かつ双方向指向特性を有する広帯域アンテナと、当該広帯域アンテナと線対称の広帯域アンテナとを、誘電体基板に形成するようにしたので、誘電体基板の面に対して鉛直な方向で強い放射を行うことができ、これにより、高利得、かつ双方向指向特性を有し、従来よりも広帯域な広帯域アンテナを提供することが可能となる。
【図面の簡単な説明】
【図１】本発明の実施の形態１の広帯域アンテナの概略構成を示す斜視図である。
【図２】本実施の形態１の広帯域アンテナの一例のＶＳＷＲの周波数特性を示すグラフである。
【図３】本実施の形態１の広帯域アンテナの一例の、周波数が８４０ＭＨｚときのＸ−Ｙ面の電界成分の指向特性を示すグラフである。
【図４】本実施の形態１の広帯域アンテナの一例の、周波数が９２０ＭＨｚのときのＸ−Ｙ面の電界成分の指向特性を示すグラフである。
【図５】本実施の形態１の広帯域アンテナの一例の、周波数が１０００ＭＨｚのときのＸ−Ｙ面の電界成分の指向特性を示すグラフである。
【図６】本実施の形態１の広帯域アンテナの他の例を示す模式図である。
【図７】本実施の形態１の広帯域アンテナの他の例を示す模式図である。
【図８】本実施の形態１の広帯域アンテナにおける接地導電体の他の例を示す模式図である。
【図９】接地導電体として、図８に示す接地導電体を使用したときのＸ−Ｚ面における指向特性を示す模式図である。
【図１０】本発明の実施の形態２の広帯域アンテナの概略構成を示す斜視図である。
【図１１】本発明の実施の形態３の広帯域アンテナの概略構成を示す図である。
【図１２】本発明の実施の形態４の広帯域アンテナの概略構成を示す図である。
【図１３】本発明の実施の形態４の広帯域アンテナをアンテナ素子として利用するアレイアンテナの一例を示す図である。
【図１４】本発明の実施の形態４の広帯域アンテナの他の例の概略構成を示す図である。
【図１５】本発明の実施の形態５の広帯域アンテナの概略構成を示す斜視図である。
【図１６】本実施の形態５の広帯域アンテナの一例のＸ−Ｙ面の電界成分の指向特性を示すグラフである。
【図１７】本発明の実施の形態５の広帯域アンテナの他の例の概略構成を示す斜視図である。
【図１８】従来の半ループアンテナの概略構成を示す斜視図である。
【図１９】図１８に示す半ループアンテナの一例のＸ−Ｙ面の電界成分の指向特性を示すグラフである。
【図２０】図１８に示す半ループアンテナの一例のＶＳＷＲの周波数特性を示すグラフである。
【符号の説明】
１，１１，…半ループ状導電体、２_１，２２，２３…Ｌ字形導電体、２_２，２４，２５…給電導電体、３，３ａ，３ｂ，１２…接地導電体、４，１３…給電点、４1 …芯導体、５…誘電体基板、６…同軸接栓、７…平衡−不平衡変換器、２０…ループ状導電体。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a wideband antenna, and more particularly to a technique that is effective when applied to a small antenna employed in an indoor repeater for mobile communication or an array antenna for a base station that requires wideband characteristics.
[0002]
[Prior art]
In mobile communication such as a cellular phone, indoor use is restricted because radio waves are shielded.
Therefore, an attempt is made to provide a relay device on the ceiling of a public facility such as a station so that a mobile phone can be used indoors.
As an antenna used for this relay apparatus, a low-profile and bidirectional directivity characteristic is required, and a half-loop antenna shown in FIG. 18, for example, satisfies this requirement.
FIG. 18 is a perspective view showing a schematic configuration of a conventional half-loop antenna.
In the figure, reference numeral 11 denotes a half-loop conductor constituting the radiating element. The half-loop conductor 11 is made of a conductive material such as a metal wire, strip, or tube.
The half-loop conductor 11 includes a terminal area that is perpendicular to the ground conductor 12 and a parallel area that is parallel to the ground conductor 12.
One terminal region of the half-loop conductor 11 is connected to a core conductor of a coaxial plug (not shown) disposed on the back side of the ground conductor 12 at the feeding point 13. The other terminal area of the conductor 11 is electrically connected to the ground conductor 12.
The length along the half-loop conductor 11 from the feeding point 13 is set to approximately λo / 2 of the design frequency fo.
Here, the design frequency fo means the center frequency of the used frequency band, and λo indicates the wavelength at the design frequency fo.
[0003]
FIG. 19 is a graph showing the directivity characteristics of the electric field component on the XY plane of an example of the half-loop antenna shown in FIG.
In FIG. 19, a conductor having a circular cross-section and a radius of 0.5 mm is used as the semi-loop conductor 11, and the length of the terminal region of the half-loop conductor 11 (see FIG. 19). L _V) of 40mm shown in 18, and the length of the horizontal region (L _H shown in FIG. 18) and 114 mm, further, in the case where the ground conductor 13, one side was a square of 1 m, the coordinate system shown in FIG. 18 It is a graph which shows the directivity characteristic of the electric field component of XY plane in FIG.
As can be seen from the graph of FIG. 19, the half-loop antenna shown in FIG. 18 has a bidirectional directivity characteristic having directivity on the X axis.
FIG. 20 is a graph showing the frequency characteristics of the VSWR of an example of the half-loop antenna shown in FIG. 18 under the same conditions as FIG.
As can be seen from FIG. 20, in the half-loop antenna shown in FIG. 18, the relative bandwidth of VSWR 1.5 or less (the ratio between the bandwidth matching the specified value and the center frequency of the bandwidth) is 5.4%. is there.
[0004]
[Problems to be solved by the invention]
As described above, the conventional half-loop antenna shown in FIG. 18 has a low attitude and bidirectional directivity.
However, the bandwidth characteristics of the conventional half-loop antenna are not so wide, and the conventional half-loop antenna is a cellular phone system that uses a transmission band and a reception band in common, such as frequency division multiplexing, or is expected in the future. Due to the high-speed and large-capacity transmission, there is a problem that it is not suitable for a repeater antenna used in a system that requires a transmission system with little change in frequency characteristics over a wide band.
[0005]
The present invention has been made in order to solve the above-described problems of the prior art, and an object of the present invention is to provide an antenna having a low attitude and a bidirectional directivity, which is wider than that of the conventional antenna. is there.
[0006]
Another object of the present invention is to provide an antenna having a high gain and bidirectional directivity and a wider bandwidth than the conventional one.
[0007]
The above and other objects and novel features of the present invention will become apparent from the description of this specification and the accompanying drawings.
[0008]
[Means for Solving the Problems]
Of the inventions disclosed in this application, the outline of typical ones will be briefly described as follows.
[0009]
That is, the broadband antenna of the present invention is formed on a ground conductor, a dielectric substrate disposed on the ground conductor, and one surface of the dielectric substrate, and both ends thereof are electrically connected to the ground conductor. and the parasitic element consisting of the second conductor to be connected, the formed on the opposite side of the dielectric a surface of a substrate, a first conductor having one end Ru is an open end, said first conductive An excitation element composed of a feeding conductor connecting a feeding point and a point separated from one end of the body by a predetermined distance, and the other end of the first conductor is one of the second conductors. A wideband antenna that is coupled in high frequency with a first terminal portion region that includes an end of the first terminal region, or a second terminal portion region that includes the other end portion, and is electrically connected to the ground conductor. body is connected to the conductor of the power supply, conductors for the power supply, the small of the second conductor And also through a portion of the projection area, characterized in that it is extended to a point provided at an end of the second terminal region of the second conductor or the first terminal region.
[0010]
In the wideband antenna of the present invention, the first conductor is provided in a terminal part region including the other end part that is installed substantially perpendicularly to the ground conductor, and in which the first conductor is installed substantially parallel to the ground conductor. is constituted by a parallel portion region including the one end portion, before Symbol feeding conductor, the disposed substantially perpendicular to the ground conductor, before Symbol second conductor is disposed substantially perpendicular to the ground conductor The first terminal portion region, the second terminal portion region disposed substantially perpendicular to the ground conductor, and a parallel portion region disposed substantially parallel to the ground conductor. And
In the broadband antenna according to the present invention, the ground conductor may be a corner of the first conductor or a second conductor having a vertex angle, or the installation position of the first conductor or the second conductor. It is formed in a circular arc shape outside the circular arc.
[0011]
In the broadband antenna of the present invention, the first feeding that connects the feeding point to a loop-shaped first conductor whose both ends are open ends and a point separated from one end of the first conductor by a predetermined distance. An excitation element comprising a conductor and a second feeding conductor that connects a feeding point with a point that is a predetermined distance away from the other end of the first conductor, and a part thereof is a part of the first conductor When and a parasitic element formed of a second conductor loop which is substantially parallel to the installation, the second electrical conductors between the two open ends of the first conductor in the second conductor A ground conductor having a notch at one end and a ground conductor connected at the other end to the grounded portion of the second conductor, and a power supply circuit composed of a balanced-unbalanced conversion circuit have the grounded conductive, the balanced - form part of the unbalanced conversion circuit, the cut Divided portions, to each of the first power supply conductor and characterized by being connected to the second feed conductor.
[0012]
In addition, the broadband antenna of the present invention includes a parasitic element formed of a loop-shaped third conductor, and a first conductor in which one end is an open end and the other ends are connected to the third conductor. And a second conductor, a first feeding conductor connecting a feeding point to a point separated from one end of the first conductor, and a point separated from the one end of the second conductor. And a second feeding conductor connecting the feeding point to the feeding point, and the third conductor has a portion facing the open ends of the first conductor and the second conductor. The third conductor is grounded, and a part of the third conductor is disposed substantially parallel to a part of the first conductor and the second conductor.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
[0014]
Note that components having the same function are denoted by the same reference symbols throughout the drawings for describing the embodiment, and the repetitive description thereof will be omitted.
[0015]
[Embodiment 1]
FIG. 1 is a perspective view showing a schematic configuration of a wideband antenna according to Embodiment 1 of the present invention.
In the figure, 2 ₁ is L-shaped conductor inverted L-shape constituting the radiating element (first conductor of the present invention), this L-shaped conductor 2 _1, the first conductor of the present invention Consists of metal wires, strips, plates, tubes, etc.
L-shaped conductor 2 ₁ at one end is an open end, also, the other end is connected to an electrical ground conductor 3 (or high frequency).
In this L-shaped conductor 2 ₁ includes a terminal region that includes the other portion being disposed substantially perpendicular to the ground conductor 3, a parallel region including the one end portion which is substantially parallel to the installation and the ground conductor 3 Composed.
2 ₂ is a feeder conductor, the feeder conductors 2 ₂ has one end, the core conductor of the coaxial connector (not shown) disposed on the back side of the ground conductor 3 at the feed point 4 is connected to, and the other end is connected to a point spaced a predetermined distance from the L-shaped conductor 2 ₁ one end which is in substantially parallel relation to the ground conductor 3.
Incidentally, a point a predetermined distance from one end of the L-shaped conductor 2 ₁ is selected by the impedance value of the coaxial line connected.
In this case, the core conductor of the coaxial connector, to connect to the power feeding conductor 2 ₂ After through holes corresponding to the feeding point 4, which is formed on the ground conductor 3, or, as it extends the core conductor Thus, the power supply conductor 2 ₂ may be substituted by directly connecting to the L-shaped conductor 2 ₁ .
The grounding conductor 3 may be a grid or a suitably punched metal plate (so-called punch metal) as long as it is a conductor surface.
As described above, the coaxial plug is attached to the back surface of the feeding point 4, and the outer conductor of the coaxial plug is connected to the ground conductor 3.
[0016]
In this embodiment, the length from the feeding point 4 to the end portion to be L-shaped conductor 2 ₁ open ends (L _A shown in FIG. 1) is selected to substantially .lamda.o / 4 use the center frequency.
Reference numeral 1 denotes a frame-like half-loop conductor (second conductor of the present invention), and this half-loop conductor 1 constitutes the second conductor of the present invention. The half-loop conductor 1 is formed in a U-shape, and both ends of the half-loop conductor 1 are electrically (or high-frequency) connected to the ground conductor 3.
The half-loop conductor 1 includes a first terminal portion region including one end portion installed substantially perpendicular to the ground conductor 3, and a second end portion including the other end portion installed substantially perpendicular to the ground conductor 3. Terminal portion region and a parallel portion region installed substantially parallel to the ground conductor 3.
Further, one terminal region of the half-loop-shaped conductor 1, L-shaped conductor 2 ₁ terminal region, or is substantially parallel to the installation and the feeding conductor 2 _2.
Here, the length of the half-loop conductor 1 is selected to be approximately λo / 2 of the use center frequency.
[0017]
FIG. 2 is a graph showing the frequency characteristics of VSWR as an example of the broadband antenna according to the present embodiment.
Graph of Figure 2, as a semi-loop-shaped conductor 1, L-shaped conductor 2 ₁ and the power supply conductors 2 _2, a circle cross-sectional shape, by using the conductor of the radius of 0.5 mm, a semi-looped the length of the terminal region of the conductor 1 40 mm to (L _V shown in FIG. 1), and the length of the horizontal section area (L _H shown in FIG. 1) and 114 mm, also, L-shaped conductor 2 ₁ of the terminal portion the length of the region (L _C shown in FIG. 1) 24 mm, length of the horizontal section area (L _B shown in FIG. 1) and 106 mm, also, the feed point 4 L-shaped conductor 2 ₁ terminal region Installed so that the distance between the terminal part region of the L-shaped conductor 21 and _one of the terminal part regions of the half-loop conductor 1 is 2 mm, and the ground conductor. 13 shows the frequency characteristic of VSWR when 13 is a square with a side of 1 m.
As can be seen from the graph of FIG. 2, in the wideband antenna of the present embodiment, the specific bandwidth when the VSWR is 1.5 or less is about 17%.
[0018]
3 to FIG. 5 are X− in the coordinate system shown in FIG. 1 when the frequencies are 840 MHz, 920 MHz, and 1000 MHz, respectively, in an example of the wideband antenna of the present embodiment under the same conditions as FIG. 2. It is a graph which shows the directivity characteristic of the electric field component of a Y surface.
As can be seen from these graphs, the wideband antenna of the present embodiment has a bidirectional directivity characteristic having a directivity characteristic on the X axis over a wide band.
Thus, according to the antenna of the present embodiment, one of the terminal regions of the half-loop-shaped conductor 1, and the L-shaped conductor 2 ₁ terminal region, by electromagnetically coupling, The half-loop conductor 1 functions as a parasitic element, and a broadband characteristic can be realized by the principle of a double-tuned circuit using two resonance circuits.
Thereby, according to the wideband antenna of this Embodiment, it has a low attitude | position and bidirectional | two-way directional characteristics, and can make a band characteristic into a broadband rather than before.
[0019]
In the wideband antenna of the present embodiment, the shape of the half-loop conductor 1 is not limited to the U-shape, and may be, for example, an arc shape as shown in FIG. As shown in FIG. 6B, the terminal area of the half loop conductor 1 is not necessarily perpendicular to the ground conductor 3.
In this case, one of a half loop conductor 1 terminal region, and electromagnetically coupled to form an L-shaped conductor 2 ₁ terminal region, in order to realize a wide band characteristic, L-shaped conductor 2 It is desirable that the shape of the terminal area of ₁ is also similar to the shape of the semi-loop conductor 1.
Also, keep the antenna of the present embodiment, as shown in FIG. 7 (a) ~ (c) , a terminal region of the half-loop-shaped conductor 1, electromagnetically coupled and power feeding conductor 2 ₂ In addition, the terminal portion region of the half-loop conductor 1 may be either region.
[0020]
Furthermore, in the broadband antenna of the present embodiment, the case where the ground conductor 3 is a plane has been described. However, the present invention is not limited to this. For example, as shown in FIG. , or bent L-shaped conductor 2 ₁ and the power supply conductors 2 ₂ reflex angle corner shape and vertex angle, and as shown in FIG. 8 (b), the edges of the reflex angle shown in Fig. 8 (a) An arc shape instead of an arc may be used.
By using the grounding conductor 3 shown in FIGS. 8A and 8B as the grounding conductor 3, as shown in FIG. 9, the directivity in the XZ plane in the coordinate system shown in FIG. Since the maximum direction of the characteristics can be made closer to the X axis, the radio area when the antenna of this embodiment is installed on a ceiling or the like can be changed.
In FIG. 9, 30a indicates the directivity when the ground conductor 3a bent in a corner is used, and 30b indicates the directivity when the planar ground conductor 3b is used.
[0021]
[Embodiment 2]
FIG. 10 is a perspective view showing a schematic configuration of the broadband antenna according to the second embodiment of the present invention.
[0022]
In the broadband antenna according to the present embodiment, etching is performed on a dielectric substrate 5 by a circuit forming method using a printed wiring board to form a half-loop conductor 1, an L-shaped conductor 2 ₁ and a feeding conductor 2 ₂ . This is different from the first embodiment.
In the broadband antenna of the present embodiment, if the thickness of the dielectric substrate 5 is sufficiently thinner than the wavelength used (λo), characteristics equivalent to those of the antenna of the first embodiment can be obtained. it can.
In FIG. 10, 4 ₁ represents the core conductor of the coaxial connector.
[0023]
[Embodiment 3]
FIG. 11 is a diagram showing a schematic configuration of the wideband antenna according to the third embodiment of the present invention.
[0024]
The broadband antenna according to the present embodiment is also the one in which the half loop conductor 1, the L-shaped conductor 2 ₁ , and the feeding conductor 2 ₂ are formed on the dielectric substrate 5, but the surface of the dielectric substrate 5 and The second embodiment is different from the second embodiment in that a semi-loop conductor 1, an L-shaped conductor 2 ₁ , and a feeding conductor 2 ₂ are formed on the back surface.
FIG. 11A shows the front surface (or back surface) of the dielectric substrate 1, and the solid line shows the outline of the dielectric substrate 5 and the half-loop conductor 1, and the half-loop conductor 1 is The earth conductor of the microstrip line is also used.
FIG. 11B shows the back surface (or front surface) of the dielectric substrate 1, and the solid line shows the contour of the dielectric substrate 5, the L-shaped conductor 2 ₁ , the feeding conductor 2 ₂ , For this purpose, a microstrip line 2 ₃ and a microstrip line 2 ₄ for coupling are shown.
Note that the dotted lines in FIGS. 11A and 11B indicate the half loop conductor 1, L-shaped conductor 2 ₁ , feeding conductor 2 ₂ , feeding and coupling formed on the back side of the dielectric substrate 5. The microstrip lines (2 ₃ , 2 ₄ ) for are shown.
[0025]
In the wideband antenna of the present embodiment, the power input to the microstrip line 2 ₃ for feeding is transmitted on the microstrip line 2 ₃ using the half-loop conductor 1 as the ground conductor of the microstrip line. A so-called inverted F-shaped antenna composed of an L-shaped conductor 2 ₁ and a feeding conductor 2 ₂ is excited.
Microstrip line 2 ₄ connected tip on the extension of the L-shaped conductor 2 ₁ is an open end constitutes a 1/4-wavelength coupling line, a microstrip line 2 _4, L-shaped conductor and 2 ₁ end, half-loop-like conductor 1 and is high-frequency connected by electromagnetic coupling.
According to the antenna of the present embodiment, the mechanical connection between the L-shaped conductor 2 ₁ and the grounding conductor 3 will not be required, sharing also a connection point between the feeding point 4 and the half-loop-shaped conductor 1 As a result, manufacturing is facilitated and reliability can be improved.
[0026]
[Embodiment 4]
FIG. 12 is a diagram showing a schematic configuration of the wideband antenna according to the fourth embodiment of the present invention.
In the figure, 6 is a coaxial plug, 7 is a balance - unbalance converter, 20 is a loop conductor, 21 is a U-shaped semi-loop conductor with both ends open, 24 and 25 are It is a feeding conductor.
The broadband antenna according to the present embodiment includes the broadband antenna shown in the second embodiment, the broadband antenna shown in the second embodiment with respect to the end surface on the side of the ground conductor 3, and the broadband antenna that is symmetric with respect to the dielectric substrate 5. It is a broadband antenna formed in
[0027]
According to the wideband antenna of the present embodiment, strong radiation can be performed in a direction perpendicular to the surface of the dielectric substrate 5, so that, according to the wideband antenna of the present embodiment, high gain, In addition, it has bidirectional directivity, and the bandwidth can be made wider than before.
Therefore, the wideband antenna of the present embodiment is not only useful as an antenna element of an array antenna that requires a wideband and bidirectional radio zone, but also a conductive plane so as to be parallel to the surface of the dielectric substrate 5. By appropriately providing a reflector such as a reflector or a corner reflector, it is useful as an antenna element of an array antenna that requires a wireless zone in a single direction with a wide band.
[0028]
FIG. 13 is a diagram illustrating an example of an array antenna that uses the broadband antenna of the present embodiment as an antenna element.
As shown in FIG. 13, by arranging the wideband antenna shown in FIG. 12, the radiation aperture of the antenna can be easily widened, which is useful as an antenna element for an array antenna that requires a wide band and high gain.
[0029]
FIG. 14 is a diagram illustrating a schematic configuration of another example of the broadband antenna according to the present embodiment.
In the figure, reference numerals 22 and 23 denote L-shaped conductors having an L-shaped one end.
The broadband antenna shown in FIG. 14 is provided with L-shaped conductors (22, 23) so that parallel regions of the L-shaped conductors (22, 23) face each other, and the L-shaped conductors (22, 23). 23) is connected to the loop conductor 20 at the other end.
Also in the broadband antenna shown in FIG. 14, strong radiation can be performed in a direction perpendicular to the surface of the dielectric substrate 5.
In FIGS. 12 and 13, the dotted line indicates a line for supplying power to the power supply conductors (24, 25).
[0030]
[Embodiment 5]
FIG. 15 is a perspective view showing a schematic configuration of the wideband antenna according to the fifth embodiment of the present invention.
The broadband antenna of the present embodiment is such that the parallel region of the half-loop conductor 1 and the L-shaped conductor 2 ₁ is bent at a right angle in order to adjust the degree of bidirectional directivity. This is different from the first embodiment.
FIG. 16 is a graph showing the directivity characteristics of the electric field component on the XY plane in the coordinate system shown in FIG. 15, which is an example of the broadband antenna according to the present embodiment.
As can be seen from the graph of FIG. 16, according to the wideband antenna of the present embodiment, the maximum radiation direction of the directivity is unified, so that adjustment according to the scale and direction of the radio zone is possible.
Incidentally, in the antenna of the present embodiment, instead of bending the parallel region of the half-loop-shaped conductor 1 and the L-shaped conductor 2 ₁ at right angles, as shown in FIG. 17, the half-loop-shaped conductor 1 parallel region of the L-shaped conductor 2 ₁ may be formed in an arc shape.
[0031]
Although the invention made by the present inventor has been specifically described based on the above-described embodiment, the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the scope of the invention. Of course.
[0032]
【The invention's effect】
The effects obtained by the representative ones of the inventions disclosed in the present application will be briefly described as follows.
[0033]
(1) According to the present invention, one of the terminal portion regions of the second conductor is electromagnetically coupled to the terminal portion region of the first conductor or the feeding conductor, so that the second conductor is not fed. Since it is made to function as an element, the band characteristics can be made wider than before, thereby providing a wide band antenna having a low attitude and bidirectional directivity and wider than before. It becomes possible.
[0034]
(2) According to the present invention, since the low-profile, wide-band antenna having bidirectional directivity and the wide-band antenna line-symmetric with the wide-band antenna are formed on the dielectric substrate, Strong radiation can be performed in a direction perpendicular to the surface of the substrate, and this makes it possible to provide a wide-band antenna having high gain and bidirectional directivity and a wider bandwidth than before.
[Brief description of the drawings]
FIG. 1 is a perspective view showing a schematic configuration of a wideband antenna according to a first embodiment of the present invention.
FIG. 2 is a graph showing frequency characteristics of VSWR of an example of the wideband antenna according to the first embodiment;
FIG. 3 is a graph showing the directional characteristics of the electric field component on the XY plane when the frequency is 840 MHz, as an example of the wideband antenna according to the first embodiment.
FIG. 4 is a graph showing the directivity characteristics of the electric field component on the XY plane when the frequency is 920 MHz, as an example of the wideband antenna according to the first embodiment.
FIG. 5 is a graph showing the directivity characteristics of the electric field component on the XY plane when the frequency is 1000 MHz, as an example of the wideband antenna according to the first embodiment.
FIG. 6 is a schematic diagram showing another example of the wideband antenna according to the first embodiment.
FIG. 7 is a schematic diagram showing another example of the wideband antenna according to the first embodiment.
FIG. 8 is a schematic diagram showing another example of the ground conductor in the wideband antenna according to the first embodiment.
9 is a schematic diagram showing directivity characteristics in the XZ plane when the ground conductor shown in FIG. 8 is used as the ground conductor. FIG.
FIG. 10 is a perspective view showing a schematic configuration of a wideband antenna according to a second embodiment of the present invention.
FIG. 11 is a diagram showing a schematic configuration of a wideband antenna according to a third embodiment of the present invention.
FIG. 12 is a diagram showing a schematic configuration of a wideband antenna according to a fourth embodiment of the present invention.
FIG. 13 is a diagram showing an example of an array antenna using the wideband antenna according to the fourth embodiment of the present invention as an antenna element.
FIG. 14 is a diagram showing a schematic configuration of another example of the wideband antenna according to the fourth embodiment of the present invention.
FIG. 15 is a perspective view showing a schematic configuration of a wideband antenna according to a fifth embodiment of the present invention.
FIG. 16 is a graph showing the directivity characteristics of the electric field component on the XY plane of an example of the wideband antenna according to the fifth embodiment.
FIG. 17 is a perspective view showing a schematic configuration of another example of the broadband antenna according to the fifth embodiment of the present invention.
FIG. 18 is a perspective view showing a schematic configuration of a conventional half-loop antenna.
19 is a graph showing the directivity characteristics of the electric field component on the XY plane of an example of the half-loop antenna shown in FIG.
20 is a graph showing frequency characteristics of VSWR of an example of the half-loop antenna shown in FIG.
[Explanation of symbols]
1, 11,... Semi-loop conductor, 2 ₁ , 22, 23... L-shaped conductor, 2 ₂ , 24, 25 ... Feed conductor, 3, 3 a, 3 b, 12 ... Ground conductor, 4, 13. Feed point, 41 ... core conductor, 5 ... dielectric substrate, 6 ... coaxial plug, 7 ... balance - unbalance converter, 20 ... loop conductor.

Claims

A grounding conductor;
A dielectric substrate disposed on the ground conductor;
A parasitic element that is formed on one surface of the dielectric substrate and includes a second conductor whose both ends are electrically connected to the ground conductor;
Wherein formed on the opposite surface of the dielectric one surface of the substrate, connecting a first conductor having one end Ru is an open end, the one point spaced a predetermined distance from one end of the first conductor and the feeding point to possess the formed excitation element between the feeding conductor,
The other end portion of the first conductor is coupled to the first terminal portion region including one end portion of the second conductor or the second terminal portion region including the other end portion at a high frequency, and the grounding is performed. A broadband antenna electrically connected to a conductor ,
The feeding conductor is connected to a feeding conductor ,
The power supply conductor is provided at the end of the second terminal area or the first terminal area of the second conductor through at least a part of the projection area of the second conductor. wideband antenna, characterized in that it is extended to a point.

The first conductor includes a terminal portion region including the other end portion disposed substantially perpendicular to the ground conductor, and a parallel portion region including the one end portion disposed substantially parallel to the ground conductor. Configured,
Before Symbol feed conductor is disposed substantially perpendicular to the ground conductor,
Before Stories second conductor, the said first terminal region installed substantially perpendicular to the ground conductor, and the second terminal region installed substantially perpendicular to the ground conductor, the ground conductor The broadband antenna according to claim 1, wherein the broadband antenna is configured to be parallel to a parallel region.

The grounding conductor is formed in a corner shape having a first conductor or a second conductor as an apex angle, or an arc having an installation position of the first conductor or the second conductor outside the arc. The broadband antenna according to claim 1 or 2, characterized in that

A loop-shaped first conductor whose both ends are open ends, a first feeding conductor that connects a point that is a predetermined distance away from one end of the first conductor and a feeding point, and the first conductor An excitation element composed of a second feeding conductor that connects a feeding point to a point separated from the other end of the feeding point by a predetermined distance;
A broadband antenna having a parasitic element formed of a loop-shaped second conductor, a portion of which is installed substantially parallel to a portion of the first conductor;
The second conductor is the portion between the open ends of the first conductor in the second conductor is grounded,
A grounding conductor having a cut at one end and the other end connected to a grounded portion of the second conductor ;
A power supply circuit composed of a balanced-unbalanced conversion circuit,
The ground conductor constitutes a part of the balanced-unbalanced conversion circuit, and the parts divided by the notch are connected to the first and second feeding conductors, respectively. Wideband antenna.

A parasitic element composed of a loop-shaped third conductor;
A first conductor and a second conductor whose one end is an open end and whose other end is connected to the third conductor, a point separated from the one end of the first conductor by a predetermined distance, and a feeding point A broadband antenna having a first feeding conductor that connects to the first feeding conductor and an excitation element that includes a second feeding conductor that connects the feeding point to a point that is a predetermined distance away from one end of the second conductor. There,
The third conductor is grounded at a portion facing the open ends of the first conductor and the second conductor,
A part of said 3rd conductor is installed substantially parallel to a part of said 1st conductor and 2nd conductor, The wideband antenna characterized by the above-mentioned.