JP4246868B2

JP4246868B2 - Dual mode antenna

Info

Publication number: JP4246868B2
Application number: JP36861199A
Authority: JP
Inventors: 晴久内田; 貴敬田代
Original assignee: Yokowo Co Ltd
Current assignee: Yokowo Co Ltd
Priority date: 1999-12-27
Filing date: 1999-12-27
Publication date: 2009-04-02
Anticipated expiration: 2019-12-27
Also published as: JP2001185949A

Description

【０００１】
【発明の属する技術分野】
本発明は、水平方向に大きな利得の放射モードを有し、しかも第１周波数帯とこれよりも高い周波数の第２周波数帯の２つの周波数帯を送受信できるようにしたデュアルモードアンテナに関するものである。
【０００２】
【従来の技術】
従来の携帯電話機のアンテナとして、使用する周波数帯に対して約１／４波長の電気長に設定したものが一般的に使用されている。また、車載用アンテナとしても、使用する周波数帯の約１／４波長のものが広く用いられている。これは、アンテナと給電線との整合が図り易く、接合部でのリターンロスが生じないようにするためである。また、アンテナの物理的長さをできるだけ短くして、携帯に便利であるようにするためでもある。そしてまた、車載用にあっては、車のボディーから外方に突出する長さをできるだけ短くして、他の物に当接などして破損されないようにするとともにデザイン的な要望によるものである。
【０００３】
また、従来の１本のアンテナで２つの周波数帯を送受信できるデュアルモードアンテナの一例として、１本のコイル状のアンテナの先端側の部分のピッチを密に巻回し基端側の部分のピッチを粗に巻回し、周波数の低い第１周波数帯に対しては全体がアンテナとして作用し、周波数の高い第２周波数帯に対しては基端側の部分のみがアンテナとして作用するようにしたものがある。また、コイルアンテナの軸心位置にポールアンテナを設け、コイルアンテナとポールアンテナをそれぞれ第１周波数帯と第２周波数帯のアンテナとして作用させるようにしたものもある。
【０００４】
【発明が解決しようとする課題】
ところで、車のボディーから外方に突出させて垂直または傾けて配設した約１／４波長の従来の車載用アンテナにあっては、このアンテナを水平方向から見た放射モードは、斜め上方に大きな利得が生じていて、水平方向に必ずしも充分な利得が得られていない。これは、車のボディーなどが大きな接地面として作用し、この接地面の効果により約１／４波長のアンテナにあっては指向方向が斜め上方となるためである。しかるに、携帯電話機にあっては、中継アンテナがそれほど高くない位置にあり、互いにほぼ水平方向の位置関係にある。そこで、水平方向に大きな利得が得られれば、最も効率的に信号を放射することができる。
【０００５】
また、上述した従来の途中でピッチを換えるコイル状のアンテナのデュアルモードアンテナは、高い周波数の第２周波数帯では、アンテナ全体の一部分しかアンテナとして作用せず、それだけアンテナ利得が低いものとなる不具合がある。また、従来のコイルアンテナの軸心位置にポールアンテナを組み合わせたものは、その機械的構造が複雑であるとともに、互いのアンテナが相互に干渉を生じ易く、所望のアンテナ特性を実験的に求めざるを得ず、設計の手間が煩雑である。
【０００６】
本発明は、かかる従来技術の事情に鑑みてなされたもので、水平方向に大きな利得の放射モードを有するとともに、１本のアンテナで周波数の異なる２つの周波数帯を送受信できるデュアルモードアンテナを提供することを目的とする。
【０００７】
【課題を解決するための手段】
かかる目的を達成するために、本発明のデュアルモードアンテナは、第１周波数帯とこれの２倍の周波数の第２周波数帯を送受信するデュアルモードアンテナであって、前記第１周波数帯の約１／２波長で垂直または傾けて配設される第１アンテナエレメントの基端部に、容量結合するように前記第２周波数帯の約１／４波長の第２アンテナエレメントを添設し、前記第１アンテナエレメントの基端を整合回路と前記第１周波数帯を通過させる第１フィルタ回路とを順次に直列に介装してアンテナ入出力端に接続し、前記第２アンテナエレメントの基端を前記第２周波数帯を通過させる第２フィルタ回路を介装して前記アンテナ入出力端に接続し、前記第１アンテナエレメントとこれと容量結合する第２アンテナエレメントで前記第２周波数帯の約５／４波長のアンテナとして作用するように構成されている。
【０００８】
また、第１周波数帯とこれより高い周波数の第２周波数帯を送受信するデュアルモードアンテナであって、前記第１周波数帯の約１／２波長で垂直または傾けて配設される第１アンテナエレメントの基端部に、容量結合するように第２アンテナエレメントを添設し、前記第１アンテナエレメントを先端側がコイルアンテナで基端側がポールアンテナの直列接続で形成し、前記第１アンテナエレメントの基端を整合回路と前記第１周波数帯を通過させる第１フィルタ回路とを順次に直列に介装してアンテナ入出力端に接続し、前記第２アンテナエレメントの基端を前記第２周波数帯を通過させる第２フィルタ回路を介装して前記アンテナ入出力端に接続し、前記第１アンテナエレメントの基端側の前記ポールアンテナとこれと容量結合する第２アンテナエレメントで前記第２周波数帯の約３／４波長のアンテナとして作用するように構成しても良い。
【０００９】
また、第１周波数帯とこれより高い周波数の第２周波数帯を送受信するデュアルモードアンテナであって、前記第１周波数帯の約１／２波長で垂直または傾けて配設される第１アンテナエレメントの基端部に、容量結合するように第２アンテナエレメントを添設し、前記第１アンテナエレメントを先端側が密に巻回したコイルアンテナで基端側が粗に巻回したコイルアンテナの直列接続で形成するとともにこの基端側のポールアンテナを前記第２周波数帯の約１／２波長とし、前記第１アンテナエレメントの基端を整合回路と前記第１周波数帯を通過させる第１フィルタ回路とを順次に直列に介装してアンテナ入出力端に接続し、前記第２アンテナエレメントの基端を前記第２周波数帯を通過させる第２フィルタ回路を介装して前記アンテナ入出力端に接続し、前記第１アンテナエレメントの基端側の前記粗に巻回したコイルアンテナとこれと容量結合する第２アンテナエレメントで前記第２周波数帯の約３／４波長のアンテナとして作用するように構成しても良い。
【００１０】
また、第１周波数帯とこれの約２倍の周波数の第２周波数帯を送受信するデュアルモードアンテナであって、前記第１周波数帯の約１／２波長で垂直または傾けて配設される第１アンテナエレメントの基端部に、第１導電部材を直列に接続し、この第１導電部材に容量結合するように前記第２周波数帯の約１／４波長のアンテナに相当する第２導電部材を添設し、前記第１導電部材と前記第２導電部材を囲みこれらと容量結合するように筒状導体からなる容量管を設けるとともにこれを接地し、前記第１導電部材の基端を整合回路と前記第１周波数帯を通過させる第１フィルタ回路とを順次に直列に介装してアンテナ入出力端に接続し、前記第２導電部材の基端を前記第２周波数帯を通過させる第２フィルタ回路を介装して前記アンテナ入出力端に接続し、前記第１アンテナエレメントと前記第１導電部材とこれと容量結合する前記第２導電部材で前記第２周波数帯の約５／４波長のアンテナに相当するように構成しても良い。
【００１１】
また、第１周波数帯とこれより高い周波数の第２周波数帯を送受信するデュアルモードアンテナであって、前記第１周波数帯の約１／２波長で垂直または傾けて配設される第１アンテナエレメントの基端部に、第１導電部材を直列に接続し、この第１導電部材に容量結合するように第２導電部材を添設し、前記第１導電部材と前記第２導電部材を囲みこれらと容量結合するように筒状導体からなる容量管を設けるとともにこれを接地し、前記第１アンテナエレメントを先端側がコイルアンテナで基端側がポールアンテナの直列接続で形成するとともにこの基端側のポールアンテナを前記第２周波数帯の約１／２波長とし、前記第１導電部材の基端を整合回路と前記第１周波数帯を通過させる第１フィルタ回路とを順次に直列に介装してアンテナ入出力端に接続し、前記第２導電部材の基端を前記第２周波数帯を通過させる第２フィルタ回路を介装して前記アンテナ入出力端に接続し、前記第１アンテナエレメントの基端側の前記ポールアンテナと前記第１導電部材とこれと容量結合する第２導電部材で前記第２周波数帯の約３／４波長のアンテナに相当するように構成しても良い。
【００１２】
また、第１周波数帯とこれより高い周波数の第２周波数帯を送受信するデュアルモードアンテナであって、前記第１周波数帯の約１／２波長で垂直または傾けて配設される第１アンテナエレメントの基端部に、第１導電部材を直列に接続し、この第１導電部材に容量結合するように第２導電部材を添設し、前記第１導電部材と前記第２導電部材を囲みこれらと容量結合するように筒状導体からなる容量管を設けるとともにこれを接地し、前記第１アンテナエレメントを先端側が密に巻回したコイルアンテナで基端側が粗に巻回したコイルアンテナの直列接続で形成するとともにこの基端側のコイルアンテナを前記第２周波数帯の約１／２波長とし、前記第１導電部材の基端を整合回路と前記第１周波数帯を通過させる第１フィルタ回路とを順次に直列に介装してアンテナ入出力端に接続し、前記第２導電部材の基端を前記第２周波数帯を通過させる第２フィルタ回路を介装して前記アンテナ入出力端に接続し、前記第１アンテナエレメントの基端側の粗に巻回したコイルアンテナと前記第１導電部材とこれと容量結合する第２導電部材で前記第２周波数帯の約３／４波長のアンテナに相当するように構成しても良い。
【００１３】
【発明の実施の形態】
以下、本発明の第１実施例を図１ないし図４を参照して説明する。図１は、本発明のデュアルモードアンテナの第１実施例の電気的構造図である。図２は、図１のアンテナの電流分布を示し、（ａ）は第１周波数帯の電流分布であり、（ｂ）は第２周波数帯の電流分布である。図３は、図１のアンテナのＶＳＷＲ特性図であり、（ａ）は第１周波数帯のＶＳＷＲであり、（ｂ）は第２周波数帯のＶＳＷＲである。図４は、図１のデュアルモードアンテナを正面から水平方向に見た放射モードを示し、（ａ）は第１周波数帯の放射モードであり、（ｂ）は第２周波数帯の放射モードである。
【００１４】
まず、第１実施例として、日本のＰＤＣ８００（８１０〜９６０ＭＨｚ）を第１周波数帯ｆ１に設定し、これよりも高い約２倍の周波数のＰＤＣ１５００（１４２９〜１５０１ＭＨｚ）を第２周波数帯ｆに設定して説明する。垂直または傾けられて配設され、第１周波数帯ｆ１に対して約１／２波長λ１のアンテナとして作用する第１アンテナエレメントの全体をポールアンテナ１０で形成し、その基端部にこれと容量結合するように第２アンテナエレメントとしてのコイルアンテナ１２が添設される。これは、図１に示すごとく、ポールアンテナ１０の基端部の横にコイルアンテナ１２を配設しても良いが、ポールアンテナ１０の基端部に遊嵌させてコイルアンテナ１２を配設しても良い。そして、ポールアンテナ１０の基端１０ａが、２つのキャパシタンス素子と１つのインダクタンス素子がπ型に組まれた整合回路１４と、この整合回路１４を形成する１つのキャパシタンス素子を共有してこれと他の１つのインダクタンス素子が逆Ｌ字状に組まれた第１フィルタ回路１６とを順次に介してアンテナ入出力端１８に接続される。整合回路１４は、第１周波数帯ｆ１に対して約１／２波長λ１の電気長に設定されたポールアンテナ１０の基端１０ａにおける高いインピーダンスを、低いインピーダンスに変換して給電線などと整合を図るように形成される。そして、第１フィルタ回路１６は、第１周波数帯ｆ１を通過させるとともに第２周波数帯ｆ２を阻止するように形成される。また、コイルアンテナ１２の基端は、２つのキャパシタンス素子と１つのインダクタンス素子がＴ型に組まれた第２フィルタ回路２０を介してアンテナ入出力端１８に接続される。この第２フィルタ回路２０は、第２周波数帯ｆ２を通過させるとともに第１周波数帯ｆ１を阻止するように形成される。
【００１５】
かかる構成において、コイルアンテナ１２の電気長を第２周波数帯ｆ２に対して約１／４波長λ２にするとともにコイルアンテナ１２とポールアンテナ１０との間に生ずる浮遊容量Ｃｆを適宜に設定することで、第２周波数帯ｆ２に対してポールアンテナ１０とコイルアンテナ１２および浮遊容量Ｃｆの全体で約５／４波長λ２のアンテナとして作用するようにする。そこで、図２（ａ）のごとく、第１周波数帯ｆ１に対してポールアンテナ１０が約１／２波長λ１のアンテナとして作用し、また図２（ｂ）のごとく、第２周波数帯ｆ２に対してポールアンテナ１０とコイルアンテナ１２および浮遊容量Ｃｆが約５／４波長λ２のアンテナとして作用し、第１周波数帯ｆ１と第２周波数帯ｆ２のいずれでもアンテナ入出力端１８には比較的に低いインピーダンスが生じて給電線などと容易に整合が図れる。そして、第１周波数帯ｆ１に対してポールアンテナ１０が１／２波長λ１の放射モードを示し、しかも第２周波数帯ｆ２は第１周波数帯ｆ１の約２倍の周波数であるので、ポールアンテナ１０には第２周波数帯ｆ２の約１波長λ２の電流分布が生じて、１波長λ２の放射モードが強く現れる。
【００１６】
発明者らの実験によれば、第１周波数帯ｆ１に対して、図３（ａ）のごとく、充分に低いＶＳＷＲが得られた。また、第２周波数帯ｆ２に対しても、図３（ｂ）のごとく、これも充分に低いＶＳＷＲが得られた。そして、アンテナを正面から水平方向に見た放射モードは、第１周波数帯ｆ１に対して、図４（ａ）のごとく、低い仰角に大きな利得が得られ、第２周波数帯ｆ２に対しても、図４（ｂ）のごとく、低い仰角に大きな利得が得られた。したがって、第１実施例にあっては、日本のＰＤＣ８００とＰＤＣ１５００のいずれの周波数帯をも送受信できるとともに水平方向に大きな利得を備えており、携帯電話のデュアルモードアンテナとして最適である。
【００１７】
次に、本発明の第２実施例を図５および図６を参照して説明する。図５は、本発明のデュアルモードアンテナの第２実施例の電気的構造図である。図６は、図５のアンテナの電流分布を示し、（ａ）は第１周波数帯の電流分布であり、（ｂ）は第２周波数帯の電流分布である。図５および図６において、図１および図２と同じまたは均等な部材には同じ符号を付けて重複する説明を省略する。
【００１８】
第２実施例において、第１実施例と相違するところは、第１アンテナエレメントの全体が単一で約１／２波長のポールアンテナ１０で形成するのに換えて、第１周波数帯ｆ１に対してして約１／２波長λ１の第１アンテナエレメント２２を、先端側がコイルアンテナ２４で基端側が第２周波数帯ｆ２の約１／２波長λ２のポールアンテナ２６を直列接続して形成したことにある。かかる構成で、第２周波数帯ｆ２に対して、第１アンテナエレメント２２の基端側のポールアンテナ２６とコイルアンテナ１２およびこれらの間に生ずる浮遊容量Ｃｆの全体で約３／４波長λ２のアンテナとして作用するように、ポールアンテナ２６とコイルアンテナ１２および浮遊容量Ｃｆが調整される。なお、第１アンテナエレメント２２の先端側のコイルアンテナ２４は、第２周波数帯ｆ２に対して充分に密なピッチで巻回されてアンテナとして作用しないようにされる。すると、第１周波数帯ｆ１に対して、図６（ａ）に示すごとく、第１アンテナエレメント２２の全体が約１／２波長λ１のアンテナとして作用し、水平方向に大きな利得が得られる。また、第２周波数帯ｆ２に対して、図６（ｂ）に示すごとく、第１アンテナエレメント２２の基端側のポールアンテナ２６で約１／２波長λ２の放射モードが強く生じ、やはり水平方向に大きな利得が得られる。
【００１９】
なお、上記第２実施例において、第１周波数帯ｆ１に対して約１／２波長の第１アンテナエレメント２２を先端側が密なピッチで巻回されたコイルアンテナで基端側が第２周波数帯ｆ２の約１／２波長λ２の粗なピッチで巻回されたコイルアンテナを直列接続して形成しても、同様な効果が得られる。また、上記第２実施例では、第２周波数帯ｆ２がちょうど第１周波数帯ｆ１の２倍であれば、第１アンテナエレメント２２の先端側と基端側を同じ電気長に設定すれば良い。
【００２０】
さらに、本発明の第３実施例を図７を参照して説明する。図７は、本発明のデュアルモードアンテナの第３実施例の電気的構造図である。図７において、図１と同じまたは均等な部材には同じ符号を付けて重複する説明を省略する。
【００２１】
第３実施例にあっては、第１アンテナエレメントの全体で第１周波数帯ｆ１に対して約１／２波長λ１に設定されるポールアンテナ１０の基端に、直線状の第１導電部材２８を直列に接続し、その基端が整合回路１４に接続される。そして、この第１導電部材２８に容量結合するように第２周波数帯ｆ２に対して約１／４波長λ２に設定されるコイル状の第２導電部材３０が配設され、その基端が第２フィルタ回路２０に接続される。さらに、第１導電部材２８と第２導電部材３０を囲みこれらと容量結合するように筒状導電体からなる容量管３２が設けられるとともに接地される。この容量管３２と第１導電部材２８および第２導電部材３０の間には、適宜な浮遊容量Ｃｆが生じる。また、第１導電部材２８と第２導電部材３０の間にも浮遊容量Ｃｆが生ずることは勿論である。
【００２２】
かかる構成において、第１周波数帯ｆ１に対してポールアンテナ１０が約１／２波長λ１のアンテナとして作用し、その基端１０ａのインピーダンスが第１導電部材２８を介して整合回路１４でインピーダンス変換され、これが第１フィルタ回路１６を介してアンテナ入出力端１８に与えられる。また、第２周波数帯ｆ２に対して、ポールアンテナ１０と第１導電部材２８と浮遊容量Ｃｆおよび第２導電部材３０全体で約５／４波長λ２のアンテナに相当するように作用させ、第２導電部材３０の基端の低いインピーダンスが第２フィルタ回路２０を介してアンテナ入出力端１８に与えられる。ここで、第２周波数帯ｆ２に対して、約１／４波長λ２に相当する第２導電部材３０は容量管３２で遮蔽されており、ポールアンテナ１０に約１波長λ２の放射モードが強く生ずる。そこで、第３実施例にあっては、第１周波数帯ｆ１と第２周波数帯ｆ２のいずれにあっても、水平方向に大きな利得が得られる。ここで、ポールアンテナ１０を第２周波数帯ｆ２の１波長λ２の電気長で作用させるためには、第１周波数帯ｆ１に対して第２周波数帯ｆ２がちょうど２倍の周波数であることが望ましい。そこで、この第３実施例にあっては、第２周波数帯ｆ２が第１周波数帯ｆ１のちょうど２倍である欧州のＧＳＭ（８８０〜９６０ＭＨｚ）とＤＣＳ（１７１０〜１８８０ＭＨｚ）の携帯電話機のデュアルモードアンテナとして最適である。
【００２３】
そしてさらに、本発明の第４実施例を図８を参照して説明する。図８は、本発明のデュアルモードアンテナの第４実施例の電気的構造図である。図８において、図７と同じまたは均等な部材には同じ符号を付けて重複する説明を省略する。
【００２４】
第４実施例において、第３実施例と相違するところは、ポールアンテナ１０の基端１０ａに、図７の線状の第１導電部材２８に換えて、第１周波数帯ｆ１に対して約１／４波長のコイル状の第１導電部材３４を接続し、その基端を第１周波数帯ｆ１を通過させる第１フィルタ回路１６に直接に接続したことにある。なお、図７における整合回路１４が省かれている。かかる構成において、容量管３２とコイル状の第１導電部材３４の間に浮遊容量Ｃｆが生じる。そして、第１周波数帯ｆ１に対してポールアンテナ１０と第１導電部材３４により約３／４波長のアンテナとして作用させるとともに、コイル状の第１導電部材３４のインダクタンス成分とこれと容量管３２の間に生ずる浮遊容量Ｃｆとにより適宜な整合回路が形成され、ポールアンテナ１０の基端１０ａの大きなインピーダンスが小さなインピーダンスに変換されて、第１フィルタ回路１６を介してアンテナ入出力端１８に与えられる。
【００２５】
そしてまた、本発明の第５実施例を図９を参照して説明する。図９は、本発明のデュアルモードアンテナの第５実施例の電気的構造図である。図９において、図７と同じまたは均等な部材には同じ符号を付けて重複する説明を省略する。
【００２６】
第５実施例において、第３実施例と相違するところは、第１アンテナエレメントの全体が単一で約１／２波長λ１のポールアンテナ１０に換えて、第１周波数帯ｆ１に対して約１／２波長λ１の第１アンテナエレメント２２を先端側がコイルアンテナ２４で基端側が第２周波数帯ｆ２に対して約１／４波長λ２のポールアンテナ２６の直列接続で形成したことにある。かかる構成において、第２周波数帯ｆ２に対して、第１アンテナエレメント２２の基端側のポールアンテナ２６と浮遊容量Ｃｆおよび第２導電部材３０の全体で約３／４波長λ２のアンテナに相当するように作用させる。そして、第１周波数帯ｆ１に対して第１アンテナエレメント２２の全体で約１／２波長λ１のアンテナとして作用し、また第２周波数帯ｆ２に対して第１アンテナエレメント２２の基端側のポールアンテナ２６で約１／２波長λ２の放射モードが強く生じ、第１周波数帯ｆ１と第２周波数帯ｆ２のいずれでも水平方向に大きな利得が得られる。
【００２７】
そしてさらに、本発明の第６実施例を図１０を参照して説明する。図１０は、本発明のデュアルモードアンテナの第６実施例の電気的構造図である。図１０において、図９と同じまたは均等な部材には同じ符号を付けて重複する説明を省略する。
【００２８】
第６実施例において、第５実施例と相違するところは、第１アンテナエレメント２２の基端２２ａに、図９の直線状の第１導電部材２８に換えて、第１周波数帯ｆ１に対して約１／４波長λ１のコイル状の第１導電部材３４を接続し、その基端を第１周波数帯ｆ１を通過させる第１フィルタ回路１６に直接に接続したことにある。なお、図９における整合回路１４が省かれている。かかる構成において、第１周波数帯ｆ１に対して、第１アンテナエレメント２２とコイル状の第１導電部材３４により約３／４波長λ１のアンテナに相当するように作用する。しかも、第１周波数帯ｆ１に対してコイル状の第１導電部材３４および容量管３２の間に生ずる浮遊容量Ｃｆにより整合回路が形成され、それによりインピーダンスが小さなものとなる。
【００２９】
なお、上記実施例では、第１周波数帯ｆ１と第２周波数帯ｆ２を、主として日本の携帯電話機の周波数帯であるＰＤＣ８００とＰＤＣ１５００に対応させて説明しているが、これに限られず、米国のＡＭＰＳやＰＣＳおよび欧州のＧＳＭやＤＣＳに対応するように設定しても良い。また、第２導電部材３０がコイル状でなく直線状などであっても良い。本発明のデュアルモードアンテナの用途としては、水平方向に大きな利得が必要である無線通信装置用のデュアルモードアンテナとして用いることができ、携帯電話機に限られず、業務用無線などのデュアルモードアンテナとしても好適であり、しかも車載用の移動局に限られず固定局のデュアルモードアンテナとしても好適である。
【００３０】
【発明の効果】
以上説明したように、本発明のデュアルモードアンテナは構成されているので、以下のごとき格別な効果を奏する。
【００３１】
請求項１記載のデュアルモードアンテナにあっては、第１周波数帯に対して第１アンテナエレメントを約１／２波長のアンテナとして作用させ、第２周波数帯に対して第１アンテナエレメントと第２アンテナエレメントと浮遊容量により約５／４波長のアンテナとして作用させるとともに第１アンテナエレメントで１波長の放射モードを強く生じさせる。そこで、第１周波数帯と第２周波数帯のいずれをも送受信できるとともに、水平方向に大きな利得の放射モードが得られ、互いに水平方向の位置関係にある携帯電話機などの無線通信装置のデュアルモードアンテナとして好適である。
【００３２】
請求項２または３記載のデュアルモードアンテナにあっては、第１周波数帯に対して第１アンテナエレメントに約１／２波長の電流分布とし、第２周波数帯に対して第１アンテナエレメントの基端側のポールアンテナまたは粗に巻回したコイルアンテナに約１／２波長の電流分布とすることができ、第１周波数帯および第２周波数帯のいずれでも水平方向に利得の大きな放射モードを得ることができる。しかも、第２周波数帯が第１周波数帯に対してちょうど２倍の周波数でなくて幾分ずれており、第２周波数帯が第１アンテナエレメントの全体で約１波長の電流分布とならないような場合に、第２周波数帯に対して基端側のポールアンテナまたは粗に巻回したコイルアンテナを所望の約１／２波長の電気長とすることで、１／２波長の放射モードを強く生じさせることができる。
【００３３】
請求項４記載のデュアルモードアンテナにあっては、第１周波数帯に対して第１アンテナエレメントを約１／２波長のアンテナとして作用させ、第２周波数帯に対して第１アンテナエレメントと第１導電部材とこれに浮遊容量で容量結合する第２導電部材の全体で約５／４波長のアンテナに相当させて、共振を図る。しかも、第１導電部材と第２導電部材は容量管により囲まれていて、放射素子として作用しない。そこで、第２周波数帯に対して、第１アンテナエレメントのみがアンテナとして作用し、これに約１波長の電流分布が生ずる。そこで、第１周波数帯および第２周波数帯のいずれであっても、水平方向に利得の大きな放射モードが得られる。
【００３４】
請求項５または６記載のデュアルモードアンテナにあっては、第１周波数帯に対して第１アンテナエレメントを約１／２波長のアンテナとして作用させ、第２周波数帯に対して第１アンテナエレメントの基端側のポールアンテナまたは粗の巻回したコイルアンテナと第１導電部材とこれに浮遊容量で容量結合する第２導電部材の全体で約３／４波長のアンテナに相当させる。そして、第１導電部材と第２導電部材は容量管に囲まれていて放射素子として作用しないので、第２周波数帯に対して第１アンテナエレメントの基端側のポールアンテナまたはコイルアンテナのみがアンテナとして作用し、これに約１／２波長の電流分布が生ずる。そこで、第１周波数帯および第２周波数帯のいずれであっても、水平方向の利得が大きくなる。
【００３５】
請求項７記載のデュアルモードアンテナにあっては、第１アンテナエレメントの基端に接続する第１導電部材をコイル状とし、そのインダクタンス成分とこれを囲む容量管との間に生ずる浮遊容量とにより整合回路を形成することができる。しかも、浮遊容量によるキャパシタンス成分は分布定数であり、この整合回路により、第１アンテナエレメントの基端に生じた大きなインピーダンスが信号経路で緩やかに変換されて小さなものとなり、それだけリターンロスが少ない。
【００３６】
請求項８記載のデュアルモードアンテナにあっては、第１アンテナエレメントの基端に接続する第１導電部材を第１周波数帯の約１／４波長としたので、第１周波数帯に対して、第１アンテナエレメントと第１導電部材で約３／４波長のアンテナに相当し、第１導電部材の基端に生ずるインピーダンスは小さく、給電線などに容易に整合を図ることができる。
【図面の簡単な説明】
【図１】本発明のデュアルモードアンテナの第１実施例の電気的構造図である。
【図２】図１のアンテナの電流分布を示し、（ａ）は第１周波数帯の電流分布であり、（ｂ）は第２周波数帯の電流分布である。
【図３】図１のアンテナのＶＳＷＲ特性図であり、（ａ）は第１周波数帯のＶＳＷＲであり、（ｂ）は第２周波数帯のＶＳＷＲである。
【図４】図１のデュアルモードアンテナを正面から水平方向に見た放射モードを示し、（ａ）は第１周波数帯の放射モードであり、（ｂ）は第２周波数帯の放射モードである。
【図５】本発明のデュアルモードアンテナの第２実施例の電気的構造図である。
【図６】図５のアンテナの電流分布を示し、（ａ）は第１周波数帯の電流分布であり、（ｂ）は第２周波数帯の電流分布である。
【図７】本発明のデュアルモードアンテナの第３実施例の電気的構造図である。
【図８】本発明のデュアルモードアンテナの第４実施例の電気的構造図である。
【図９】本発明のデュアルモードアンテナの第５実施例の電気的構造図である。
【図１０】本発明のデュアルモードアンテナの第６実施例の電気的構造図である。
【符号の説明】
１０、２６ポールアンテナ
１０ａ、２２ａ基端
１２、２４コイルアンテナ
１４整合回路
１６第１フィルタ回路
１８アンテナ入出力端
２０第２フィルタ回路
２２第１アンテナエレメント
２８第１導電部材
３０第２導電部材
３２容量管
３４コイル状の第１導電部材
ｆ１第１周波数帯
ｆ２第２周波数帯
Ｃｆ浮遊容量
λ１第１周波数帯の波長
λ２第２周波数帯の波長[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a dual mode antenna having a radiation mode with a large gain in the horizontal direction and capable of transmitting and receiving two frequency bands, a first frequency band and a second frequency band having a higher frequency. .
[0002]
[Prior art]
As an antenna of a conventional mobile phone, an antenna having an electrical length of about ¼ wavelength with respect to a frequency band to be used is generally used. As a vehicle-mounted antenna, one having a wavelength of about ¼ of the frequency band to be used is widely used. This is to make it easy to match the antenna and the feed line and prevent return loss at the joint. It is also for making the antenna physical length as short as possible so that it is convenient for carrying. In addition, in the case of in-vehicle use, the length protruding outward from the body of the car is made as short as possible so as not to be damaged by contact with other objects, and according to design requirements. .
[0003]
Also, as an example of a dual mode antenna that can transmit and receive two frequency bands with a single conventional antenna, the pitch of the distal end portion of one coiled antenna is tightly wound to reduce the pitch of the proximal end portion. Wound roughly, the whole acts as an antenna for the first frequency band having a low frequency, and only the base end side part acts as an antenna for the second frequency band having a high frequency. is there. Also, there is a type in which a pole antenna is provided at the axial center position of the coil antenna so that the coil antenna and the pole antenna act as antennas in the first frequency band and the second frequency band, respectively.
[0004]
[Problems to be solved by the invention]
By the way, in the case of a conventional on-vehicle antenna of about ¼ wavelength arranged so as to protrude outward from the body of the car, the radiation mode when the antenna is viewed from the horizontal direction is obliquely upward. A large gain is generated, and a sufficient gain is not always obtained in the horizontal direction. This is because a car body or the like acts as a large grounding surface, and due to the effect of the grounding surface, the directing direction is obliquely upward in an antenna of about ¼ wavelength. However, in a mobile phone, the relay antennas are not so high and are in a horizontal relationship with each other. Therefore, if a large gain is obtained in the horizontal direction, the signal can be radiated most efficiently.
[0005]
In addition, the conventional dual mode antenna, which is a coiled antenna whose pitch is changed during the above-described process, functions as an antenna only in a part of the entire antenna in the second frequency band of high frequency, and the antenna gain is low accordingly. There is. In addition, the conventional coil antenna combined with the pole antenna at the axial center position has a complicated mechanical structure, and the antennas tend to interfere with each other. The design effort is complicated.
[0006]
The present invention has been made in view of the circumstances of the prior art, and provides a dual mode antenna having a large gain radiation mode in the horizontal direction and capable of transmitting and receiving two frequency bands having different frequencies with a single antenna. For the purpose.
[0007]
[Means for Solving the Problems]
To achieve this object, a dual mode antenna of the present invention is a dual mode antenna that transmits and receives a first frequency band and a second frequency band that is twice as high as the first frequency band. A second antenna element having a wavelength of about ¼ of the second frequency band is attached to the base end portion of the first antenna element that is vertically or tilted at / 2 wavelength so as to be capacitively coupled. A base end of one antenna element is connected in series to a matching circuit and a first filter circuit that passes the first frequency band in series, and connected to the antenna input / output end, and the base end of the second antenna element is connected to the base A second filter circuit that passes the second frequency band is interposed in the antenna input / output terminal, and the second antenna element that is capacitively coupled to the first antenna element is connected to the second frequency. It is configured to act as an antenna of approximately 5/4 wavelength of.
[0008]
A dual mode antenna for transmitting and receiving a first frequency band and a second frequency band higher than the first frequency band, wherein the first antenna element is arranged vertically or inclined at about ½ wavelength of the first frequency band. A second antenna element is attached to the base end of the first antenna element so as to be capacitively coupled, and the first antenna element is formed by connecting a coil antenna on the front end side and a pole antenna on the base end side in series. A matching circuit and a first filter circuit that passes the first frequency band are sequentially connected in series to the antenna input / output terminal, and the base end of the second antenna element is connected to the second frequency band. A second filter circuit that is connected to the input / output end of the antenna through a second filter circuit that passes therethrough, and is coupled to the pole antenna on the base end side of the first antenna element and the second In antenna element may be configured to act as an antenna of approximately 3/4 wavelength of the second frequency band.
[0009]
A dual mode antenna for transmitting and receiving a first frequency band and a second frequency band higher than the first frequency band, wherein the first antenna element is arranged vertically or inclined at about ½ wavelength of the first frequency band. A second antenna element is attached to the base end portion of the first antenna element so as to be capacitively coupled, and the first antenna element is connected in series with a coil antenna in which the distal end side is closely wound and the proximal end side is roughly wound. And forming a pole antenna on the base end side to have a half wavelength of the second frequency band, and a matching circuit and a first filter circuit allowing the base end of the first antenna element to pass through the first frequency band. The antenna is inserted in series in series and connected to the antenna input / output end, and a second filter circuit that passes the second frequency band through the base end of the second antenna element. The roughly wound coil antenna on the base end side of the first antenna element connected to the output end and the second antenna element capacitively coupled thereto function as an antenna of about 3/4 wavelength in the second frequency band. You may comprise so that it may do.
[0010]
The dual-mode antenna transmits and receives a first frequency band and a second frequency band having a frequency approximately twice that of the first frequency band. The dual-mode antenna is arranged vertically or inclined at about ½ wavelength of the first frequency band. A first conductive member is connected in series to the base end portion of one antenna element, and a second conductive member corresponding to an antenna having a wavelength of about ¼ of the second frequency band so as to be capacitively coupled to the first conductive member. A capacitive tube made of a cylindrical conductor is provided so as to surround the first conductive member and the second conductive member and to be capacitively coupled to them, and this is grounded, and the base end of the first conductive member is aligned. A circuit and a first filter circuit that passes the first frequency band are sequentially interposed in series and connected to the antenna input / output end, and a base end of the second conductive member is passed through the second frequency band. Enter and exit the antenna through two filter circuits The first antenna element, the first conductive member, and the second conductive member that is capacitively coupled to the first antenna element and the first conductive member may be configured to correspond to an antenna of about 5/4 wavelength in the second frequency band. good.
[0011]
A dual mode antenna for transmitting and receiving a first frequency band and a second frequency band higher than the first frequency band, wherein the first antenna element is arranged vertically or inclined at about ½ wavelength of the first frequency band. A first conductive member is connected in series to the base end of the first conductive member, a second conductive member is attached so as to be capacitively coupled to the first conductive member, and the first conductive member and the second conductive member are enclosed. A capacity tube made of a cylindrical conductor is provided so as to be capacitively coupled to the ground, and this is grounded, and the first antenna element is formed by connecting a coil antenna on the distal end side and a series connection of a pole antenna on the proximal end side and a pole on the proximal end side The antenna is set to about ½ wavelength of the second frequency band, and a base circuit of the first conductive member is sequentially inserted in series with a matching circuit and a first filter circuit that passes the first frequency band. Connected to the input / output end, and connected to the antenna input / output end through a second filter circuit passing the second frequency band through the base end of the second conductive member, and the base end of the first antenna element The pole antenna on the side, the first conductive member, and the second conductive member capacitively coupled thereto may be configured to correspond to an antenna of about ¾ wavelength in the second frequency band.
[0012]
A dual mode antenna for transmitting and receiving a first frequency band and a second frequency band higher than the first frequency band, wherein the first antenna element is arranged vertically or inclined at about ½ wavelength of the first frequency band. A first conductive member is connected in series to the base end of the first conductive member, a second conductive member is attached so as to be capacitively coupled to the first conductive member, and the first conductive member and the second conductive member are enclosed. A capacity tube made of a cylindrical conductor is provided so as to be capacitively coupled to the ground, and this is grounded, and a series connection of a coil antenna in which the first antenna element is densely wound at the distal end side and the proximal end side is roughly wound And a first filter circuit that passes the first end of the first conductive member through the matching circuit and the first frequency band. In order Connected in series to the antenna input / output end, and connected to the antenna input / output end through a second filter circuit passing the second frequency band at the base end of the second conductive member, The coil antenna roughly wound on the base end side of the first antenna element, the first conductive member, and the second conductive member capacitively coupled thereto correspond to an antenna having about 3/4 wavelength of the second frequency band. You may comprise as follows.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, a first embodiment of the present invention will be described with reference to FIGS. FIG. 1 is an electrical structural diagram of a first embodiment of a dual mode antenna according to the present invention. 2 shows the current distribution of the antenna of FIG. 1, where (a) is the current distribution in the first frequency band, and (b) is the current distribution in the second frequency band. FIG. 3 is a VSWR characteristic diagram of the antenna of FIG. 1, wherein (a) is a VSWR in the first frequency band, and (b) is a VSWR in the second frequency band. 4 shows a radiation mode when the dual-mode antenna of FIG. 1 is viewed from the front in the horizontal direction, where (a) is a radiation mode in the first frequency band, and (b) is a radiation mode in the second frequency band. .
[0014]
First, as a first embodiment, Japanese PDC800 (810 to 960 MHz) is set to the first frequency band f1, and PDC1500 (1429 to 1501 MHz) having a frequency twice higher than this is set to the second frequency band f. To explain. The entire first antenna element, which is arranged vertically or tilted and acts as an antenna having a wavelength of about ½ wavelength λ1 with respect to the first frequency band f1, is formed by the pole antenna 10, and this and the capacitance are formed at the base end thereof. A coil antenna 12 as a second antenna element is attached so as to be coupled. As shown in FIG. 1, the coil antenna 12 may be disposed beside the base end portion of the pole antenna 10, but the coil antenna 12 is disposed by loosely fitting the base end portion of the pole antenna 10. May be. The base end 10a of the pole antenna 10 shares a matching circuit 14 in which two capacitance elements and one inductance element are assembled in a π-type, and one capacitance element forming the matching circuit 14, and the other. Are sequentially connected to the antenna input / output terminal 18 through the first filter circuit 16 assembled in an inverted L shape. The matching circuit 14 converts a high impedance at the base end 10a of the pole antenna 10 set to an electrical length of about ½ wavelength λ1 with respect to the first frequency band f1 to a low impedance to match with a feeder line or the like. It is formed as shown. The first filter circuit 16 is formed to pass the first frequency band f1 and block the second frequency band f2. The base end of the coil antenna 12 is connected to the antenna input / output end 18 via a second filter circuit 20 in which two capacitance elements and one inductance element are assembled in a T shape. The second filter circuit 20 is formed to pass the second frequency band f2 and block the first frequency band f1.
[0015]
In such a configuration, the electrical length of the coil antenna 12 is set to about ¼ wavelength λ2 with respect to the second frequency band f2, and the stray capacitance Cf generated between the coil antenna 12 and the pole antenna 10 is appropriately set. The pole antenna 10, the coil antenna 12, and the stray capacitance Cf as a whole function as an antenna having a wavelength of about ¼ wavelength λ2 with respect to the second frequency band f2. Therefore, as shown in FIG. 2A, the pole antenna 10 acts as an antenna of about ½ wavelength λ1 with respect to the first frequency band f1, and as shown in FIG. 2B, with respect to the second frequency band f2. Thus, the pole antenna 10, the coil antenna 12, and the stray capacitance Cf function as an antenna having a wavelength of about ¼ wavelength λ2, and the antenna input / output terminal 18 is relatively low in both the first frequency band f1 and the second frequency band f2. Impedance is generated and can be easily matched with the feeder. The pole antenna 10 exhibits a radiation mode of ½ wavelength λ1 with respect to the first frequency band f1, and the second frequency band f2 has a frequency about twice that of the first frequency band f1, so the pole antenna 10 Causes a current distribution of about one wavelength λ2 in the second frequency band f2, and a radiation mode of one wavelength λ2 appears strongly.
[0016]
According to the experiments by the inventors, a sufficiently low VSWR was obtained for the first frequency band f1, as shown in FIG. Further, as shown in FIG. 3B, a sufficiently low VSWR was obtained for the second frequency band f2. The radiation mode when the antenna is viewed from the front in the horizontal direction provides a large gain at a low elevation angle with respect to the first frequency band f1, as shown in FIG. As shown in FIG. 4B, a large gain was obtained at a low elevation angle. Therefore, the first embodiment can transmit and receive both frequency bands of Japanese PDC800 and PDC1500 and has a large gain in the horizontal direction, which is optimal as a dual mode antenna for a mobile phone.
[0017]
Next, a second embodiment of the present invention will be described with reference to FIGS. FIG. 5 is an electrical structural diagram of the second embodiment of the dual mode antenna of the present invention. FIG. 6 shows the current distribution of the antenna of FIG. 5, where (a) shows the current distribution in the first frequency band, and (b) shows the current distribution in the second frequency band. 5 and FIG. 6, the same or equivalent members as those in FIG. 1 and FIG.
[0018]
The second embodiment differs from the first embodiment in that the entire first antenna element is formed by a single pole antenna 10 having a wavelength of about ½ wavelength, and is different from the first frequency band f1. Thus, the first antenna element 22 having about ½ wavelength λ1 is formed by connecting in series the pole antenna 26 having about ½ wavelength λ2 in the second frequency band f2 on the distal end side and the coil antenna 24 on the distal end side. It is in. With such a configuration, with respect to the second frequency band f2, the pole antenna 26 and the coil antenna 12 on the proximal end side of the first antenna element 22 and the stray capacitance Cf generated between these antennas are about 3/4 wavelength λ2. As a result, the pole antenna 26, the coil antenna 12, and the stray capacitance Cf are adjusted. Note that the coil antenna 24 on the front end side of the first antenna element 22 is wound at a sufficiently dense pitch with respect to the second frequency band f2 so as not to function as an antenna. Then, for the first frequency band f1, as shown in FIG. 6A, the entire first antenna element 22 acts as an antenna of about ½ wavelength λ1, and a large gain is obtained in the horizontal direction. Further, as shown in FIG. 6B, a radiation mode of about ½ wavelength λ2 is strongly generated in the pole antenna 26 on the proximal end side of the first antenna element 22 with respect to the second frequency band f2, and is also in the horizontal direction. A large gain can be obtained.
[0019]
In the second embodiment, the first antenna element 22 having a wavelength of about ½ with respect to the first frequency band f1 is a coil antenna in which the distal end side is wound at a dense pitch, and the proximal end side is in the second frequency band f2. A similar effect can be obtained even if coil antennas wound at a coarse pitch of about ½ wavelength λ2 are connected in series. In the second embodiment, if the second frequency band f2 is just twice the first frequency band f1, the distal end side and the proximal end side of the first antenna element 22 may be set to the same electrical length.
[0020]
Furthermore, a third embodiment of the present invention will be described with reference to FIG. FIG. 7 is an electrical structural diagram of the third embodiment of the dual mode antenna of the present invention. In FIG. 7, the same or equivalent members as in FIG.
[0021]
In the third embodiment, the linear first conductive member 28 is formed at the base end of the pole antenna 10 that is set to about ½ wavelength λ1 with respect to the first frequency band f1 in the entire first antenna element. Are connected in series, and the base end thereof is connected to the matching circuit 14. A coil-shaped second conductive member 30 set to about ¼ wavelength λ2 with respect to the second frequency band f2 is disposed so as to be capacitively coupled to the first conductive member 28, and its base end is the first end. 2 is connected to the filter circuit 20. Further, a capacity tube 32 made of a cylindrical conductor is provided so as to surround the first conductive member 28 and the second conductive member 30 and to be capacitively coupled thereto, and is grounded. An appropriate stray capacitance Cf is generated between the capacity tube 32 and the first conductive member 28 and the second conductive member 30. Of course, stray capacitance Cf is also generated between the first conductive member 28 and the second conductive member 30.
[0022]
In such a configuration, the pole antenna 10 acts as an antenna of about ½ wavelength λ1 with respect to the first frequency band f1, and the impedance of the base end 10a is impedance-converted by the matching circuit 14 via the first conductive member 28. This is applied to the antenna input / output terminal 18 via the first filter circuit 16. Further, the second frequency band f2 is caused to act so that the pole antenna 10, the first conductive member 28, the stray capacitance Cf, and the second conductive member 30 as a whole correspond to an antenna having a wavelength of about ¼ wavelength λ2. A low impedance at the base end of the conductive member 30 is given to the antenna input / output end 18 via the second filter circuit 20. Here, with respect to the second frequency band f2, the second conductive member 30 corresponding to about ¼ wavelength λ2 is shielded by the capacity tube 32, and a radiation mode of about one wavelength λ2 is strongly generated in the pole antenna 10. . Therefore, in the third embodiment, a large gain can be obtained in the horizontal direction in any of the first frequency band f1 and the second frequency band f2. Here, in order for the pole antenna 10 to operate with an electrical length of one wavelength λ2 of the second frequency band f2, it is desirable that the second frequency band f2 is exactly twice the frequency of the first frequency band f1. . Therefore, in this third embodiment, the dual mode of the European GSM (880 to 960 MHz) and DCS (1710 to 1880 MHz) mobile phones in which the second frequency band f2 is exactly twice the first frequency band f1. Ideal as an antenna.
[0023]
Further, a fourth embodiment of the present invention will be described with reference to FIG. FIG. 8 is an electrical structural diagram of a fourth embodiment of the dual mode antenna of the present invention. In FIG. 8, the same or equivalent members as in FIG.
[0024]
The fourth embodiment is different from the third embodiment in that the base end 10a of the pole antenna 10 is replaced with the linear first conductive member 28 of FIG. 7 and about 1 with respect to the first frequency band f1. / 4 wavelength coil-shaped first conductive member 34 is connected, and the base end thereof is directly connected to the first filter circuit 16 that passes the first frequency band f1. Note that the matching circuit 14 in FIG. 7 is omitted. In this configuration, a stray capacitance Cf is generated between the capacity tube 32 and the coiled first conductive member 34. Then, the pole antenna 10 and the first conductive member 34 act on the first frequency band f1 as an antenna of about ¾ wavelength, and the inductance component of the coiled first conductive member 34 and the capacitance tube 32 An appropriate matching circuit is formed by the stray capacitance Cf generated therebetween, and the large impedance of the base end 10a of the pole antenna 10 is converted into a small impedance, which is given to the antenna input / output end 18 via the first filter circuit 16. .
[0025]
A fifth embodiment of the present invention will be described with reference to FIG. FIG. 9 is an electrical structural diagram of the fifth embodiment of the dual mode antenna of the present invention. In FIG. 9, the same or equivalent members as in FIG.
[0026]
The fifth embodiment is different from the third embodiment in that the entire first antenna element is replaced with a pole antenna 10 having a single wavelength of about ½ wavelength λ1, and about 1 for the first frequency band f1. This is because the first antenna element 22 having the / 2 wavelength λ1 is formed by series connection of the coil antenna 24 on the distal end side and the pole antenna 26 having the ¼ wavelength λ2 on the proximal end side with respect to the second frequency band f2. In such a configuration, the pole antenna 26 on the base end side of the first antenna element 22, the stray capacitance Cf, and the second conductive member 30 as a whole correspond to an antenna having a wavelength of about ¾ wavelength λ2 with respect to the second frequency band f2. To act as follows. The first antenna element 22 as a whole functions as an antenna having a half wavelength λ1 with respect to the first frequency band f1, and the pole on the proximal end side of the first antenna element 22 with respect to the second frequency band f2. The antenna 26 generates a strong radiation mode of about ½ wavelength λ2, and a large gain is obtained in the horizontal direction in both the first frequency band f1 and the second frequency band f2.
[0027]
Further, a sixth embodiment of the present invention will be described with reference to FIG. FIG. 10 is an electrical structural diagram of the sixth embodiment of the dual mode antenna of the present invention. In FIG. 10, the same or equivalent members as in FIG.
[0028]
The sixth embodiment differs from the fifth embodiment in that the base end 22a of the first antenna element 22 is replaced with the linear first conductive member 28 of FIG. 9 with respect to the first frequency band f1. The coil-shaped first conductive member 34 of about ¼ wavelength λ1 is connected, and the base end thereof is directly connected to the first filter circuit 16 that passes the first frequency band f1. Note that the matching circuit 14 in FIG. 9 is omitted. In such a configuration, the first frequency band f1 acts to correspond to an antenna having a wavelength of about ¼ wavelength λ1 by the first antenna element 22 and the coiled first conductive member 34. In addition, a matching circuit is formed by the stray capacitance Cf generated between the coil-shaped first conductive member 34 and the capacitance tube 32 with respect to the first frequency band f1, thereby reducing the impedance.
[0029]
In the above-described embodiment, the first frequency band f1 and the second frequency band f2 have been described mainly corresponding to the PDC800 and PDC1500 which are the frequency bands of Japanese mobile phones. You may set so that it may respond | correspond to AMPS, PCS, and European GSM and DCS. Further, the second conductive member 30 may be linear instead of coiled. The dual-mode antenna of the present invention can be used as a dual-mode antenna for a wireless communication device that requires a large gain in the horizontal direction, and is not limited to a mobile phone, but can also be used as a dual-mode antenna for commercial radio. It is also suitable as a dual mode antenna of a fixed station without being limited to a mobile station mounted on a vehicle.
[0030]
【The invention's effect】
As described above, since the dual mode antenna of the present invention is configured, the following special effects can be obtained.
[0031]
The dual mode antenna according to claim 1, wherein the first antenna element acts as an antenna of about ½ wavelength with respect to the first frequency band, and the first antenna element and the second antenna with respect to the second frequency band. The antenna element and stray capacitance act as an antenna of about 5/4 wavelength, and the first antenna element strongly generates a radiation mode of 1 wavelength. Therefore, a dual mode antenna of a wireless communication device such as a mobile phone that can transmit and receive both the first frequency band and the second frequency band and has a large gain radiation mode in the horizontal direction and is in a horizontal positional relationship with each other. It is suitable as.
[0032]
4. The dual mode antenna according to claim 2, wherein the first antenna element has a current distribution of about ½ wavelength with respect to the first frequency band, and the first antenna element has a base with respect to the second frequency band. A current distribution of about ½ wavelength can be obtained on the pole antenna on the end side or the coil antenna roughly wound, and a radiation mode having a large gain in the horizontal direction is obtained in both the first frequency band and the second frequency band. be able to. In addition, the second frequency band is not exactly twice the frequency of the first frequency band but is somewhat shifted so that the second frequency band does not have a current distribution of about one wavelength in the entire first antenna element. In this case, a 1 / 2-wavelength radiation mode is strongly generated by setting the pole antenna on the proximal end side relative to the second frequency band or a coil antenna roughly wound to a desired electrical length of about 1/2 wavelength. Can be made.
[0033]
5. The dual mode antenna according to claim 4, wherein the first antenna element acts as an antenna of about ½ wavelength with respect to the first frequency band, and the first antenna element and the first antenna with respect to the second frequency band. The whole of the conductive member and the second conductive member capacitively coupled to the conductive member by stray capacitance corresponds to an antenna having a wavelength of about 5/4 to achieve resonance. Moreover, the first conductive member and the second conductive member are surrounded by the capacity tube and do not act as a radiating element. Therefore, only the first antenna element acts as an antenna for the second frequency band, and a current distribution of about one wavelength is generated in this. Therefore, a radiation mode having a large gain in the horizontal direction can be obtained in either the first frequency band or the second frequency band.
[0034]
In the dual mode antenna according to claim 5 or 6, the first antenna element is caused to act as an antenna of about ½ wavelength with respect to the first frequency band, and the first antenna element with respect to the second frequency band. The base pole antenna or the coil coil antenna with the coarse winding, the first conductive member, and the second conductive member capacitively coupled to the first conductive member with stray capacitance are made to correspond to an antenna having about 3/4 wavelength. Since the first conductive member and the second conductive member are surrounded by the capacity tube and do not act as a radiating element, only the pole antenna or the coil antenna on the base end side of the first antenna element with respect to the second frequency band is the antenna. This produces a current distribution of about ½ wavelength. Therefore, the gain in the horizontal direction becomes large in both the first frequency band and the second frequency band.
[0035]
In the dual mode antenna according to claim 7, the first conductive member connected to the base end of the first antenna element is formed in a coil shape, and the stray capacitance generated between the inductance component and the capacitance tube surrounding the first conductive member. A matching circuit can be formed. In addition, the capacitance component due to the stray capacitance is a distributed constant, and by this matching circuit, the large impedance generated at the base end of the first antenna element is gently converted in the signal path to become small, and the return loss is small accordingly.
[0036]
In the dual mode antenna according to claim 8, since the first conductive member connected to the base end of the first antenna element is about ¼ wavelength of the first frequency band, The first antenna element and the first conductive member correspond to an antenna having a wavelength of about 3/4 wavelength, and the impedance generated at the base end of the first conductive member is small and can be easily matched to the feeder line.
[Brief description of the drawings]
FIG. 1 is an electrical structural diagram of a first embodiment of a dual mode antenna of the present invention.
2 shows the current distribution of the antenna of FIG. 1, where (a) is the current distribution in the first frequency band, and (b) is the current distribution in the second frequency band.
3 is a VSWR characteristic diagram of the antenna of FIG. 1, wherein (a) is a VSWR in the first frequency band, and (b) is a VSWR in the second frequency band. FIG.
4 shows a radiation mode when the dual-mode antenna of FIG. 1 is viewed from the front in the horizontal direction, where (a) is a radiation mode in the first frequency band, and (b) is a radiation mode in the second frequency band. .
FIG. 5 is an electrical structural diagram of a second embodiment of the dual mode antenna of the present invention;
6 shows the current distribution of the antenna of FIG. 5, where (a) is the current distribution in the first frequency band, and (b) is the current distribution in the second frequency band.
FIG. 7 is an electrical structural diagram of a third embodiment of the dual mode antenna of the present invention.
FIG. 8 is an electrical structural diagram of a fourth embodiment of the dual mode antenna of the present invention;
FIG. 9 is an electrical structural diagram of a fifth embodiment of the dual mode antenna of the present invention;
FIG. 10 is an electrical structural diagram of a sixth embodiment of the dual mode antenna of the present invention;
[Explanation of symbols]
10, 26 pole antenna
10a, 22a
12, 24 Coil antenna
14 Matching circuit
16 First filter circuit
18 Antenna input / output terminal
20 Second filter circuit
22 First antenna element
28 First conductive member
30 Second conductive member
32 capacity tube
34 Coiled first conductive member
f1 first frequency band
f2 Second frequency band
Cf stray capacitance
λ1 First frequency band wavelength
λ2 Second frequency band wavelength

Claims

A dual mode antenna that transmits and receives a first frequency band and a second frequency band having a frequency that is approximately twice as high as the first frequency band, and is arranged vertically or inclined at about ½ wavelength of the first frequency band. A second antenna element having a wavelength of about ¼ of the second frequency band is attached to the base end of the element so as to be capacitively coupled, and the base end of the first antenna element is connected to a matching circuit and the first frequency band. A first filter circuit that passes through the first antenna is connected in series to the antenna input / output end, and a second filter circuit that passes the second frequency band through the base end of the second antenna element is provided. Connected to the antenna input / output terminal, and the first antenna element and the second antenna element capacitively coupled thereto function as an antenna having a wavelength of about 5/4 of the second frequency band. Dual-mode antenna to butterflies.

A dual mode antenna that transmits and receives a first frequency band and a second frequency band that is higher than the first frequency band, and is a base of a first antenna element that is disposed vertically or inclined at about ½ wavelength of the first frequency band. A second antenna element having a wavelength of about ¼ wavelength of the second frequency band is attached to the end so as to be capacitively coupled, and the first antenna element is connected in series with a coil antenna on the distal end side and a pole antenna on the proximal end side. And forming a pole antenna on the base end side to have a half wavelength of the second frequency band, and a matching circuit and a first filter circuit allowing the base end of the first antenna element to pass through the first frequency band. The antenna is sequentially connected in series and connected to the antenna input / output terminal, and the second antenna element is connected to the antenna through a second filter circuit that passes the second frequency band. The pole antenna on the base end side of the first antenna element is connected to the input / output end, and the second antenna element that is capacitively coupled to the pole antenna is configured to function as an antenna having about 3/4 wavelength in the second frequency band. A dual-mode antenna characterized by

A dual mode antenna that transmits and receives a first frequency band and a second frequency band that is higher than the first frequency band, and is a base of a first antenna element that is disposed vertically or inclined at about ½ wavelength of the first frequency band. A second antenna element having a wavelength of about ¼ wavelength of the second frequency band is attached to the end portion so as to be capacitively coupled, and the proximal end side is rough with a coil antenna in which the first antenna element is tightly wound on the front end side. The coil antenna is formed by serial connection of coil antennas wound around and the coil antenna roughly wound on the base end side is set to about ½ wavelength of the second frequency band, and the base end of the first antenna element is a matching circuit. And a first filter circuit that passes the first frequency band are sequentially connected in series and connected to an antenna input / output terminal, and a base end of the second antenna element is allowed to pass the second frequency band. A second filter element is connected to the antenna input / output terminal via a two-filter circuit, and the second antenna element capacitively coupled to the second coil element on the base end side of the first antenna element and the second frequency. A dual mode antenna configured to act as an antenna having about 3/4 wavelength of the band.

A dual mode antenna that transmits and receives a first frequency band and a second frequency band having a frequency that is approximately twice as high as the first frequency band, and is arranged vertically or inclined at about ½ wavelength of the first frequency band. A first conductive member is connected in series to the base end of the element, and a second conductive member corresponding to an antenna having a wavelength of about ¼ of the second frequency band is added so as to be capacitively coupled to the first conductive member. And a capacitance tube made of a cylindrical conductor is provided so as to surround and capacitively couple the first conductive member and the second conductive member, and this is grounded, and the base end of the first conductive member is connected to the matching circuit. A first filter circuit that passes the first frequency band is connected in series to the antenna input / output end, and a second filter that passes the second frequency band through the base end of the second conductive member. A circuit is inserted at the antenna input / output end. Subsequently, the first antenna element, the first conductive member, and the second conductive member capacitively coupled thereto are configured to correspond to an antenna having a wavelength of about 5/4 of the second frequency band. Dual mode antenna.

A dual mode antenna that transmits and receives a first frequency band and a second frequency band that is higher than the first frequency band, and is a base of a first antenna element that is disposed vertically or inclined at about ½ wavelength of the first frequency band. A first conductive member is connected in series to the end portion, a second conductive member is attached so as to be capacitively coupled to the first conductive member, and the first conductive member and the second conductive member are surrounded by these and the capacitance. A capacitive tube made of a cylindrical conductor is provided so as to be coupled and grounded, and the first antenna element is formed by connecting a coil antenna on the distal end side and a serial connection of a pole antenna on the proximal end side, and a pole antenna on the proximal end side. The wavelength of the second frequency band is about ½, and the base end of the first conductive member is connected in series with a matching circuit and a first filter circuit that allows the first frequency band to pass through in series. Connected to the end, connected to the antenna input / output end through a second filter circuit that passes the second frequency band through the base end of the second conductive member, and on the base end side of the first antenna element A dual mode antenna comprising the pole antenna, the first conductive member, and a second conductive member capacitively coupled thereto, corresponding to an antenna having a wavelength of about 3/4 of the second frequency band.

A dual mode antenna that transmits and receives a first frequency band and a second frequency band higher than the first frequency band, and is a base of a first antenna element that is arranged vertically or inclined at about ½ wavelength of the first frequency band. A first conductive member is connected in series to the end portion, a second conductive member is attached so as to be capacitively coupled to the first conductive member, and the first conductive member and the second conductive member are surrounded by these and the capacitance. A capacity tube made of a cylindrical conductor is provided so as to be coupled and grounded, and the first antenna element is formed by a series connection of a coil antenna having a distal end side wound tightly and a coil antenna having a proximal end side roughly wound. In addition, the coil antenna roughly wound on the base end side is set to about ½ wavelength of the second frequency band, and the first end of the first conductive member is passed through the matching circuit and the first frequency band. Filter circuit Are connected in series to the antenna input / output end, and the second conductive member is connected to the antenna input / output end through a second filter circuit that passes the second frequency band. An antenna having a wavelength of about 3/4 of the second frequency band includes the roughly wound coil antenna on the base end side of the first antenna element, the first conductive member, and the second conductive member capacitively coupled thereto. A dual mode antenna that is configured to correspond to

7. The dual mode antenna according to claim 4, wherein the first conductive member is formed in a coil shape.

7. The dual mode antenna according to claim 4, wherein the first conductive member is formed to correspond to an antenna having a wavelength of about ¼ of the first frequency band, and the first antenna element and the first antenna A dual-mode antenna configured to correspond to an antenna of about 3/4 wavelength in the first frequency band with one conductive member.