JP3828050B2

JP3828050B2 - Antenna array and wireless device

Info

Publication number: JP3828050B2
Application number: JP2002174293A
Authority: JP
Inventors: 根秀一関; 上康村; 舘紀章大; 村彰宏辻; 藤敬義伊; 上和弘井
Original assignee: Toshiba Corp
Current assignee: Toshiba Corp
Priority date: 2002-06-14
Filing date: 2002-06-14
Publication date: 2006-09-27
Anticipated expiration: 2022-06-14
Also published as: JP2004023369A

Description

【０００１】
【発明の属する技術分野】
複数のアンテナを有するアンテナアレーと、複数のアンテナのそれぞれに対応した複数の無線機を有する無線装置に関する。
【０００２】
【従来の技術】
近年、２ＧＨｚ近傍の周波数帯で動作する無線システムが数多く開発されている。例えば、２．４ＧＨｚ帯で動作する無線システムには無線ＬＡＮとBluetooth（登録商標）があるが、これらのシステムに対応した無線機が同じ端末内に実装される場合がある。
【０００３】
【発明が解決しようとする課題】
２つの無線機が同一周波数帯域で動作している場合には、アンテナを介して互いの送信電波による干渉が発生する。
【０００４】
上述した干渉を抑圧するには、アンテナを離して配置する必要があるが、端末の小型・薄型化に伴って、アンテナを離して配置するのがスペース的に困難になりつつある。
【０００５】
端末が小型・薄型化すると、アンテナは低姿勢になるが、低姿勢化したアンテナでは、アンテナ自身の放射だけでなく、近接する導体を介してアンテナ間結合が発生し、上述した干渉が起こりやすくなる。この種のアンテナ間結合が発生すると、アンテナ自身の放射だけでなく、アンテナが接続される地板からの放射も大きくなる。特に、２つのアンテナが同じ地板上に配置される場合、２つのアンテナは、地板を介して接続されるのと同じ状態になり、干渉が大きくなる。この種の送信電波の干渉が起きると、通信品質が低下してしまう。
【０００６】
本発明は、このような点に鑑みてなされたものであり、その目的は、送信電波の干渉を抑制可能なアンテナアレー及び無線装置を提供することにある。
【０００７】
【課題を解決するための手段】
上述した課題を解決するために、本発明の一態様によれば、地板上の第１給電点と、この第１給電点から前記地板に対して略垂直に延びる第１導体素子と、この第１導体素子の先端部から前記地板に略平行に延びる第２導体素子と、前記第１導体素子の先端部から前記第２導体素子の反対側に延び前記第２導体素子とは異なる長さをもつ第３導体素子と、を有し第１動作周波数で共振する第１アンテナと、前記地板上の第２給電点と、この第２給電点から前記地板に対して略垂直に延びる第４導体素子と、この第４導体素子の先端部から前記地板に略平行に延びる第５導体素子と、前記第４導体素子の先端部から前記第５導体素子の反対側に延び前記第５導体素子とは異なる長さをもつ第６導体素子と、を有し第２動作周波数で共振する第２アンテナと、を備え、前記第２及び第３導体素子の長さの和は、前記第１動作周波数の略半波長であり、前記第５及び第６導体素子の長さの和は、前記第２動作周波数の略半波長であり、前記第３導体素子は、前記第５導体素子に略平行かつ前記第１給電点および前記第２給電点の間に配置され、かつ前記第１動作周波数は前記第２動作周波数より低く、かつ前記第２導体素子は前記第３導体素子より短く、かつ前記第５導体素子は前記第６導体素子より短く、前記第５導体素子は前記第１給電点および前記第２給電点の間に配置されることを特徴とするアンテナアレーが提供される。
【０００９】
また、本発明の一態様によれば、地板上の第１給電点と、この第１給電点から前記地板に対して略垂直に延びる第１導体素子と、この第１導体素子の先端部から前記地板に略平行に延びる第２導体素子と、前記第１導体素子の先端部から前記第２導体素子の反対側に延び前記第２導体素子とは異なる長さをもつ第３導体素子と、を有し第１動作周波数で共振する第１アンテナと、前記地板上の第２給電点と、この第２給電点から前記地板に対して略垂直に延びる第４導体素子と、この第４導体素子の先端部から前記地板に略平行に延びる第５導体素子と、前記第４導体素子の先端部から前記第５導体素子の反対側に延び前記第５導体素子とは異なる長さをもつ第６導体素子と、を有し第２動作周波数で共振する第２アンテナと、を備え、前記第２及び第３導体素子の長さの和は、前記第１動作周波数の略半波長であり、前記第５及び第６導体素子の長さの和は、前記第２動作周波数の略半波長であり、前記第２導体素子は、前記第５導体素子に略平行かつ前記第１給電点および前記第２給電点の間に配置され、かつ前記第１動作周波数は前記第２動作周波数より低く、かつ前記第２導体素子は前記第３導体素子より短く、かつ前記第５導体素子は前記第６導体素子より短く、前記第５導体素子は前記第１給電点および前記第２給電点の間に配置されることを特徴とするアンテナアレーが提供される。
また、本発明の一態様によれば、地板上の第１給電点と、この第１給電点から前記地板に対して略垂直に延びる第１導体素子と、この第１導体素子の先端部から前記地板に略平行に延びる第２導体素子と、前記第１導体素子の先端部から前記第２導体素子の反対側に延び前記第２導体素子とは異なる長さをもつ第３導体素子と、を有し第１動作周波数で共振する第１アンテナと、前記地板上の第２給電点と、この第２給電点から前記地板に対して略垂直に延びる第４導体素子と、この第４導体素子の先端部から前記地板に略平行に延びる第５導体素子と、前記第４導体素子の先端部から前記第５導体素子の反対側に延び前記第５導体素子とは異なる長さをもつ第６導体素子と、を有し第２動作周波数で共振する第２アンテナと、を備え、前記第２及び第３導体素子の長さの和は、前記第１動作周波数の略半波長であり、前記第５及び第６導体素子の長さの和は、前記第２動作周波数の略半波長であり、前記第３導体素子は、前記第５導体素子に略平行かつ前記第１給電点および前記第２給電点の間に配置され、かつ前記第１動作周波数は前記第２動作周波数より低く、かつ前記第２導体素子は前記第３導体素子より短く、かつ前記第５導体素子は前記第６導体素子より短く、前記第６導体素子は前記第１給電点および前記第２給電点の間に配置されることを特徴とするアンテナアレーが提供される。
【００１０】
【発明の実施の形態】
以下、本発明に係るアンテナアレー及び無線装置について、図面を参照しながら具体的に説明する。
【００１１】
（第１の実施形態）
図１は本発明に係るアンテナアレーの第１の実施形態の概略的な配置図である。図１のアンテナアレーは、同一の地板１上に配置される第１及び第２アンテナ２，３を備えている。図１では省略しているが、第１アンテナ２は給電点４を通して第１無線機に接続され、第２アンテナ３は給電点７を通して第２無線機に接続されている。
【００１２】
第１アンテナ２は、地板１上の第１給電点４と、この第１給電点４から地板１に対して略垂直に延びる第１導体素子５と、この第１導体素子５の先端部から地板１に略平行に延びる第２導体素子６とを有する。第１導体素子５及び第２導体素子６の長さの和は、第１アンテナ２の動作周波数の略１／４波長に設定されている。
【００１３】
第２アンテナ３は、地板１上の第２給電点７と、この第２給電点７から地板１に対して略垂直に延びる第３導体素子８と、この第３導体素子８の先端部から地板１に略平行に延びる第４導体素子９とを有する。第３導体素子８及び第４導体素子９の長さの和は、第２アンテナ３の動作周波数の略１／４波長に設定されている。
【００１４】
第２導体素子６と第４導体素子９は同じ向きに配置されている。すなわち、第４導体素子９の先端部は第１及び第２給電点４，７の間に配置され、第２導体素子６の先端部は第１給電点４を基準として第２給電点７の反対側に配置されている。なお、図２（ａ）に示すように、第２アンテナ３を第１アンテナ２の延長線上から少しずらして配置してもよい。あるいは、図２（ｂ）に示すように、第２導体素子６の先端部を第１及び第２給電点４，７の間に配置し、第４導体素子９の先端部を第２給電点７を基準として第１給電点４の反対側に配置してもよい。
【００１５】
図１の第１及び第２アンテナ２，３において、インピーダンス整合が取れない場合には、第１及び第２給電点４，７の近傍に整合回路を設けるか、あるいは逆Fアンテナのように第１及び第３導体素子８を地板１に短絡させる配線を接続してもよい。これにより、インピーダンスが変化して整合を取ることができる。
【００１６】
図３は第１及び第２アンテナ２，３の整合特性と結合特性を示す図である。図３では、第１及び第２アンテナ２，３の距離を一定にした状態で、これらアンテナの向きを変えたモデルＡ，Ｂ，Ｃの整合特性と結合特性のシミュレーションによる計算結果を示している。
【００１７】
モデルＡは図１のように配置した場合であり、モデルＢは第１及び第２アンテナ２，３を逆向きに配置した場合、モデルＣは第１及び第２アンテナ２，３を対向配置した場合である。
【００１８】
図３からわかるように、第１及び第２アンテナ２，３の整合が取れている場所で、モデルＡの結合量を他のモデルＢ，Ｃと比較すると、１〜２ｄＢ程度アンテナ間結合が減る。
【００１９】
図４はモデルＡ，Ｂ，Ｃの第１及び第２アンテナ２，３上の電流分布を示す模式図である。第１及び第２アンテナ２，３は、１／４波長の長さを有するため、電流は給電点を最大とする正弦波状に分布する。
【００２０】
一般に、アンテナ間結合は、アンテナ上の電流分布の大きい部分が近接することで強くなると考えられている。第１及び第２アンテナ２，３間の距離はモデルＣが最も離れており、モデルＢが最も近接しているため、直感的にはモデルＣが最もアンテナ間結合が少ないように思える。ところが実際には、モデルＣの結合量が一番大きくなり、モデルＢはモデルＣよりも結合量が小さくなる。このような現象が起きる理由は、地板１に流れる電流による結合が生じるためである。
【００２１】
また、図５は地板１上の電流分布を示す模式図である。図５からわかるように、地板１上の電流には、地板１と平行に配置された第２及び第４導体素子６，９によって誘起される電流が加わる。このため、第２及び第４導体素子６，９と同じ向きに強い電流分布が生じ、その結果、アンテナ間結合が生じる。第２及び第４導体素子６，９上の電流分布は空間を介して結合するが、地板１上の電流は地板１を介して結合する。
【００２２】
この種のアンテナ間結合は、アンテナが地板１と平行に配置された平板状の場合に顕著に発生する。また、地板１上の電流だけに着目すれば、モデルＢのように第１及び第２アンテナ２，３を互いに逆方向に配置することでアンテナ間結合の削減が期待できる。ところが、この場合、第１及び第２アンテナ２，３上の電流が最大になる位置が近接するため、その影響を受けてアンテナ間結合が強くなってしまう。
【００２３】
一方、本実施形態が推奨するモデルＡでは、まずアンテナ上の電流の最大値がモデルＢより離れている。また地板１上の電流に関しては、片側のみが他方のアンテナ素子の方向に向いており、モデルＣのように両方が向き合うよりも良好な構成になる。以上のことから、本実施形態のアンテナアレーでは、他のアンテナアレーの構成よりもアンテナ間結合を小さくすることができる。
【００２４】
このように、第１の実施形態では、第１アンテナ２の第２導体素子６と第２アンテナ３の第４導体素子９とを略同一方向に配置するため、アンテナ間結合を抑制できるとともに、地板１上の結合も抑制でき、電波の干渉が起きにくくなり、アンテナの結合特性がよくなる。
【００２５】
（第２の実施形態）
第２の実施形態は、地板１の辺縁部に第１及び第２アンテナ２，３を配置するものである。
【００２６】
図６は本発明に係るアンテナアレーの第２の実施形態の概略的な配置図である。図示のように、同一の有限地板１の辺縁部に第１アンテナ２の第１給電点４と第２アンテナ３の第２給電点７とが配置され、第１アンテナ２の第２導体素子６と第２アンテナ３の第４導体素子９は辺縁部に略平行に同じ向きに配置されている。
【００２７】
一般に、導体板では、辺縁部の電流分布が大きいため、アンテナを辺縁部に配置すると、より大きな電流が辺縁部に分布することになる。したがって、図６のように配置した場合、アンテナ間結合がより大きくなる。その理由は、第１及び第２アンテナ２，３が辺縁部に配置されると、辺縁部への電流の漏洩が多くなるためである。したがって、図６に示すように、有限地板１の辺縁部に第１及び第２アンテナ２，３を略平行かつ同じ向きに配置すると、アンテナ間結合をよりいっそう抑制することができる。
【００２８】
図７は図６の変形例であり、有限地板１の隣接する２辺の一方に第１アンテナ２を配置し、他方に第２アンテナ３を配置する例を示している。この場合は、各アンテナが地板１の辺縁部に平行になるように配置し、かつ第２導体素子６及び第４導体素子９のいずれか一方の先端部を第１及び第２給電点４，７の間に配置し、他方の先端部を、第１給電点４を基準として第２給電点７の反対側に配置するか、または第２給電点７を基準として第１給電点４の反対側に配置すればよい。
【００２９】
このように、第２の実施形態では、地板１の辺縁部に第１及び第２アンテナ２，３を配置するため、アンテナ間結合の抑制効果を高めることができる。
【００３０】
（第３の実施形態）
第３の実施形態は、地板１の辺縁部に補助地板を配置し、この補助地板上に第１及び第２アンテナ２，３を配置するものである。
【００３１】
図８は本発明に係るアンテナアレーの第３の実施形態の概略的な配置図である。図示のように、地板１の辺縁部に配置された補助地板１０と、この補助地板１０上の辺縁部に配置された第１及び第２アンテナ２，３とを備えている。
【００３２】
地板１と補助地板１０は、容量性結合で結ばれるため、高周波的には図７に示した第２の実施形態と同様の構成になる。したがって、第１アンテナ２の第１導体素子５と第２アンテナ３の第２導体素子６を辺縁部に略平行かつ同じ方向に配置することで、第２の実施形態と同様に、アンテナ間結合をより効率的に抑制できる。図８の場合の容量結合は、第１及び第２アンテナ２，３を直接地板１に接続した場合よりも弱いため、アンテナ間結合が第２の実施形態よりも小さくなる。
【００３３】
（第４の実施形態）
上述した第１〜第３の実施形態ではＬ字型のアンテナを用いる例を説明したが、以下に説明する第４〜第１０の実施形態ではＴ字型のアンテナを用いる。
【００３４】
図９は本発明に係るアンテナアレイの第４の実施形態の概略的な配置図である。図９のアンテナアレイは、地板１上に配置されたＴ字型の第１及び第２アンテナ２１，２２を備えている。第１及び第２アンテナ２１，２２は、略同一線上に配置されている。なお、図１０に示すように、第１及び第２アンテナ２１，２２を少しずらして配置してもよい。この場合、第１及び第２アンテナ２１，２２が互いに重なり合わないように平行に配置するのが望ましい。
【００３５】
第１アンテナ２１は、地板１上の第１給電点２３と、この第１給電点２３から地板１に対して略垂直に延びる第１導体素子２４と、この第１導体素子２４の先端部から地板１に略平行に延びる第２導体素子２５と、第１導体素子２４の先端部から第２導体素子２５の反対側に延びる第３導体素子２６と、を有し、第１動作周波数で共振する。
【００３６】
第２アンテナ２２は、地板１上の第２給電点２７と、この第２給電点２７から地板１に対して略垂直に延びる第４導体素子２８と、この第４導体素子２８の先端部から地板１に略平行に延びる第５導体素子２９と、第４導体素子２８の先端部から第５導体素子２９の反対側に延びる第６導体素子３０と、を有し、第２動作周波数で共振する。
【００３７】
第２及び第３導体素子２５，２６の長さの和は、第１動作周波数の略半波長であり、第５及び第６導体素子２９，３０の長さの和は、第２動作周波数の略半波長である。
【００３８】
第１アンテナ２１の第１及び第２導体素子２５，２６の長さの比を調整することで、第１アンテナ２１を第１動作周波数で給電線のインピーダンスである５０Ωに整合させることができる。同様に、第２アンテナ２２の第５及び第６導体素子２９，３０の長さの比を調整することで、第２アンテナ２２を第２動作周波数で給電線のインピーダンスである５０Ωに整合させることができる。
【００３９】
図１１及び図１２は第１及び第２アンテナ２１，２２の構成例を示す図であり、図１１は１．９ＧHｚで５０Ωになるように構成した例、図１２は２．１ＧＨｚで５０Ωになるように構成した例を示している。
【００４０】
図１１の場合、第１導体素子２４の長さは６．５mm、第２導体素子２５の長さは３１．５mm、第３導体素子２６の長さは３５．６mmで、これら導体素子の径φは０．８mmである。また、図１２の場合、第１導体素子２４の長さは７mm、第２導体素子２５の長さは３４mm、第３導体素子２６の長さは３８．５mmで、これら導体素子の径φは０．８mmである。
【００４１】
図１０のようなＴ字型アンテナは、図１のようなＬ字型アンテナと比べて、地板１に多くの電流が流れないという特徴を有する。
【００４２】
図１３はＴ字型アンテナの放射パターンを示す図である。この図からわかるように、Ｔ字型アンテナの長手方向には、放射パターンのヌルが向けられることになる。したがって、図１０のように略同一線上に第１及び第２アンテナ２１，２２を配置すると、一方のアンテナには他方のアンテナのヌルが向けられるので、アンテナ間結合を十分に抑制できる。
【００４３】
このように、第４の実施形態では、Ｔ字型アンテナを略同一線上に配置するため、アンテナ間結合が起きにくくなり、電波の干渉が起きにくくなる。
【００４４】
（第５の実施形態）
第５の実施形態は、地板１の辺縁部に２つのＴ字型アンテナを配置するものである。
【００４５】
図１４は本発明に係るアンテナアレーの第５の実施形態の概略的な配置図である。図１０と同じ形状の第１及び第２アンテナ２１，２２が有限地板１の辺縁部に配置されている。より具体的には、第１及び第２アンテナ２１，２２の第２、第３、第５及び第６導体素子２５，２６，２９，３０は辺縁部に略平行に配置されている。
【００４６】
第１及び第２アンテナ２１，２２を有限地板１の辺縁部に配置すると、有限地板１上に流れるイメージ電流が不完全になり、有限地板１からの放射が減少する。このイメージ電流は、アンテナ上の電流と逆相になるため、アンテナからの放射電波を打ち消しているが、上記のように不完全となることで、アンテナからの放射の打ち消しが抑圧され、よりアンテナからの放射が大きくなる。
【００４７】
また、図１４の第１及び第２アンテナ２１，２２の各導体素子方向には、図１３と同様にヌルが向けられるので、第１及び第２アンテナ２１，２２を有限地板１の辺縁部に配置しても、アンテナ間結合の劣化はあまり大きくならない。
【００４８】
このように、第５の実施形態では、第１及び第２アンテナ２１，２２を有限地板１の辺縁部に配置するため、有限地板１からの放射を減少でき、アンテナの放射特性を向上できる。
【００４９】
（第６の実施形態）
第６の実施形態は、有限地板１の辺縁部に補助地板１０を配置し、この補助地板１０の辺縁部に２つのＴ字型アンテナを配置するものである。
【００５０】
図１５は本発明に係るアンテナアレーの第６の実施形態の概略的な配置図である。図１５のアンテナアレーは、有限地板１の辺縁部に配置された補助地板１０と、これら補助地板１０の辺縁部に配置された図１０と同じ形状の第１及び第２アンテナ２１，２２とを備えている。第１及び第２アンテナ２１，２２の第２、第３、第５及び第６導体素子２５，２６，２９，３０は補助地板１０の辺縁部に略平行に配置されている。
【００５１】
有限地板１と補助地板１０は容量性結合で結びつくため、高周波的には図１４と同じ構成になる。また、補助地板１０を設けたことにより、有限地板１を介した結合が図１４よりも弱まるため、図１４よりもアンテナ間結合を弱めることができる。
【００５２】
このように、第６の実施形態では、有限地板１の周縁部に補助地板１０を設け、この補助地板１０の周縁部に第１及び第２アンテナ２１，２２を配置するため、アンテナ間結合を弱めることができ、電波の干渉が起きにくくなる。
【００５３】
（第７の実施形態）
第５、６の実施形態では省略したが、本アンテナにおいても、導体素子に生じた電流によって結合が生じる。図１６は図１０に示したＴ字型アンテナの電流分布を周波数ごとに模式的に示した図である。第１アンテナ２１は、第２導体素子２５を第３導体素子２６よりも長くしており、共振周波数はｆ１である。この場合、第１アンテナ２１の電流分布は、共振周波数ｆ１より低い周波数と高い周波数で大きく変化する。
【００５４】
図１６に示すように、共振周波数ｆ１より低い周波数では、第２導体素子２５に大きな電流分布が発生し、共振周波数ｆ１より高い周波数では、第３導体素子２６に大きな電流分布が発生する。共振周波数ｆ１より低い周波数でも、高い周波数でも、第１の実施形態で説明したＬ字型アンテナと同様に動作する。すなわち、Ｔ字型アンテナは、等価的に、周波数が変化するに従って向きが異なるＬ字型アンテナとして機能する。このため、Ｌ字の向きが固定の第１の実施形態とは別個の対策が必要になる。
【００５５】
また、Ｔ字型アンテナは、給電点が第２及び第３導体素子２５，２６の略中央に位置しているため、第２及び第３導体素子２５，２６の向きを変えても、給電点の位置は変化しない。したがって、Ｌ字型アンテナでは、Ｌ字の向きを変えることで給電点が移動するため電流の最大位置が大きく変化し、それに応じてアンテナ間結合の強さも変化するが、Ｔ字型ではほとんど変化しない。このため、Ｔ字型アンテナでは、第２及び第３導体素子２５，２６のうち電流分布の大きい導体素子が他方のアンテナの方向を向かないように配置するだけでよい。
【００５６】
図１７は本発明に係るアンテナアレーの第７の実施形態の概略的な配置図である。図１７では、第１アンテナ２１の動作周波数（第１動作周波数）を第２アンテナ２２の動作周波数（第２動作周波数）よりも低くしている。したがって、第１アンテナ２１の第２及び第３導体素子２５，２６の長さの和よりも、第２アンテナ２２の第５及び第６導体素子２９，３０の長さの和を短くしている。また、第５導体素子２９を第４導体素子２８よりも長くし、第３導体素子２６を第２導体素子２５よりも長くしている。このように構成することで、上記の周波数条件において、他のアンテナ構成よりもアンテナ間結合を小さくできる。
【００５７】
図１８は、第１動作周波数ｆ＃１が第２動作周波数ｆ＃２よりも低い場合に、第１及び第２アンテナ２１，２２（図は、地板１の法線方向からアンテナを眺めている。またアンテナ２１，２２は図中＃１、＃２で表示）が取り得る地板１への実装方法のすべてを示したものである。第１動作周波数と第２動作周波数は周波数が異なるため、第１及び第２アンテナ２１，２２の大きさは異なったものになる。すなわち、第２導体素子２５は第３導体素子２６と異なった長さになり、第４導体素子２８は第５導体素子２９と異なった長さになる。
【００５８】
第１及び第２アンテナ２１，２２の配置法の組み合わせとして、図１８のモデルＡ〜Ｄの４種類がある。モデルＡは、図１７と同様に、第２導体素子２５の長さ＜第３導体素子２６の長さで、かつ第５導体素子２９の長さ＜第６導体素子３０の長さである。モデルＢは、第２導体素子２５の長さ＜第３導体素子２６の長さで、かつ第５導体素子２９の長さ＞第６導体素子３０の長さである。モデルＣは、第２導体素子２５の長さ＞第３導体素子２６の長さで、かつ第５導体素子２９の長さ＜第６導体素子３０の長さである。モデルＤは、第２導体素子２５の長さ＞第３導体素子２６の長さで、かつ第５導体素子２９の長さ＞第６導体素子３０の長さである。
【００５９】
図１８において、「大」と記載された導体素子は、その周波数帯での電流分布が大きいことを示している。図１８では、モデルＡ〜Ｄのそれぞれについて、第１動作周波数（共振周波数）ｆ＃１と第２動作周波数（共振周波数）ｆ＃２の前後における電流分布を把握できる。
【００６０】
図１８からわかるように、第１アンテナ２１の電流分布の大きい場所と第２アンテナ２２の電流分布の大きい場所とが最も離れているのは、モデルＡである。したがって、モデルＡのように第１及び第２アンテナ２１，２２を配置すれば、電流分布が大きな部分が向き合い最近接状態となるおそれがなくなる。
【００６１】
図１９は、モデルＡ〜Ｄのアンテナアレーを用いて、給電点間の距離を１００mmとしたときのアンテナ間の最大結合量を示している。この図からわかるように、周波数ｆ＃１〜ｆ＃２の帯域で、モデルＡが他のモデルに比べてアンテナ間結合が弱くなる。
【００６２】
このように、第７の実施形態では、電流分布の大きな部分が向き合い近接しないように第１及び第２アンテナ２１，２２を配置するため、電波の干渉が起きにくくなる。
【００６３】
（第８の実施形態）
第８の実施形態は、第１アンテナ２１が送信アンテナで、第２アンテナ２２が受信アンテナであり、第１アンテナ２１の動作周波数（第１動作周波数）ｆ＃１が第２アンテナ２２の動作周波数（第２動作周波数）ｆ＃２より低い場合のアンテナ構成である。
【００６４】
このような場合、送信アンテナから受信アンテナへの回り込みが最大の問題になる。したがって、送信周波数でのアンテナ間結合が小さくなるようにアンテナアレーを構成する必要がある。
【００６５】
そこで、第８の実施形態では、第２アンテナ２２の第５導体素子２９を第６導体素子３０よりも短くする。
【００６６】
図１８において、モデルＡまたはＣを選択することで、第１動作周波数ｆ＃１近傍でのアンテナ間結合を小さくできることがわかる。モデルＡまたはＣでは、第５導体素子２９が第６導体素子３０より短いため、第１アンテナ２１の動作周波数ｆ＃１にてアンテナ間結合を抑制することができる。
【００６７】
このように、第８の実施形態では、送信周波数が受信周波数よりも低い場合に、第２アンテナ２２の第５導体素子２９を第６導体素子３０より短くするため、送信周波数ｆ＃１でのアンテナ間結合を抑制でき、送信アンテナから受信アンテナへの回り込みを回避できる。
【００６８】
（第９の実施形態）
第９の実施形態では、送信周波数が受信周波数よりも高い場合に、送信アンテナから受信アンテナへの回り込みを回避するものである。
【００６９】
図１８において、周波数ｆが、ｆ＃２＜ｆ＜ｆ＃１か、ｆ＃２＜ｆの場合、モデルＡ，Ｂのいずれでも、第１アンテナ２１の第２導体素子２５を第３導体素子２６よりも短くしている。このような構成にすることで、送信周波数であるｆ＃２近傍にて、アンテナ間結合を抑制できる。
【００７０】
このように、送信周波数が受信周波数よりも高い場合に、第１アンテナ２１の第２導体素子２５を第３導体素子２６よりも短くすることで、送信周波数ｆ＃２でのアンテナ間結合を抑制でき、送信アンテナから受信アンテナへの回り込みを回避できる。
【００７１】
（第１０の実施形態）
第１０の実施形態では、第１アンテナ２１の動作周波数（第１動作周波数）ｆ＃１と第２アンテナ２２の動作周波数（第２動作周波数）ｆ＃２を略同一の場合、図１８のモデルＡまたはモデルＤではいずれも、第１及び第２アンテナ２１，２２の導体素子の向きが同じである。より具体的には、第２導体素子２５と第５導体素子２９が同じ長さで、かつ第３導体素子２６と第６導体素子３０が同じ長さにする。
【００７２】
このように、送信周波数と受信周波数がほぼ同一の場合には、第１及び第２アンテナ２１，２２をほぼ同じ向きにし、第２導体素子２５と第５導体素子２９を同じ長さにし、かつ第３導体素子２６と第６導体素子３０を同じ長さにすることで、アンテナ間結合を低減できる。
【００７３】
なお、本特許の説明において、導体素子はすべて直線状の素子として説明したが、図２０に示すように素子が変形していても効果は同じである。図２０に示すアンテナでは、地板に略平行な導体素子がヘリカル型とメアンダ型に変形されている。ヘリカル型では、ヘリカル３１の中心軸が地板に略平行となっておりこの方向が直線状素子の向きと等価である。またメアンダ型では、メアンダ素子３２が、地板に垂直な素子と接続されているあたりの部分の向きが直線状素子の向きと等価となる。
【００７４】
【発明の効果】
以上詳細に説明したように、本発明によれば、第１及び第２アンテナ２１，２２の向きを調整することにより、アンテナ間結合を減らして電波の干渉を防止できる。したがって、同一の無線装置内に複数の無線機用のアンテナを配置しても、互いに干渉し合うことなく、無線通信を行うことができる。
【図面の簡単な説明】
【図１】本発明に係るアンテナアレーの第１の実施形態の概略的な配置図。
【図２】図１の変形例を示す配置図。
【図３】第１及び第２アンテナ２，３の整合特性と結合特性を示す図。
【図４】モデルＡ，Ｂ，Ｃの第１及び第２アンテナ２，３上の電流分布を示す模式図。
【図５】地板１上の電流分布を示す模式図。
【図６】本発明に係るアンテナアレーの第２の実施形態の概略的な配置図。
【図７】図６の変形例であり、有限地板１の隣接する２辺の一方に第１アンテナ２を配置し、他方に第２アンテナ３を配置する例を示す図。
【図８】本発明に係るアンテナアレーの第３の実施形態の概略的な配置図。
【図９】本発明に係るアンテナアレイの第４の実施形態の概略的な配置図。
【図１０】図９の変形例を示す配置図。
【図１１】第１及び第２アンテナ２１，２２の構成例を示す図。
【図１２】第１及び第２アンテナ２１，２２の構成例を示す図。
【図１３】Ｔ字型アンテナの放射パターンを示す図。
【図１４】本発明に係るアンテナアレーの第５の実施形態の概略的な配置図。
【図１５】本発明に係るアンテナアレーの第６の実施形態の概略的な配置図。
【図１６】図１０に示したＴ字型アンテナの電流分布を周波数ごとに模式的に示した図。
【図１７】本発明に係るアンテナアレーの第７の実施形態の概略的な配置図。
【図１８】第１動作周波数ｆ＃１が第２動作周波数ｆ＃２よりも低い場合に、第１及び第２アンテナ２１，２２が取り得る地板１への実装方法のすべてを示した図。
【図１９】モデルＡ〜Ｄのアンテナアレーを用いて、給電点間の距離を１００mmとしたときのアンテナ間の最大結合量を示す図。
【図２０】導体素子がヘリカル型とメアンダ型に変形されている場合のアンテナアレーの形状を示す図。
【符号の説明】
１地板
２第１アンテナ
３第２アンテナ
４第１給電点
５第１導体素子
６第２導体素子
７第２給電点
８第３導体素子
９第４導体素子
１０補助地板
２１第１アンテナ
２２第２アンテナ
２３第１給電点
２４第１導体素子
２５第２導体素子
２６第３導体素子
２７第２給電点
２８第４導体素子
２９第５導体素子
３０第６導体素子[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an antenna array having a plurality of antennas and a radio apparatus having a plurality of radios corresponding to each of the plurality of antennas.
[0002]
[Prior art]
In recent years, many wireless systems that operate in a frequency band near 2 GHz have been developed. For example, wireless systems operating in the 2.4 GHz band include wireless LAN and Bluetooth (registered trademark), but wireless devices corresponding to these systems may be mounted in the same terminal.
[0003]
[Problems to be solved by the invention]
When two wireless devices are operating in the same frequency band, interference occurs due to the transmission radio waves via the antenna.
[0004]
In order to suppress the above-described interference, it is necessary to arrange the antennas apart from each other. However, as the terminals become smaller and thinner, it is becoming difficult to arrange the antennas apart.
[0005]
When the terminal is reduced in size and thickness, the antenna is lowered, but in the antenna lowered, not only radiation of the antenna itself but also coupling between the antennas occurs through a nearby conductor, and the above-described interference is likely to occur. Become. When this type of inter-antenna coupling occurs, not only the radiation of the antenna itself but also the radiation from the ground plane to which the antenna is connected increases. In particular, when two antennas are arranged on the same ground plane, the two antennas are in the same state as being connected via the ground plane, and interference increases. When this type of transmission radio wave interference occurs, communication quality deteriorates.
[0006]
The present invention has been made in view of such a point, and an object thereof is to provide an antenna array and a radio apparatus capable of suppressing interference of transmission radio waves.
[0007]
[Means for Solving the Problems]
In order to solve the above-described problem, according to one aspect of the present invention, a first feeding point on a ground plane, a first conductor element extending substantially perpendicularly to the ground plane from the first feeding point, A second conductor element extending substantially parallel to the ground plane from the tip of one conductor element, and extending from the tip of the first conductor element to the opposite side of the second conductor element and having a different length from the second conductor element. A third antenna having a first conductor that resonates at a first operating frequency, a second feeding point on the ground plane, and a fourth conductor extending substantially perpendicularly to the ground plane from the second feeding point. An element, a fifth conductor element extending substantially parallel to the ground plane from the tip of the fourth conductor element, and the fifth conductor element extending from the tip of the fourth conductor element to the opposite side of the fifth conductor element; Has a sixth conductor element having a different length, and has a second resonance frequency at a second operating frequency. A sum of the lengths of the second and third conductor elements is approximately half a wavelength of the first operating frequency, and a sum of the lengths of the fifth and sixth conductor elements is the first The third conductor element is substantially parallel to the fifth conductor element and disposed between the first feeding point and the second feeding point, and the first operating frequency is Lower than the second operating frequency, the second conductor element is shorter than the third conductor element, the fifth conductor element is shorter than the sixth conductor element, and the fifth conductor element is the first feeding point and An antenna array is provided that is disposed between the second feeding points.
[0009]
Moreover, according to one aspect of the present invention, the first feeding point on the ground plane, the first conductive element extending substantially perpendicularly to the ground plane from the first feeding point, and the tip of the first conductive element A second conductor element extending substantially parallel to the ground plane; a third conductor element extending from the tip of the first conductor element to the opposite side of the second conductor element and having a length different from that of the second conductor element; A first antenna that resonates at a first operating frequency, a second feed point on the ground plane, a fourth conductor element extending from the second feed point substantially perpendicular to the ground plane, and the fourth conductor A fifth conductor element extending substantially parallel to the ground plane from the tip of the element; and a fifth conductor element extending from the tip of the fourth conductor element to the opposite side of the fifth conductor element and having a length different from that of the fifth conductor element. A second antenna having a six-conductor element and resonating at a second operating frequency, The sum of the lengths of the second and third conductor elements is approximately half the wavelength of the first operating frequency, and the sum of the lengths of the fifth and sixth conductor elements is approximately the half wavelength of the second operating frequency. The second conductor element is substantially parallel to the fifth conductor element and disposed between the first feeding point and the second feeding point, and the first operating frequency is lower than the second operating frequency; And the second conductor element is shorter than the third conductor element, the fifth conductor element is shorter than the sixth conductor element, and the fifth conductor element is located between the first feeding point and the second feeding point. An antenna array is provided that is arranged.
Moreover, according to one aspect of the present invention, the first feeding point on the ground plane, the first conductive element extending substantially perpendicularly to the ground plane from the first feeding point, and the tip of the first conductive element A second conductor element extending substantially parallel to the ground plane; a third conductor element extending from the tip of the first conductor element to the opposite side of the second conductor element and having a length different from that of the second conductor element; A first antenna that resonates at a first operating frequency, a second feed point on the ground plane, a fourth conductor element extending from the second feed point substantially perpendicular to the ground plane, and the fourth conductor A fifth conductor element extending substantially parallel to the ground plane from the tip of the element; and a fifth conductor element extending from the tip of the fourth conductor element to the opposite side of the fifth conductor element and having a length different from that of the fifth conductor element. A second antenna having a six-conductor element and resonating at a second operating frequency, The sum of the lengths of the second and third conductor elements is approximately half the wavelength of the first operating frequency, and the sum of the lengths of the fifth and sixth conductor elements is approximately the half wavelength of the second operating frequency. The third conductor element is substantially parallel to the fifth conductor element and disposed between the first feeding point and the second feeding point, and the first operating frequency is lower than the second operating frequency; And the second conductor element is shorter than the third conductor element, the fifth conductor element is shorter than the sixth conductor element, and the sixth conductor element is located between the first feeding point and the second feeding point. An antenna array is provided that is arranged.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an antenna array and a radio apparatus according to the present invention will be specifically described with reference to the drawings.
[0011]
(First embodiment)
FIG. 1 is a schematic layout diagram of a first embodiment of an antenna array according to the present invention. The antenna array shown in FIG. 1 includes first and second antennas 2 and 3 disposed on the same ground plane 1. Although omitted in FIG. 1, the first antenna 2 is connected to the first radio through the feed point 4, and the second antenna 3 is connected to the second radio through the feed point 7.
[0012]
The first antenna 2 includes a first feeding point 4 on the ground plane 1, a first conductor element 5 extending substantially perpendicular to the ground plane 1 from the first feeding point 4, and a tip portion of the first conductor element 5. And a second conductor element 6 extending substantially parallel to the ground plane 1. The sum of the lengths of the first conductor element 5 and the second conductor element 6 is set to approximately ¼ wavelength of the operating frequency of the first antenna 2.
[0013]
The second antenna 3 includes a second feed point 7 on the ground plane 1, a third conductor element 8 extending substantially perpendicularly to the ground plane 1 from the second feed point 7, and a tip end portion of the third conductor element 8. And a fourth conductor element 9 extending substantially parallel to the ground plane 1. The sum of the lengths of the third conductor element 8 and the fourth conductor element 9 is set to approximately ¼ wavelength of the operating frequency of the second antenna 3.
[0014]
The second conductor element 6 and the fourth conductor element 9 are arranged in the same direction. That is, the tip of the fourth conductor element 9 is disposed between the first and second feeding points 4 and 7, and the tip of the second conductor element 6 is located at the second feeding point 7 with respect to the first feeding point 4. Located on the opposite side. Note that, as shown in FIG. 2A, the second antenna 3 may be arranged slightly shifted from the extension line of the first antenna 2. Alternatively, as shown in FIG. 2B, the tip of the second conductor element 6 is disposed between the first and second feeding points 4 and 7, and the tip of the fourth conductor element 9 is placed at the second feeding point. You may arrange | position on the opposite side of the 1st feeding point 4 on the basis of 7.
[0015]
When impedance matching cannot be achieved in the first and second antennas 2 and 3 of FIG. 1, a matching circuit is provided in the vicinity of the first and second feeding points 4 and 7, or the first and second antennas 2 and 3 can You may connect the wiring which short-circuits the 1st and 3rd conductor element 8 to the ground plane 1. FIG. Thereby, impedance can be changed and matching can be achieved.
[0016]
FIG. 3 is a diagram showing matching characteristics and coupling characteristics of the first and second antennas 2 and 3. FIG. 3 shows calculation results by simulation of matching characteristics and coupling characteristics of models A, B, and C in which the directions of the antennas are changed with the distance between the first and second antennas 2 and 3 being constant. .
[0017]
The model A is a case where the first and second antennas 2 and 3 are arranged in the reverse direction, and the model C is the case where the first and second antennas 2 and 3 are arranged opposite to each other. Is the case.
[0018]
As can be seen from FIG. 3, when the first and second antennas 2 and 3 are matched, the coupling amount of the model A is reduced by about 1 to 2 dB when compared with the other models B and C. .
[0019]
FIG. 4 is a schematic diagram showing the current distribution on the first and second antennas 2 and 3 of the models A, B and C. Since the first and second antennas 2 and 3 have a length of ¼ wavelength, the current is distributed in a sine wave shape that maximizes the feeding point.
[0020]
In general, it is considered that coupling between antennas becomes stronger when a portion with a large current distribution on the antenna comes close. Since the model C is the farthest distance between the first and second antennas 2 and 3 and the model B is the closest, it seems intuitively that the model C has the least inter-antenna coupling. However, in practice, the coupling amount of the model C is the largest, and the coupling amount of the model B is smaller than that of the model C. The reason why such a phenomenon occurs is that coupling due to the current flowing through the ground plane 1 occurs.
[0021]
FIG. 5 is a schematic diagram showing a current distribution on the ground plane 1. As can be seen from FIG. 5, a current induced by the second and fourth conductor elements 6 and 9 arranged in parallel with the ground plane 1 is added to the current on the ground plane 1. For this reason, a strong current distribution occurs in the same direction as the second and fourth conductor elements 6 and 9, and as a result, coupling between antennas occurs. The current distributions on the second and fourth conductor elements 6 and 9 are coupled through space, but the current on the ground plane 1 is coupled through the ground plane 1.
[0022]
This type of inter-antenna coupling occurs remarkably when the antenna is a flat plate arranged parallel to the ground plane 1. If attention is paid only to the current on the ground plane 1, reduction of coupling between antennas can be expected by arranging the first and second antennas 2 and 3 in opposite directions as in the model B. However, in this case, since the positions where the currents on the first and second antennas 2 and 3 are maximized are close to each other, the coupling between the antennas becomes strong under the influence.
[0023]
On the other hand, in the model A recommended by the present embodiment, the maximum value of the current on the antenna is first separated from the model B. As for the current on the ground plane 1, only one side is directed toward the other antenna element, which is a better configuration than both facing each other as in the model C. From the above, in the antenna array of the present embodiment, the inter-antenna coupling can be made smaller than in other antenna array configurations.
[0024]
Thus, in the first embodiment, since the second conductor element 6 of the first antenna 2 and the fourth conductor element 9 of the second antenna 3 are arranged in substantially the same direction, the coupling between the antennas can be suppressed, Coupling on the ground plane 1 can also be suppressed, radio wave interference is less likely to occur, and the antenna coupling characteristics are improved.
[0025]
(Second Embodiment)
In the second embodiment, the first and second antennas 2 and 3 are arranged on the edge portion of the ground plane 1.
[0026]
FIG. 6 is a schematic layout of a second embodiment of the antenna array according to the present invention. As shown in the drawing, the first feeding point 4 of the first antenna 2 and the second feeding point 7 of the second antenna 3 are arranged at the edge of the same finite ground plane 1, and the second conductor element of the first antenna 2 is arranged. 6 and the fourth conductor element 9 of the second antenna 3 are arranged in the same direction substantially parallel to the edge portion.
[0027]
In general, a conductor plate has a large current distribution at the edge portion. Therefore, when the antenna is disposed at the edge portion, a larger current is distributed at the edge portion. Therefore, when it arrange | positions like FIG. 6, the coupling | bonding between antennas becomes larger. The reason is that when the first and second antennas 2 and 3 are arranged at the edge, current leakage to the edge increases. Therefore, as shown in FIG. 6, when the first and second antennas 2 and 3 are arranged substantially in parallel and in the same direction at the edge of the finite ground plane 1, the coupling between the antennas can be further suppressed.
[0028]
FIG. 7 is a modification of FIG. 6 and shows an example in which the first antenna 2 is arranged on one of two adjacent sides of the finite ground plane 1 and the second antenna 3 is arranged on the other side. In this case, each antenna is arranged so as to be parallel to the edge of the ground plane 1, and either one of the second conductor element 6 and the fourth conductor element 9 is connected to the first and second feeding points 4. , 7 and the other tip is arranged on the opposite side of the second feeding point 7 with respect to the first feeding point 4 or the first feeding point 4 with respect to the second feeding point 7. What is necessary is just to arrange | position on the opposite side.
[0029]
Thus, in 2nd Embodiment, since the 1st and 2nd antennas 2 and 3 are arrange | positioned in the edge part of the ground plane 1, the inhibitory effect of the coupling between antennas can be heightened.
[0030]
(Third embodiment)
In the third embodiment, an auxiliary ground plate is disposed on the edge of the ground plate 1, and the first and second antennas 2 and 3 are disposed on the auxiliary ground plate.
[0031]
FIG. 8 is a schematic layout diagram of a third embodiment of an antenna array according to the present invention. As shown in the figure, an auxiliary ground plate 10 disposed at the edge of the ground plate 1 and first and second antennas 2 and 3 disposed at the edge of the auxiliary ground plate 10 are provided.
[0032]
Since the ground plane 1 and the auxiliary ground plane 10 are connected by capacitive coupling, the configuration is the same as that of the second embodiment shown in FIG. 7 in terms of high frequency. Therefore, by arranging the first conductor element 5 of the first antenna 2 and the second conductor element 6 of the second antenna 3 substantially parallel to the edge and in the same direction, as in the second embodiment, Binding can be suppressed more efficiently. Since the capacitive coupling in the case of FIG. 8 is weaker than that in the case where the first and second antennas 2 and 3 are directly connected to the ground plane 1, the inter-antenna coupling is smaller than that in the second embodiment.
[0033]
(Fourth embodiment)
In the above-described first to third embodiments, the example using the L-shaped antenna has been described. However, in the fourth to tenth embodiments described below, a T-shaped antenna is used.
[0034]
FIG. 9 is a schematic layout diagram of a fourth embodiment of an antenna array according to the present invention. The antenna array shown in FIG. 9 includes T-shaped first and second antennas 21 and 22 arranged on the ground plane 1. The first and second antennas 21 and 22 are arranged on substantially the same line. In addition, as shown in FIG. 10, you may arrange | position the 1st and 2nd antennas 21 and 22 a little. In this case, it is desirable to arrange the first and second antennas 21 and 22 in parallel so as not to overlap each other.
[0035]
The first antenna 21 includes a first feed point 23 on the ground plane 1, a first conductor element 24 that extends substantially perpendicular to the ground plane 1 from the first feed point 23, and a tip end portion of the first conductor element 24. A second conductor element 25 extending substantially parallel to the ground plane 1; and a third conductor element 26 extending from the tip of the first conductor element 24 to the opposite side of the second conductor element 25, and resonates at a first operating frequency. To do.
[0036]
The second antenna 22 includes a second feeding point 27 on the ground plane 1, a fourth conductor element 28 extending substantially perpendicularly to the ground plane 1 from the second feeding point 27, and a tip end portion of the fourth conductor element 28. A fifth conductor element 29 extending substantially parallel to the ground plane 1; and a sixth conductor element 30 extending from the tip of the fourth conductor element 28 to the opposite side of the fifth conductor element 29, and resonates at a second operating frequency. To do.
[0037]
The sum of the lengths of the second and third conductor elements 25 and 26 is approximately a half wavelength of the first operating frequency, and the sum of the lengths of the fifth and sixth conductor elements 29 and 30 is the second operating frequency. It is approximately half wavelength.
[0038]
By adjusting the ratio of the lengths of the first and second conductor elements 25 and 26 of the first antenna 21, the first antenna 21 can be matched to 50Ω, which is the impedance of the feeder line, at the first operating frequency. Similarly, by adjusting the ratio of the lengths of the fifth and sixth conductor elements 29 and 30 of the second antenna 22, the second antenna 22 is matched to 50Ω which is the impedance of the feeder line at the second operating frequency. Can do.
[0039]
FIGS. 11 and 12 are diagrams showing a configuration example of the first and second antennas 21 and 22. FIG. 11 is an example configured to be 50Ω at 1.9 GHz, and FIG. 12 is 50Ω at 2.1 GHz. An example configured as described above is shown.
[0040]
In the case of FIG. 11, the length of the first conductor element 24 is 6.5 mm, the length of the second conductor element 25 is 31.5 mm, and the length of the third conductor element 26 is 35.6 mm. φ is 0.8 mm. In the case of FIG. 12, the length of the first conductor element 24 is 7 mm, the length of the second conductor element 25 is 34 mm, the length of the third conductor element 26 is 38.5 mm, and the diameter φ of these conductor elements is 0.8 mm.
[0041]
The T-shaped antenna as shown in FIG. 10 has a feature that a large amount of current does not flow through the ground plane 1 as compared with the L-shaped antenna as shown in FIG.
[0042]
FIG. 13 is a diagram showing a radiation pattern of the T-shaped antenna. As can be seen from this figure, a null of the radiation pattern is directed in the longitudinal direction of the T-shaped antenna. Therefore, when the first and second antennas 21 and 22 are arranged on substantially the same line as shown in FIG. 10, since the null of the other antenna is directed to one antenna, the coupling between the antennas can be sufficiently suppressed.
[0043]
As described above, in the fourth embodiment, since the T-shaped antennas are arranged on substantially the same line, coupling between antennas hardly occurs, and radio wave interference hardly occurs.
[0044]
(Fifth embodiment)
In the fifth embodiment, two T-shaped antennas are arranged on the edge of the ground plane 1.
[0045]
FIG. 14 is a schematic layout diagram of a fifth embodiment of an antenna array according to the present invention. First and second antennas 21 and 22 having the same shape as in FIG. 10 are arranged at the edge of the finite ground plane 1. More specifically, the second, third, fifth, and sixth conductor elements 25, 26, 29, and 30 of the first and second antennas 21 and 22 are disposed substantially parallel to the edge portion.
[0046]
When the first and second antennas 21 and 22 are arranged at the edge of the finite ground plane 1, the image current flowing on the finite ground plane 1 becomes incomplete, and the radiation from the finite ground plane 1 decreases. Since this image current is in reverse phase with the current on the antenna, the radiated radio wave from the antenna is canceled out. However, the imperfection as described above suppresses the cancellation of the radiation from the antenna, and more The radiation from becomes larger.
[0047]
Further, nulls are directed in the respective conductor element directions of the first and second antennas 21 and 22 in FIG. 14 as in FIG. However, the degradation of coupling between antennas does not become so great.
[0048]
Thus, in the fifth embodiment, since the first and second antennas 21 and 22 are arranged at the edge of the finite ground plane 1, radiation from the finite ground plane 1 can be reduced, and the radiation characteristics of the antenna can be improved. .
[0049]
(Sixth embodiment)
In the sixth embodiment, an auxiliary ground plane 10 is arranged at the edge of the finite ground plane 1, and two T-shaped antennas are arranged at the edge of the auxiliary ground plane 10.
[0050]
FIG. 15 is a schematic layout diagram of a sixth embodiment of an antenna array according to the present invention. The antenna array of FIG. 15 includes an auxiliary ground plate 10 arranged at the edge of the finite ground plane 1 and first and second antennas 21 and 22 having the same shape as that of FIG. 10 arranged at the edge of the auxiliary ground plate 10. And. The second, third, fifth, and sixth conductor elements 25, 26, 29, and 30 of the first and second antennas 21 and 22 are disposed substantially parallel to the edge of the auxiliary ground plane 10.
[0051]
Since the finite ground plane 1 and the auxiliary ground plane 10 are connected by capacitive coupling, they have the same configuration as FIG. 14 in terms of high frequency. Further, since the auxiliary ground plane 10 is provided, the coupling through the finite ground plane 1 is weaker than that in FIG. 14, so that the coupling between antennas can be weaker than that in FIG. 14.
[0052]
As described above, in the sixth embodiment, the auxiliary ground plate 10 is provided at the peripheral portion of the finite ground plane 1, and the first and second antennas 21 and 22 are disposed at the peripheral portion of the auxiliary ground plate 10. Can be weakened, making it difficult for radio wave interference to occur.
[0053]
(Seventh embodiment)
Although omitted in the fifth and sixth embodiments, in this antenna as well, coupling occurs due to the current generated in the conductor element. FIG. 16 is a diagram schematically showing the current distribution of the T-shaped antenna shown in FIG. 10 for each frequency. The first antenna 21 has the second conductor element 25 longer than the third conductor element 26, and the resonance frequency is f1. In this case, the current distribution of the first antenna 21 changes greatly at a frequency lower and higher than the resonance frequency f1.
[0054]
As shown in FIG. 16, a large current distribution is generated in the second conductor element 25 at a frequency lower than the resonance frequency f1, and a large current distribution is generated in the third conductor element 26 at a frequency higher than the resonance frequency f1. It operates in the same manner as the L-shaped antenna described in the first embodiment at both lower and higher frequencies than the resonance frequency f1. That is, the T-shaped antenna functions equivalently as an L-shaped antenna whose direction changes as the frequency changes. For this reason, a separate measure from the first embodiment in which the L-shaped direction is fixed is required.
[0055]
Further, since the feeding point of the T-shaped antenna is located at the approximate center of the second and third conductor elements 25 and 26, the feeding point can be changed even if the orientation of the second and third conductor elements 25 and 26 is changed. The position of does not change. Therefore, in the L-shaped antenna, the feed point moves by changing the direction of the L-shape, so that the maximum current position changes greatly, and the strength of coupling between the antennas changes accordingly. do not do. For this reason, in the T-shaped antenna, it is only necessary to arrange a conductor element having a large current distribution among the second and third conductor elements 25 and 26 so as not to face the direction of the other antenna.
[0056]
FIG. 17 is a schematic layout diagram of the seventh embodiment of the antenna array according to the present invention. In FIG. 17, the operating frequency (first operating frequency) of the first antenna 21 is set lower than the operating frequency (second operating frequency) of the second antenna 22. Therefore, the sum of the lengths of the fifth and sixth conductor elements 29, 30 of the second antenna 22 is made shorter than the sum of the lengths of the second and third conductor elements 25, 26 of the first antenna 21. . Further, the fifth conductor element 29 is longer than the fourth conductor element 28, and the third conductor element 26 is longer than the second conductor element 25. With this configuration, the antenna-to-antenna coupling can be made smaller than in other antenna configurations under the above frequency conditions.
[0057]
FIG. 18 illustrates the first and second antennas 21 and 22 (the antenna is viewed from the normal direction of the ground plane 1 when the first operating frequency f # 1 is lower than the second operating frequency f # 2. In addition, the antennas 21 and 22 show all the mounting methods to the ground plane 1 that can be taken by # 1 and # 2 in the figure. Since the first operating frequency and the second operating frequency are different, the sizes of the first and second antennas 21 and 22 are different. That is, the second conductor element 25 has a different length from the third conductor element 26, and the fourth conductor element 28 has a different length from the fifth conductor element 29.
[0058]
As combinations of the arrangement methods of the first and second antennas 21 and 22, there are four types of models A to D in FIG. In the model A, the length of the second conductor element 25 <the length of the third conductor element 26 and the length of the fifth conductor element 29 <the length of the sixth conductor element 30 as in FIG. In the model B, the length of the second conductor element 25 <the length of the third conductor element 26 and the length of the fifth conductor element 29> the length of the sixth conductor element 30. In the model C, the length of the second conductor element 25> the length of the third conductor element 26, and the length of the fifth conductor element 29 <the length of the sixth conductor element 30. In the model D, the length of the second conductor element 25> the length of the third conductor element 26 and the length of the fifth conductor element 29> the length of the sixth conductor element 30.
[0059]
In FIG. 18, the conductor element described as “large” indicates that the current distribution in the frequency band is large. In FIG. 18, the current distribution before and after the first operating frequency (resonance frequency) f # 1 and the second operating frequency (resonance frequency) f # 2 can be grasped for each of the models A to D.
[0060]
As can be seen from FIG. 18, the place where the current distribution of the first antenna 21 is large and the place where the current distribution of the second antenna 22 is large are the model A. Therefore, if the first and second antennas 21 and 22 are arranged as in the model A, there is no possibility that the portion with a large current distribution faces each other and enters the closest state.
[0061]
FIG. 19 shows the maximum amount of coupling between antennas when the antenna arrays of models A to D are used and the distance between feeding points is 100 mm. As can be seen from this figure, in the band of frequencies f # 1 to f # 2, model A has weaker antenna coupling than other models.
[0062]
As described above, in the seventh embodiment, since the first and second antennas 21 and 22 are arranged so that the portions having a large current distribution face each other and do not approach each other, radio wave interference is less likely to occur.
[0063]
(Eighth embodiment)
In the eighth embodiment, the first antenna 21 is a transmitting antenna, the second antenna 22 is a receiving antenna, and the operating frequency (first operating frequency) f # 1 of the first antenna 21 is the operating frequency of the second antenna 22. (Second operating frequency) This is an antenna configuration when it is lower than f # 2.
[0064]
In such a case, wraparound from the transmitting antenna to the receiving antenna becomes the biggest problem. Therefore, it is necessary to configure the antenna array so that the coupling between antennas at the transmission frequency is reduced.
[0065]
Therefore, in the eighth embodiment, the fifth conductor element 29 of the second antenna 22 is made shorter than the sixth conductor element 30.
[0066]
In FIG. 18, it can be seen that by selecting the model A or C, the coupling between antennas in the vicinity of the first operating frequency f # 1 can be reduced. In the model A or C, since the fifth conductor element 29 is shorter than the sixth conductor element 30, the coupling between the antennas can be suppressed at the operating frequency f # 1 of the first antenna 21.
[0067]
As described above, in the eighth embodiment, when the transmission frequency is lower than the reception frequency, the fifth conductor element 29 of the second antenna 22 is made shorter than the sixth conductor element 30. Inter-antenna coupling can be suppressed and wraparound from the transmitting antenna to the receiving antenna can be avoided.
[0068]
(Ninth embodiment)
In the ninth embodiment, when the transmission frequency is higher than the reception frequency, wraparound from the transmission antenna to the reception antenna is avoided.
[0069]
In FIG. 18, when the frequency f is f # 2 <f <f # 1 or f # 2 <f, the second conductor element 25 of the first antenna 21 is replaced with the third conductor element in both models A and B. It is shorter than 26. With such a configuration, it is possible to suppress coupling between antennas in the vicinity of the transmission frequency f # 2.
[0070]
As described above, when the transmission frequency is higher than the reception frequency, the antenna-to-antenna coupling at the transmission frequency f # 2 is suppressed by making the second conductor element 25 of the first antenna 21 shorter than the third conductor element 26. It is possible to avoid the wraparound from the transmitting antenna to the receiving antenna.
[0071]
(Tenth embodiment)
In the tenth embodiment, when the operating frequency (first operating frequency) f # 1 of the first antenna 21 and the operating frequency (second operating frequency) f # 2 of the second antenna 22 are substantially the same, the model of FIG. In both A and Model D, the directions of the conductor elements of the first and second antennas 21 and 22 are the same. More specifically, the second conductor element 25 and the fifth conductor element 29 have the same length, and the third conductor element 26 and the sixth conductor element 30 have the same length.
[0072]
Thus, when the transmission frequency and the reception frequency are substantially the same, the first and second antennas 21 and 22 are oriented in substantially the same direction, the second conductor element 25 and the fifth conductor element 29 have the same length, and By making the third conductor element 26 and the sixth conductor element 30 have the same length, the coupling between antennas can be reduced.
[0073]
In the description of this patent, the conductor elements are all described as linear elements, but the effect is the same even if the elements are deformed as shown in FIG. In the antenna shown in FIG. 20, a conductor element substantially parallel to the ground plane is transformed into a helical type and a meander type. In the helical type, the central axis of the helical 31 is substantially parallel to the ground plane, and this direction is equivalent to the direction of the linear element. In the meander type, the direction of the portion where the meander element 32 is connected to the element perpendicular to the ground plane is equivalent to the direction of the linear element.
[0074]
【The invention's effect】
As described above in detail, according to the present invention, by adjusting the orientations of the first and second antennas 21 and 22, it is possible to reduce the coupling between the antennas and prevent radio wave interference. Therefore, even if a plurality of antennas for wireless devices are arranged in the same wireless device, wireless communication can be performed without interfering with each other.
[Brief description of the drawings]
FIG. 1 is a schematic layout diagram of an antenna array according to a first embodiment of the present invention.
FIG. 2 is a layout view showing a modification of FIG. 1;
FIG. 3 is a diagram showing matching characteristics and coupling characteristics of the first and second antennas 2 and 3;
FIG. 4 is a schematic diagram showing current distribution on the first and second antennas 2 and 3 of models A, B and C;
FIG. 5 is a schematic diagram showing a current distribution on the ground plane 1;
FIG. 6 is a schematic layout diagram of a second embodiment of an antenna array according to the present invention.
7 is a modification of FIG. 6 and shows an example in which the first antenna 2 is arranged on one of two adjacent sides of the finite ground plane 1 and the second antenna 3 is arranged on the other side.
FIG. 8 is a schematic layout diagram of a third embodiment of an antenna array according to the present invention.
FIG. 9 is a schematic layout diagram of a fourth embodiment of an antenna array according to the present invention.
10 is a layout view showing a modification of FIG. 9;
11 is a diagram showing a configuration example of first and second antennas 21 and 22. FIG.
12 is a diagram showing a configuration example of first and second antennas 21 and 22. FIG.
FIG. 13 is a diagram showing a radiation pattern of a T-shaped antenna.
FIG. 14 is a schematic layout view of an antenna array according to a fifth embodiment of the present invention.
FIG. 15 is a schematic layout diagram of a sixth embodiment of an antenna array according to the present invention;
16 is a diagram schematically showing the current distribution of the T-shaped antenna shown in FIG. 10 for each frequency.
FIG. 17 is a schematic layout view of an antenna array according to a seventh embodiment of the present invention.
FIG. 18 is a diagram showing all the mounting methods on the ground plane 1 that the first and second antennas 21 and 22 can take when the first operating frequency f # 1 is lower than the second operating frequency f # 2.
FIG. 19 is a diagram showing the maximum coupling amount between antennas when the antenna arrays of models A to D are used and the distance between feeding points is 100 mm.
FIG. 20 is a diagram showing the shape of the antenna array when the conductor element is deformed into a helical type and a meander type.
[Explanation of symbols]
1 Ground plane
2 First antenna
3 Second antenna
4 First feeding point
5 First conductor element
6 Second conductor element
7 Second feeding point
8 Third conductor element
9 Fourth conductor element
10 Auxiliary ground plane
21 First antenna
22 Second antenna
23 First feeding point
24 First conductor element
25 Second conductor element
26 Third conductor element
27 Second feeding point
28 Fourth conductor element
29 Fifth conductor element
30 sixth conductor element

Claims

A first feed point on the ground plane; a first conductor element extending substantially perpendicularly to the ground plane from the first feed point; and a second conductor element extending substantially parallel to the ground plane from a tip portion of the first conductor element And a third conductor element extending from the tip of the first conductor element to the opposite side of the second conductor element and having a length different from that of the second conductor element, and resonating at a first operating frequency. One antenna,
A second feeding point on the ground plane; a fourth conductor element extending substantially perpendicular to the ground plane from the second feeding point; and a fifth conductor extending substantially parallel to the ground plane from a tip portion of the fourth conductor element An element and a sixth conductor element extending from the tip of the fourth conductor element to the opposite side of the fifth conductor element and having a length different from the fifth conductor element, and resonates at a second operating frequency. A second antenna,
The sum of the lengths of the second and third conductor elements is approximately a half wavelength of the first operating frequency;
The sum of the lengths of the fifth and sixth conductor elements Ri substantially half-wave der of the second operating frequency,
The third conductor element is substantially parallel to the fifth conductor element and disposed between the first feeding point and the second feeding point ; and the first operating frequency is lower than the second operating frequency; and the second conductive element is shorter than the third conductive element, and the fifth conductive element rather short than the sixth conductive element,
The antenna array according to claim 5, wherein the fifth conductor element is disposed between the first feeding point and the second feeding point .

A first feed point on the ground plane; a first conductor element extending substantially perpendicularly to the ground plane from the first feed point; and a second conductor element extending substantially parallel to the ground plane from a tip portion of the first conductor element And a third conductor element extending from the tip of the first conductor element to the opposite side of the second conductor element and having a length different from that of the second conductor element, and resonating at a first operating frequency. One antenna,
A second feeding point on the ground plane; a fourth conductor element extending substantially perpendicular to the ground plane from the second feeding point; and a fifth conductor extending substantially parallel to the ground plane from a tip portion of the fourth conductor element An element and a sixth conductor element extending from the tip of the fourth conductor element to the opposite side of the fifth conductor element and having a length different from the fifth conductor element, and resonates at a second operating frequency. A second antenna,
The sum of the lengths of the second and third conductor elements is approximately a half wavelength of the first operating frequency;
The sum of the lengths of the fifth and sixth conductor elements is approximately a half wavelength of the second operating frequency;
The second conductor element is substantially parallel to the fifth conductor element and disposed between the first feeding point and the second feeding point, and the first operating frequency is lower than the second operating frequency, and The second conductor element is shorter than the third conductor element, and the fifth conductor element is shorter than the sixth conductor element;
The antenna array according to claim 5, wherein the fifth conductor element is disposed between the first feeding point and the second feeding point .

A first feed point on the ground plane; a first conductor element extending substantially perpendicularly to the ground plane from the first feed point; and a second conductor element extending substantially parallel to the ground plane from a tip portion of the first conductor element And a third conductor element extending from the tip of the first conductor element to the opposite side of the second conductor element and having a length different from that of the second conductor element, and resonating at a first operating frequency. One antenna,
A second feeding point on the ground plane; a fourth conductor element extending substantially perpendicular to the ground plane from the second feeding point; and a fifth conductor extending substantially parallel to the ground plane from a tip portion of the fourth conductor element An element and a sixth conductor element extending from the tip of the fourth conductor element to the opposite side of the fifth conductor element and having a length different from the fifth conductor element, and resonates at a second operating frequency. A second antenna,
The sum of the lengths of the second and third conductor elements is approximately a half wavelength of the first operating frequency;
The sum of the lengths of the fifth and sixth conductor elements is approximately a half wavelength of the second operating frequency;
The third conductive element, the fifth disposed between the substantially parallel and the first feeding point and the second feed-electric point in the conductor element, and wherein the first operating frequency is lower than the second operating frequency, and The second conductor element is shorter than the third conductor element, and the fifth conductor element is shorter than the sixth conductor element;
The antenna array according to claim 6, wherein the sixth conductor element is disposed between the first feeding point and the second feeding point .

The antenna array according to any one of claims 1 to 3 , wherein the first and second feeding points are arranged substantially in parallel with adjacent sides on the edge of the finite ground plane.

5. The antenna array according to claim 4 , wherein the first and second feeding points are respectively arranged substantially parallel to sides adjacent to adjacent edge portions of the finite ground plane.

An auxiliary ground plate provided separately from the ground plate at the edge of the ground plate,
The antenna array according to claim 4 or 5 , wherein the first and second feeding points are provided on the auxiliary ground plane.

The first antenna is a transmitting antenna;
The antenna array according to claim 1, wherein the second antenna is a receiving antenna.

A first radio that performs radio communication at a first operating frequency using a first antenna;
In a radio apparatus comprising: a second radio that performs radio communication at a second operating frequency using a second antenna;
The first antenna includes a first feed point on the ground plane, a first conductor element extending substantially perpendicularly to the ground plane from the first feed point, and a substantially parallel to the ground plane from a tip portion of the first conductor element. And a third conductor element extending from the tip of the first conductor element to the opposite side of the second conductor element and having a length different from that of the second conductor element. The two antennas include a second feeding point on the ground plane, a fourth conductor element extending substantially perpendicular to the ground plane from the second feeding point, and substantially parallel to the ground plane from a tip portion of the fourth conductor element. A fifth conductor element that extends, and a sixth conductor element that extends from the tip of the fourth conductor element to the opposite side of the fifth conductor element and has a length different from that of the fifth conductor element,
The sum of the lengths of the second and third conductor elements is approximately a half wavelength of the first operating frequency;
The sum of the lengths of the fifth and sixth conductor elements Ri substantially half-wave der of the second operating frequency,
The third conductor element is substantially parallel to the fifth conductor element and disposed between the first feeding point and the second feeding point ; and the first operating frequency is lower than the second operating frequency; and the second conductive element is shorter than the third conductive element, and the fifth conductive element rather short than the sixth conductive element,
The wireless device, wherein the fifth conductor element is disposed between the first feeding point and the second feeding point .