JP2004088136A

JP2004088136A - Laminated dielectric antenna

Info

Publication number: JP2004088136A
Application number: JP2002218943A
Authority: JP
Inventors: Yoshimasa Sugimoto; 杉本　好正
Original assignee: Kyocera Corp
Current assignee: Kyocera Corp
Priority date: 2002-06-26
Filing date: 2002-07-26
Publication date: 2004-03-18
Anticipated expiration: 2022-07-26
Also published as: JP3771878B2

Abstract

<P>PROBLEM TO BE SOLVED: To realize a laminated dielectric antenna having a low height and a wide band. <P>SOLUTION: The laminated dielectric antenna is provided with a dielectric layer 11; a rectangular radiation conductor 21 arranged on the top surface of the layer 11; a strip-like resistor 51 connected along one side of the conductor 21; a connection conductor 41 arranged to be passed through the layer 11 and having one end electrically connected to the conductor 21 at a position deviated parallel to the one side of the conductor 21 from the center of the conductor 21 including the resistor 51; and grounding conductor 31 arranged on the bottom surface of the layer 11 and having an opening 42 passed by the conductor 41 so as to be electrically insulated therefrom. The Q of the antenna is reduced due to the conductor loss of the conductor 51. Consequently, the bandwidth can be expanded without increasing the layer 11 in thickness, and the wide band and height areduction of the laminated dielectric antenna can be realized. Further, a strip-like resistor 52 may be preferably connected to one side opposite to the above one side. <P>COPYRIGHT: (C)2004,JPO

Description

【０００１】
【発明の属する技術分野】
本発明は、例えば携帯電話や無線ＬＡＮ等の無線通信機器、その他の各種通信機器等において使用される積層誘電体アンテナに関するものである。
【０００２】
【従来の技術】
例えば携帯電話や無線ＬＡＮ等の無線通信機器、その他の各種通信機器等において使用される、従来の積層誘電体アンテナを使用したアンテナとしてパッチアンテナが知られている（例えば、最新平面アンテナ技術、総合技術センター、１９９３年発行を参照）。その構造の一例を、図４に透視斜視図で、図５に透視平面図で示す。これらの図において、１１１は誘電体層、１２１は誘電体層１１１の上面に配された放射導体、１４１は誘電体層１１１を貫通して配され、一端が放射導体１２１と電気的に接続された接続導体、１３１は誘電体層１１１の下面に配され、接続導体１４１が電気的に絶縁されて貫通する開口部１４２を有する接地導体である。なお、図５においては誘電体層１１１の図示は省略している。
【０００３】
この従来の積層誘電体アンテナでは、接続導体１４１の接地導体１３１側の一端から高周波電流を給電することにより、放射導体１２１上に共振電流が生じて電波が放射されることによってアンテナとして用いることができる。
【０００４】
【発明が解決しようとする課題】
しかしながら、このような従来の積層誘電体アンテナにおいては、帯域幅を広げるためには誘電体層１１１の厚みを厚くする必要があり、広帯域化と低背化の両立が困難であるという問題点があった。
【０００５】
本発明は上記問題点に鑑みて案出されたものであり、その目的は、低背で広帯域な積層誘電体アンテナを提供することにある。
【０００６】
【課題を解決するための手段】
本発明の第１の積層誘電体アンテナは、誘電体層と、この誘電体層の上面に配された四角形状の放射導体と、この放射導体の一辺に沿って接続された帯状の抵抗体と、前記誘電体層を貫通して配され、一端が前記放射導体および前記抵抗体の全体の中心から前記一辺に平行にずれた位置で前記放射導体と電気的に接続された接続導体と、前記誘電体層の下面に配され、前記接続導体が電気的に絶縁されて貫通する開口部を有する接地導体とを具備することを特徴とするものである。
【０００７】
また、本発明の第２の積層誘電体アンテナは、前記放射導体の前記一辺に対向する辺にも帯状の抵抗体が接続され、前記接続導体の前記一端が前記放射導体および両方の前記抵抗体の全体の中心から前記一辺に平行にずれた位置で前記放射導体と電気的に接続されていることを特徴とするものである。
【０００８】
本発明の第１の積層誘電体アンテナによれば、接続導体の接地導体側の一端から高周波電流を給電することにより、放射導体および抵抗体上に共振電流が生じて電波が放射されるが、その共振電流の振幅が最大となる位置、すなわち放射導体の一辺に沿って帯状の抵抗体が配されており、放射導体および抵抗体の全体の中心から放射導体のこの一辺に平行にずれた位置で接続導体が接続されていることから、抵抗体の導体損によって共振電流が効果的に消費されてアンテナのＱが下がるので、反射特性を示す周波数特性曲線における共振点部分のピークをなだらかにすることができるため、放射効率は下がるものの帯域幅を広げることができる。
【０００９】
また、本発明の第２の積層誘電体アンテナによれば、放射導体の一辺に対向する辺にも帯状の抵抗体が接続され、接続導体の一端が放射導体および両方の抵抗体の全体の中心から放射導体の一辺に平行にずれた位置で放射導体と電気的に接続されていることから、両方の抵抗体の導体損によって共振電流がより一層効果的に消費されてアンテナのＱが下がるので、反射特性を示す周波数特性曲線における共振点部分のピークをよりなだらかにすることができるため、放射効率は下がるものの帯域幅をより一層広げることができる。
【００１０】
すなわち、本発明の積層誘電体アンテナによれば、従来の一般的に知られている広帯域化の手法としての誘電体層の厚みを厚くするといった方法に対して、誘電体層の厚みを厚くすることなく広帯域なアンテナを提供することができ、低背化にも対応することができるものとなる。
【００１１】
【発明の実施の形態】
以下、本発明の積層誘電体アンテナを図面を参照しつつ説明する。
【００１２】
図１（ａ）および（ｂ）ならびに図２（ａ）および（ｂ）は、それぞれ本発明の第１および第２の積層誘電体アンテナの実施の形態の一例を示す透視斜視図ならびに透視平面図である。これらの図において、１１は誘電体層、２１は誘電体層１１の上面に配された四角形状の放射導体、４１は誘電体層１１を貫通して配され、放射導体２１および抵抗体５１の全体の中心から放射導体２１の一辺に平行にずれた位置で一端が放射導体２１と電気的に接続された接続導体、５１は放射導体２１の一辺に沿って接続された帯状の抵抗体、５２はこの一辺に対向する辺に接続された帯状の抵抗体、３１は誘電体層１１の下面に配され、接続導体４１が電気的に絶縁されて貫通する開口部４２を有する接地導体である。なお、図２においては誘電体層１１を透視して接地導体３１を示している。
【００１３】
このように構成された本発明の第１の積層誘電体アンテナによれば、接続導体４１の接地導体３１側の一端から高周波電流を給電することにより、放射導体２１および抵抗体５１上に共振電流が生じて電波が放射されるが、その共振電流の振幅が最大となる位置、すなわち放射導体２１の一辺に沿って帯状の抵抗体５１が配されており、放射導体２１および抵抗体５１の全体の中心から放射導体２１のこの一辺に平行にずれた位置で接続導体４１が接続されていることから、抵抗体５１の導体損によって共振電流が効果的に消費されてアンテナのＱが下がるので、反射特性を示す周波数特性曲線における共振点部分のピークをなだらかにすることができるため、放射効率は下がるものの帯域幅を広げることができる。
【００１４】
また、本発明の第２の積層誘電体アンテナによれば、第１の積層誘電体アンテナの構成に加えて、放射導体２１の一辺に対向する辺に沿っても帯状の抵抗体５２が配されており、放射導体２１および抵抗体５１・５２の全体の中心から放射導体２１のこの一辺に平行にずれた位置で接続導体４１が接続されていることから、両方の抵抗体５１・５２の導体損によって共振電流がより一層効果的に消費されてアンテナのＱが下がるので、反射特性を示す周波数特性曲線における共振点部分のピークをよりなだらかにすることができるため、放射効率は下がるものの帯域幅をより一層広げることができる。
【００１５】
すなわち、これら本発明の積層誘電体アンテナによれば、従来の一般的に知られている広帯域化の手法としての誘電体層の厚みを厚くするといった方法に対して、誘電体層１１の厚みを厚くすることなく広帯域なアンテナを提供することができ、従って低背化にも対応することができるものとなる。
【００１６】
本発明の積層誘電体アンテナにおいては、積層誘電体アンテナ全体の外形が図１および図２に示すような略直方体状である場合には、放射導体２１をその形状に沿った形状の四角形状とすると、放射導体２１の面積を誘電体層１１の上面で十分に広く取ることができるので、周波数帯域をさらに広帯域化させることができる。
【００１７】
また、本発明の積層誘電体アンテナにおいては、抵抗体５１・５２（図１（ａ）および図２（ａ）に示す本発明の第１の積層誘電体アンテナについては抵抗体５１を、図１（ｂ）および図２（ｂ）に示す本発明の第２の積層誘電体アンテナについては抵抗体５１および５２を指す。以下同様。）の抵抗が大きいほど帯域幅を広げることができる。ただしその反面、抵抗を大きくしすぎると、帯域幅は広がるものの、放射効率が下がり、結果として利得が下がることとなるので、抵抗体５１・５２の抵抗値は、帯域幅および放射効率・利得に対する要求に応じて適切に設定する。
【００１８】
ここで、抵抗体５１の幅Ｗ５１および抵抗体５２の幅Ｗ５２を広くすると、抵抗が大きくなるので帯域幅を広げることができる。このとき、放射導体２１および抵抗体５１・５２の全体の中心と放射導体２１の接続導体４１が接続された位置とを通る線から放射導体２１の端に向かうに従って共振電流の振幅が大きくなり、共振電流の振幅が最大となる位置に抵抗体５１・５２を設けると、効果的に共振電流が消費されてアンテナのＱが下がるので、帯域幅を広げることができる。これに対し、放射導体２１および抵抗体５１・５２の全体の中心から放射導体２１および抵抗体５１・５２の全体の中心と放射導体２１の接続導体４１が接続された位置とを通る線の方向へ向かうに従って共振電流の振幅が小さくなり、この方向にある辺に抵抗体を設けてもその抵抗体ではあまり共振電流が消費されない。
【００１９】
なお、抵抗体５１・５２の幅Ｗ５１・Ｗ５２は、その抵抗体５１・５２の抵抗値が帯域幅および放射効率・利得に対する要求に応じた値となるように、抵抗体５１・５２の抵抗率を考慮して設定する。
【００２０】
また、抵抗体５１・５２の抵抗率を上げても抵抗が大きくなるので、抵抗率を上げることにより帯域幅を広げることができる。ただし、抵抗率を上げすぎると、帯域幅は広がるものの放射効率が下がり、結果として利得が下がるので、抵抗体５１・５２の抵抗率は、１Ω・ｍ以下で、十分な抵抗値を得るためには０．０００１Ω・ｍ以上（すなわち導電率では１Ｓ／ｍ以上１００００Ｓ／ｍ以下）であることが好ましい。
【００２１】
また、本発明の積層誘電体アンテナの接続導体４１は、図４および図５に示す従来の積層誘電体アンテナの接続導体１４１の位置と同様に、中心線から帯状の抵抗体と平行な方向に、放射導体２１の長さＬの約０．１５倍オフセットした位置に接続することで、インピーダンス整合が取れて高効率なアンテナとして動作させることができる。なお、図２（ａ）および（ｂ）にこのオフセット量をρ_０で示す。
【００２２】
また、本発明の積層誘電体アンテナの接続導体４１は、直径が小さいほど、インピーダンス整合を取りやすく周波数帯域やＶＳＷＲの調整がしやすいものとなる。
【００２３】
なお、接続導体４１の接続位置は、上述のように放射導体２１および抵抗体５１・５２の全体の中心から帯状の抵抗体５１・５２と平行な方向に、放射導体２１の長さＬの約０．１５倍オフセットした位置にするとよいので、接続導体４１を円柱状のものとして形成する場合には、その半径は放射導体２１の長さＬの０．１５倍以下に設定することが好ましい。また、接続導体４１の直径が小さすぎると抵抗が高くなるので、接続導体４１の直径は０．０５ｍｍ以上であることが好ましい。
【００２４】
本発明の積層誘電体アンテナを形成するに当たり、誘電体層１１・放射導体２１・接地導体３１・接続導体４１には、周知の高周波用配線基板に使用される種々の材料・形態のものと同様のものを使用することができる。
【００２５】
誘電体層１１としては、例えばアルミナセラミックス・ムライトセラミックス等のセラミックス材料やガラスセラミックス等の無機系材料、あるいは四フッ化エチレン−エチレン樹脂（ポリテトラフルオロエチレン；ＰＴＦＥ）・四フッ化エチレン−エチレン共重合樹脂（テトラフルオロエチレン−エチレン共重合樹脂；ＥＴＦＥ）・四フッ化エチレン−パーフルオロアルコキシエチレン共重合樹脂（テトラフルオロエチレン−パーフルオロアルキルビニルエーテル共重合樹脂；ＰＦＡ）等のフッ素樹脂やガラスエポキシ樹脂・ポリイミド等の樹脂系材料等が用いられる。これらの材料による誘電体層１１の形状や寸法（厚みや幅・長さ）は、使用される周波数や用途等に応じて設定される。
【００２６】
放射導体２１・接地導体３１・接続導体４１は、高周波信号伝送用の金属材料の導体層、例えばＣｕ層・Ｍｏ−Ｍｎのメタライズ層上にＮｉメッキ層およびＡｕメッキ層を被着させたもの・Ｗのメタライズ層上にＮｉメッキ層およびＡｕメッキ層を被着させたもの・Ｃｒ−Ｃｕ合金層・Ｃｒ−Ｃｕ合金層上にＮｉメッキ層およびＡｕメッキ層を被着させたもの・Ｔａ_２Ｎ層上にＮｉ−Ｃｒ合金層およびＡｕメッキ層を被着させたもの・Ｔｉ層上にＰｔ層およびＡｕメッキ層を被着させたもの、またはＮｉ−Ｃｒ合金層上にＰｔ層およびＡｕメッキ層を被着させたもの等を用いて、厚膜印刷法あるいは各種の薄膜形成方法やメッキ法等により形成される。その厚みや幅等も、伝送される高周波信号の周波数や用途等に応じて設定される。
【００２７】
抵抗体５１・５２を形成するための抵抗材料としては、抵抗温度係数が低く、また許容電流値が大きいものとして、例えばタングステン・レニウム・モリブデンやニクロム・窒化タンタルあるいはそれらの合金を用いることができる。中でも、タングステン−レニウム合金を用いると、抵抗温度係数が約１００×１０^−６／℃と低く、誘電体層１１にセラミックスを用いる場合に誘電体層１１との同時焼成が可能である点で好適なものとなる。
【００２８】
本発明の積層誘電体アンテナの作製方法としては、例えば誘電体層１１がガラスセラミックスから成る場合であれば、まず誘電体層１１となるガラスセラミックスのグリーンシートを準備し、これに所定の打ち抜き加工を施して接続導体４１としての貫通導体が配設される貫通孔を形成した後、スクリーン印刷法によりＣｕ等の導体ペーストを貫通孔に充填するとともに、放射導体２１・接地導体３１となる導体層のパターンおよび必要に応じてその他の所定の伝送線路パターン、ならびに抵抗体５１・５２となる抵抗体層のパターンを印刷塗布する。次に、８５０〜１０００℃で焼成を行ない、最後に各導体層の表面にＮｉメッキおよびＡｕメッキを施す。
【００２９】
図３（ａ）および（ｂ）は、それぞれ図１および図２に示す本発明の第１および第２の積層誘電体アンテナの実施の形態の一例についての反射特性を示す線図である。図３（ａ）および（ｂ）において、それぞれ横軸は周波数（単位：ＧＨｚ）、縦軸はＶＳＷＲであり、特性曲線は反射特性、すなわちＶＳＷＲの周波数特性を示している。この線図に示す反射特性は、電磁界シミュレーションを用いて得たものである。第１の積層誘電体アンテナの反射特性を示す図３（ａ）においては、ＶＳＷＲが２以下の帯域幅は１１３ＭＨｚであることが分かる。また、このときアンテナのＱは３２．２５である。また、第２の積層誘電体アンテナの反射特性を示す図３（ｂ）においては、ＶＳＷＲが２以下の帯域幅は１３４ＭＨｚとより一層広帯域化が図れることが分かる。また、このときアンテナのＱは２５．５である。
【００３０】
また、第１の積層誘電体アンテナの共振周波数である５．１６ＧＨｚにおける利得の最大値は−０．０７ｄＢｉであり、第２の積層誘電体アンテナの共振周波数である５．１０ＧＨｚにおける利得の最大値は−１．１５ｄＢｉであるが、抵抗体５１・５２の導電率をさらに下げる（すなわち、抵抗率をさらに上げる）と、帯域幅は広がるものの、放射効率が下がり、結果として利得が下がることとなる。
【００３１】
図３（ａ）および（ｂ）に示す反射特性を得た本発明の第１および第２の積層誘電体アンテナにおいては、誘電体層１１の厚み：Ｈ１１を１ｍｍ、放射導体２１の一辺の長さ：Ｌを８．９ｍｍ、放射導体の幅：Ｗ２１を８．４ｍｍ、抵抗体５１・５２の幅：Ｗ５１・Ｗ５２を０．５ｍｍ、放射導体２１および抵抗体５１・５２の全体の中心からのオフセット量：ρ_０を１．４ｍｍ（放射導体２１および抵抗体５１・５２の長さ：Ｌ＝８．９ｍｍの０．１６倍）、接続導体４１の直径を０．２ｍｍ、誘電体層１１の比誘電率を９．６、抵抗体５１・５２の導電率を１０００Ｓ／ｍとした。
【００３２】
また、図６は図４および図５に示す従来の積層誘電体アンテナの実施の形態の一例についての反射特性を示す線図である。図６においても、横軸は周波数（単位：ＧＨｚ）、縦軸はＶＳＷＲであり、特性曲線は反射特性、すなわちＶＳＷＲの周波数特性を示している。この線図に示す反射特性は、図３（ａ）および（ｂ）に示した結果を得るのに使用したものと同一の電磁界シミュレーションを用いて得たものである。この結果より、ＶＳＷＲが２以下の帯域幅は７５ＭＨｚであることが分かる。また、このときアンテナのＱは４３．３である。
【００３３】
図６に示す反射特性を得た従来の積層誘電体アンテナにおいては、誘電体層１１１の厚み：Ｈ１１１を１ｍｍ、放射導体１２１の一辺の長さ：Ｌ１２１を８．９ｍｍ、接続導体１４１の放射導体１４１の中心からのオフセット量：ρ_０を１ｍｍ（放射導体１２１の長さＬ１２１＝８．９ｍｍの０．１１倍）、接続導体１４１の直径を０．２ｍｍ、誘電体層１１の比誘電率を９．６とした。
【００３４】
なお、この従来の積層誘電体アンテナは、図３（ａ）および（ｂ）に示す結果を得た本発明の第１および第２の積層誘電体アンテナと比べて、放射導体１２１に抵抗体が形成されていない点の他はすべて同じ条件である。放射導体１２１の一辺の長さＬ１２１は本発明の積層誘電体アンテナにおける放射導体Ｌに等しくなっている。
【００３５】
以上より、帯域幅に関しては、図３（ａ）の結果を得た本発明の第１の積層誘電体アンテナでは１１３ＭＨｚ、また、図３（ｂ）の結果を得た本発明の第２の積層誘電体アンテナでは１３４ＭＨｚであるのに対して、図６の結果を得るのに用いた従来の積層誘電体アンテナでは７５ＭＨｚであり、本発明の積層誘電体アンテナの方が広帯域であることが分かる。また誘電体層の厚みに関しては、図３の結果を得た本発明の積層誘電体アンテナでは１ｍｍであるのに対して、図６の結果を得るのに用いた従来の積層誘電体アンテナでも１ｍｍとなり、本発明の積層誘電体アンテナと従来の積層誘電体アンテナは同じ厚みである。すなわち、図１および図２に示す本発明の積層誘電体アンテナによれば、厚みを厚くすることなく広帯域なアンテナを提供することができ、従って、アンテナの低背化にも対応できるものであることが分かる。
【００３６】
なお、本発明は以上の実施の形態の例に限定されるものではなく、本発明の要旨を逸脱しない範囲で種々の変更が可能である。例えば、放射導体を接地導体に対向する位置に複数個配してもよく、そのような構成にすると、各放射導体で共振を起こさせて、多周波共用特性を得ることができる。
【００３７】
【発明の効果】
本発明の第１の積層誘電体アンテナによれば、誘電体層と、この誘電体層の上面に配された四角形状の放射導体と、この放射導体の一辺に沿って接続された帯状の抵抗体と、前記誘電体層を貫通して配され、一端が前記放射導体および前記抵抗体の全体の中心から前記一辺に平行にずれた位置で前記放射導体と電気的に接続された接続導体と、前記誘電体層の下面に配され、前記接続導体が電気的に絶縁されて貫通する開口部を有する接地導体とを具備することから、接続導体の接地導体側の一端から高周波電流を給電することにより放射導体および抵抗体上に生じる共振電流の振幅が最大となる位置に抵抗体が配されることとなり、抵抗体の導体損によって共振電流が効果的に消費されてアンテナのＱが下がるので、反射特性を示す周波数特性曲線における共振点部分のピークをなだらかにすることができるため、放射効率は下がるものの帯域幅を広げることができる。
【００３８】
また、本発明の第２の積層誘電体アンテナによれば、前記放射導体の前記一辺に対向する辺にも帯状の抵抗体が接続され、前記接続導体の前記一端が前記放射導体および両方の前記抵抗体の全体の中心から前記一辺に平行にずれた位置で前記放射導体と電気的に接続されていることから、接続導体の接地導体側の一端から高周波電流を給電することにより放射導体および抵抗体上に生じる共振電流の振幅が最大となる位置に抵抗体が配されることとなり、両方の抵抗体の導体損によって共振電流がより一層効果的に消費されてアンテナのＱが下がるので、反射特性を示す周波数特性曲線における共振点部分のピークをよりなだらかにすることができるため、放射効率は下がるものの放射導体の一辺に沿って接続された帯状の抵抗体としたときより、より一層帯域幅を広げることができる。
【００３９】
すなわち、本発明の積層誘電体アンテナによれば、従来の一般的に知られている広帯域化の手法としての誘電体層の厚みを厚くするといった方法に対して、誘電体層の厚みを厚くすることなく広帯域なアンテナを提供することができ、低背化にも対応することができるものとなる。
【００４０】
以上により、本発明によれば、低背で広帯域な積層誘電体アンテナを提供することができた。
【図面の簡単な説明】
【図１】（ａ）および（ｂ）は、それぞれ本発明の第１の積層誘電体アンテナおよび本発明の第２の積層誘電体アンテナの実施の形態の一例を示す透視斜視図である。
【図２】（ａ）および（ｂ）は、それぞれ本発明の第１の積層誘電体アンテナおよび本発明の第２の積層誘電体アンテナの実施の形態の一例を示す透視平面図である。
【図３】（ａ）および（ｂ）は、それぞれ本発明の第１の積層誘電体アンテナおよび本発明の第２の積層誘電体アンテナの反射特性の一例を示す線図である。
【図４】従来の積層誘電体アンテナの一例を示す透視斜視図である。
【図５】従来の積層誘電体アンテナの一例を示す透視平面図である。
【図６】従来の積層誘電体アンテナの反射特性の一例を示す線図である。
【符号の説明】
１１・・・誘電体層
２１・・・放射導体
３１・・・接地導体
４１・・・接続導体
４２・・・開口部
５１、５２・・・抵抗体[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a laminated dielectric antenna used in wireless communication devices such as mobile phones and wireless LANs, and various other communication devices.
[0002]
[Prior art]
For example, a patch antenna is known as an antenna using a conventional laminated dielectric antenna, which is used in a wireless communication device such as a mobile phone and a wireless LAN, and various other communication devices (for example, a latest planar antenna technology, Technical Center, published 1993). An example of the structure is shown in a perspective view in FIG. 4 and in a plan view in FIG. In these figures, 111 is a dielectric layer, 121 is a radiation conductor disposed on the upper surface of the dielectric layer 111, 141 is disposed penetrating the dielectric layer 111, and one end is electrically connected to the radiation conductor 121. The connection conductor 131 is disposed on the lower surface of the dielectric layer 111 and is a ground conductor having an opening 142 through which the connection conductor 141 is electrically insulated. Note that illustration of the dielectric layer 111 is omitted in FIG.
[0003]
In this conventional laminated dielectric antenna, a high-frequency current is supplied from one end of the connection conductor 141 on the ground conductor 131 side, so that a resonance current is generated on the radiation conductor 121 and radio waves are radiated, so that the antenna can be used as an antenna. it can.
[0004]
[Problems to be solved by the invention]
However, in such a conventional laminated dielectric antenna, it is necessary to increase the thickness of the dielectric layer 111 in order to widen the bandwidth, and it is difficult to achieve both a wide band and a low profile. there were.
[0005]
The present invention has been devised in view of the above problems, and an object of the present invention is to provide a low-profile, wide-band laminated dielectric antenna.
[0006]
[Means for Solving the Problems]
A first laminated dielectric antenna according to the present invention includes a dielectric layer, a rectangular radiation conductor disposed on an upper surface of the dielectric layer, and a band-shaped resistor connected along one side of the radiation conductor. A connection conductor disposed through the dielectric layer, one end of which is electrically connected to the radiation conductor at a position shifted from the center of the entirety of the radiation conductor and the resistor parallel to the one side, A ground conductor provided on the lower surface of the dielectric layer and having an opening through which the connection conductor is electrically insulated.
[0007]
Further, in the second laminated dielectric antenna of the present invention, a strip-shaped resistor is connected to a side of the radiation conductor opposite to the one side, and the one end of the connection conductor is connected to the radiation conductor and both of the resistors. Is electrically connected to the radiation conductor at a position shifted in parallel to the one side from the center of the whole.
[0008]
According to the first laminated dielectric antenna of the present invention, by supplying a high-frequency current from one end of the connection conductor on the ground conductor side, a resonance current is generated on the radiation conductor and the resistor, and a radio wave is radiated. A position where the amplitude of the resonance current is maximum, that is, a strip-shaped resistor is arranged along one side of the radiation conductor, and a position shifted from the center of the entire radiation conductor and the resistor in parallel with this one side of the radiation conductor. Since the connection conductor is connected, the resonance current is effectively consumed due to the conductor loss of the resistor, and the Q of the antenna is lowered. Therefore, the peak of the resonance point portion in the frequency characteristic curve showing the reflection characteristic is made gentle. Therefore, the radiation efficiency can be reduced, but the bandwidth can be increased.
[0009]
According to the second laminated dielectric antenna of the present invention, the band-shaped resistor is also connected to the side opposite to one side of the radiation conductor, and one end of the connection conductor is connected to the center of the entirety of the radiation conductor and both resistors. Since it is electrically connected to the radiating conductor at a position shifted in parallel to one side of the radiating conductor, the resonance current is more effectively consumed by the conductor loss of both resistors, and the Q of the antenna decreases, Since the peak of the resonance point portion in the frequency characteristic curve indicating the reflection characteristic can be made gentler, the radiation efficiency can be reduced but the bandwidth can be further widened.
[0010]
That is, according to the laminated dielectric antenna of the present invention, the thickness of the dielectric layer is increased as compared with the conventional method of increasing the thickness of the dielectric layer, which is generally known as a technique for widening the band. Thus, it is possible to provide a wide-band antenna without any problem, and to cope with a reduction in height.
[0011]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the laminated dielectric antenna of the present invention will be described with reference to the drawings.
[0012]
FIGS. 1A and 1B and FIGS. 2A and 2B are respectively a perspective view and a plan view showing an example of an embodiment of a first and second laminated dielectric antenna of the present invention. It is. In these figures, 11 is a dielectric layer, 21 is a rectangular radiation conductor disposed on the upper surface of the dielectric layer 11, 41 is disposed penetrating through the dielectric layer 11, and the radiation conductor 21 and the resistor 51 are formed. A connection conductor having one end electrically connected to the radiation conductor 21 at a position shifted in parallel to one side of the radiation conductor 21 from the center of the whole; 51, a strip-shaped resistor connected along one side of the radiation conductor 21; Is a strip-shaped resistor connected to the side opposite to this one side, and 31 is a ground conductor disposed on the lower surface of the dielectric layer 11 and having an opening 42 through which the connection conductor 41 is electrically insulated. In FIG. 2, the ground conductor 31 is shown through the dielectric layer 11.
[0013]
According to the first laminated dielectric antenna of the present invention configured as described above, the high-frequency current is supplied from one end of the connection conductor 41 on the ground conductor 31 side, so that the resonance current is supplied to the radiation conductor 21 and the resistor 51. Is generated and a radio wave is radiated, but the band-shaped resistor 51 is arranged along the position where the amplitude of the resonance current is maximized, that is, along one side of the radiation conductor 21. Since the connection conductor 41 is connected at a position shifted from the center of the radiation conductor 21 in parallel to this one side, the resonance current is effectively consumed by the conductor loss of the resistor 51, and the Q of the antenna is reduced. Since the peak of the resonance point portion in the frequency characteristic curve showing the reflection characteristic can be made gentle, the radiation efficiency can be reduced but the bandwidth can be widened.
[0014]
According to the second laminated dielectric antenna of the present invention, in addition to the configuration of the first laminated dielectric antenna, the band-shaped resistor 52 is also arranged along the side opposite to one side of the radiation conductor 21. Since the connecting conductor 41 is connected at a position shifted in parallel to this side of the radiating conductor 21 from the entire center of the radiating conductor 21 and the resistors 51 and 52, the conductors of both the resistors 51 and 52 are connected. Since the resonance current is more effectively consumed by the loss and the Q of the antenna is reduced, the peak of the resonance point portion in the frequency characteristic curve showing the reflection characteristic can be made gentler, so that the radiation efficiency is reduced but the bandwidth is reduced. Can be further expanded.
[0015]
That is, according to the laminated dielectric antenna of the present invention, the thickness of the dielectric layer 11 is reduced in comparison with the conventional method of increasing the thickness of the dielectric layer, which is generally known as a technique for widening the band. It is possible to provide a wideband antenna without increasing the thickness, and it is possible to cope with a reduction in height.
[0016]
In the laminated dielectric antenna of the present invention, when the outer shape of the entire laminated dielectric antenna is substantially a rectangular parallelepiped as shown in FIGS. 1 and 2, the radiation conductor 21 is formed into a rectangular shape along the shape. Then, since the area of the radiation conductor 21 can be made sufficiently large on the upper surface of the dielectric layer 11, the frequency band can be further widened.
[0017]
Further, in the laminated dielectric antenna of the present invention, the resistors 51 and 52 (the resistor 51 in the first laminated dielectric antenna of the present invention shown in FIG. 1A and FIG. 2 (b) and the second laminated dielectric antenna of the present invention shown in FIG. 2 (b) indicate resistors 51 and 52. The same applies to the following.) The larger the resistance, the wider the bandwidth. However, on the other hand, when the resistance is too large, the bandwidth is widened, but the radiation efficiency is reduced, and as a result, the gain is reduced. Therefore, the resistance values of the resistors 51 and 52 are determined with respect to the bandwidth and the radiation efficiency / gain. Set appropriately as required.
[0018]
Here, when the width W51 of the resistor 51 and the width W52 of the resistor 52 are increased, the resistance is increased, so that the bandwidth can be widened. At this time, the amplitude of the resonance current increases from the line passing through the center of the entirety of the radiation conductor 21 and the resistors 51 and 52 and the position where the connection conductor 41 of the radiation conductor 21 is connected to the end of the radiation conductor 21, If the resistors 51 and 52 are provided at positions where the amplitude of the resonance current is maximized, the resonance current is effectively consumed and the Q of the antenna is reduced, so that the bandwidth can be widened. On the other hand, the direction of a line passing from the entire center of the radiation conductor 21 and the resistors 51 and 52 to the entire center of the radiation conductor 21 and the resistors 51 and 52 and the position where the connection conductor 41 of the radiation conductor 21 is connected. The amplitude of the resonance current decreases as the distance increases, and even if a resistor is provided on a side in this direction, the resonance current is not so much consumed by the resistor.
[0019]
Note that the widths W51 and W52 of the resistors 51 and 52 are set so that the resistances of the resistors 51 and 52 have values corresponding to the requirements for the bandwidth and the radiation efficiency and gain. Set in consideration of.
[0020]
Further, since the resistance increases even if the resistivity of the resistors 51 and 52 is increased, the bandwidth can be widened by increasing the resistivity. However, if the resistivity is excessively increased, the bandwidth is widened but the radiation efficiency is reduced, and as a result, the gain is reduced. Therefore, the resistivity of the resistors 51 and 52 is 1 Ω · m or less, and in order to obtain a sufficient resistance value, Is preferably 0.0001 Ω · m or more (that is, 1 S / m or more and 10000 S / m or less in conductivity).
[0021]
The connection conductor 41 of the laminated dielectric antenna of the present invention is arranged in the direction parallel to the band-shaped resistor from the center line, similarly to the position of the connection conductor 141 of the conventional laminated dielectric antenna shown in FIGS. By connecting to a position offset by about 0.15 times the length L of the radiation conductor 21, impedance matching can be achieved and the antenna can be operated as a highly efficient antenna. Incidentally, in FIG. 2 (a) and (b) shows the offset amount [rho _0.
[0022]
The smaller the diameter of the connection conductor 41 of the laminated dielectric antenna of the present invention, the easier it is to achieve impedance matching, and the easier it is to adjust the frequency band and the VSWR.
[0023]
The connection position of the connection conductor 41 is approximately equal to the length L of the radiation conductor 21 in a direction parallel to the band-shaped resistors 51 and 52 from the entire center of the radiation conductor 21 and the resistors 51 and 52 as described above. When the connecting conductor 41 is formed in a cylindrical shape, the radius is preferably set to 0.15 times or less the length L of the radiating conductor 21 because the connecting conductor 41 is preferably formed at a position offset by 0.15 times. Further, if the diameter of the connection conductor 41 is too small, the resistance increases, so that the diameter of the connection conductor 41 is preferably 0.05 mm or more.
[0024]
In forming the laminated dielectric antenna of the present invention, the dielectric layer 11, the radiation conductor 21, the ground conductor 31, and the connection conductor 41 are the same as those of various materials and forms used for known high-frequency wiring boards. Can be used.
[0025]
As the dielectric layer 11, for example, ceramic materials such as alumina ceramics and mullite ceramics, inorganic materials such as glass ceramics, or ethylene tetrafluoride-ethylene resin (polytetrafluoroethylene; PTFE) / ethylene tetrafluoride-ethylene Fluorine resins and glass epoxy resins such as polymer resins (tetrafluoroethylene-ethylene copolymer resin; ETFE) and ethylene tetrafluoride-perfluoroalkoxyethylene copolymer resin (tetrafluoroethylene-perfluoroalkylvinyl ether copolymer resin; PFA) -A resin material such as polyimide is used. The shape and dimensions (thickness, width, and length) of the dielectric layer 11 made of these materials are set according to the frequency used, the application, and the like.
[0026]
The radiating conductor 21, the grounding conductor 31, and the connecting conductor 41 are formed by applying a Ni plating layer and an Au plating layer on a conductor layer of a metal material for transmitting a high-frequency signal, for example, a Cu layer / Mo-Mn metallized layer. Ni plating layer and Au plating layer deposited on W metallized layer Cr-Cu alloy layer Ni plating layer and Au plating layer deposited on Cr-Cu alloy layer Ta ₂ N A Ni-Cr alloy layer and an Au plating layer deposited on a layer; a Pt layer and an Au plating layer deposited on a Ti layer; or a Pt layer and an Au plating layer on a Ni-Cr alloy layer Is formed by a thick-film printing method, various thin-film forming methods, a plating method, or the like. The thickness, width, and the like are also set according to the frequency, use, and the like of the transmitted high-frequency signal.
[0027]
As a resistance material for forming the resistors 51 and 52, for example, tungsten / rhenium / molybdenum, nichrome / tantalum nitride, or an alloy thereof can be used as a material having a low temperature coefficient of resistance and a large allowable current value. . Among them, the use of a tungsten-rhenium alloy is preferable because the temperature coefficient of resistance is as low as about 100 × 10 ⁻⁶ / ° C., and when ceramics are used for the dielectric layer 11, simultaneous firing with the dielectric layer 11 is possible. It becomes something.
[0028]
As a method of manufacturing the laminated dielectric antenna of the present invention, for example, when the dielectric layer 11 is made of glass ceramic, first, a green sheet of glass ceramic to be the dielectric layer 11 is prepared, and a predetermined punching process is performed. To form a through hole in which a through conductor as the connection conductor 41 is provided, and then fill the through hole with a conductive paste such as Cu by a screen printing method, and form a conductor layer serving as the radiation conductor 21 and the ground conductor 31. The above pattern and, if necessary, other predetermined transmission line patterns and the pattern of the resistor layers to be the resistors 51 and 52 are printed and applied. Next, baking is performed at 850 to 1000 ° C., and finally, the surface of each conductor layer is subjected to Ni plating and Au plating.
[0029]
FIGS. 3A and 3B are diagrams showing reflection characteristics of the first and second laminated dielectric antennas according to the embodiments of the present invention shown in FIGS. 1 and 2, respectively. 3A and 3B, the horizontal axis represents the frequency (unit: GHz) and the vertical axis represents the VSWR, and the characteristic curve represents the reflection characteristic, that is, the frequency characteristic of the VSWR. The reflection characteristics shown in this diagram are obtained by using an electromagnetic field simulation. In FIG. 3A showing the reflection characteristics of the first laminated dielectric antenna, it can be seen that the bandwidth where VSWR is 2 or less is 113 MHz. At this time, Q of the antenna is 32.25. Further, in FIG. 3B showing the reflection characteristics of the second laminated dielectric antenna, it can be seen that the bandwidth where the VSWR is 2 or less can be further increased to 134 MHz. At this time, Q of the antenna is 25.5.
[0030]
The maximum value of the gain at the resonance frequency of 5.16 GHz of the first laminated dielectric antenna is -0.07 dBi, and the maximum value of the gain at the resonance frequency of 5.10 GHz of the second laminated dielectric antenna is obtained. Is -1.15 dBi, but when the conductivity of the resistors 51 and 52 is further reduced (that is, the resistivity is further increased), the bandwidth is widened, but the radiation efficiency is reduced, and as a result, the gain is reduced. .
[0031]
In the first and second laminated dielectric antennas of the present invention having the reflection characteristics shown in FIGS. 3A and 3B, the thickness of the dielectric layer 11 is 1 mm, and the length of one side of the radiation conductor 21 is 1 mm. Length: L is 8.9 mm, width of radiation conductor: 8.4 mm for W21, width of resistors 51 and 52: 0.5 mm for W51 and W52, and distance from the center of radiation conductor 21 and resistors 51 and 52 as a whole. Offset amount: ρ ₀ is 1.4 mm (length of radiation conductor 21 and resistors 51 and 52: 0.16 times L = 8.9 mm), connection conductor 41 has a diameter of 0.2 mm, and dielectric layer 11 has The relative permittivity was 9.6, and the conductivity of the resistors 51 and 52 was 1000 S / m.
[0032]
FIG. 6 is a diagram showing reflection characteristics of an example of the embodiment of the conventional laminated dielectric antenna shown in FIGS. 4 and 5. Also in FIG. 6, the horizontal axis is frequency (unit: GHz) and the vertical axis is VSWR, and the characteristic curve shows the reflection characteristic, that is, the frequency characteristic of VSWR. The reflection characteristics shown in this diagram were obtained by using the same electromagnetic field simulation as that used to obtain the results shown in FIGS. 3 (a) and 3 (b). From this result, it can be seen that the bandwidth where VSWR is 2 or less is 75 MHz. At this time, Q of the antenna is 43.3.
[0033]
In the conventional laminated dielectric antenna having the reflection characteristics shown in FIG. 6, the thickness of the dielectric layer 111: 1 mm for H111, the length of one side of the radiation conductor 121: 8.9 mm for L121, and the radiation conductor of the connection conductor 141. offset from the center of 141 (0.11 times the length L121 = 8.9 mm of the radiation conductor 121) [rho ₀ to 1 mm, 0.2 mm diameter of the connection conductor 141, the dielectric constant of the dielectric layer 11 It was set to 9.6.
[0034]
The conventional laminated dielectric antenna has a resistor in the radiation conductor 121 as compared with the first and second laminated dielectric antennas of the present invention that have obtained the results shown in FIGS. 3A and 3B. All conditions are the same except that they are not formed. The length L121 of one side of the radiation conductor 121 is equal to the radiation conductor L in the laminated dielectric antenna of the present invention.
[0035]
As described above, regarding the bandwidth, the first laminated dielectric antenna of the present invention that obtained the result of FIG. 3A was 113 MHz, and the second laminated dielectric antenna of the present invention that obtained the result of FIG. While the frequency of the dielectric antenna is 134 MHz, the frequency of the conventional laminated dielectric antenna used to obtain the result of FIG. 6 is 75 MHz, which indicates that the laminated dielectric antenna of the present invention has a wider band. The thickness of the dielectric layer is 1 mm in the laminated dielectric antenna of the present invention obtained in FIG. 3 and 1 mm in the conventional laminated dielectric antenna used in obtaining the result in FIG. Thus, the laminated dielectric antenna of the present invention and the conventional laminated dielectric antenna have the same thickness. That is, according to the laminated dielectric antenna of the present invention shown in FIGS. 1 and 2, it is possible to provide a broadband antenna without increasing the thickness, and therefore, it is possible to cope with a reduction in the height of the antenna. You can see that.
[0036]
It should be noted that the present invention is not limited to the above-described embodiments, and various changes can be made without departing from the gist of the present invention. For example, a plurality of radiating conductors may be arranged at a position facing the ground conductor. With such a configuration, resonance occurs in each radiating conductor, and multi-frequency common characteristics can be obtained.
[0037]
【The invention's effect】
According to the first laminated dielectric antenna of the present invention, the dielectric layer, the rectangular radiating conductor disposed on the upper surface of the dielectric layer, and the band-shaped resistor connected along one side of the radiating conductor A connection conductor disposed through the dielectric layer and one end of which is electrically connected to the radiation conductor at a position shifted from the center of the entirety of the radiation conductor and the resistor parallel to the one side. A ground conductor having an opening through which the connection conductor is electrically insulated and is provided on the lower surface of the dielectric layer, so that a high-frequency current is supplied from one end of the connection conductor on the ground conductor side. As a result, the resistor is disposed at a position where the amplitude of the resonance current generated on the radiation conductor and the resistor is maximized, and the resonance current is effectively consumed by the conductor loss of the resistor, thereby lowering the Q of the antenna. , Frequency showing reflection characteristics It is possible to smooth the peak of the resonance point portion in sexual curve, it is possible to widen the bandwidth of the radiation efficiency is lowered ones.
[0038]
According to the second laminated dielectric antenna of the present invention, a band-shaped resistor is also connected to the side of the radiation conductor opposite to the one side, and the one end of the connection conductor is connected to the radiation conductor and both of the radiation conductors. The radiating conductor is electrically connected to the radiating conductor at a position shifted in parallel to the one side from the center of the entire resistor. Since the resistor is arranged at the position where the amplitude of the resonance current generated on the body is maximum, the resonance current is more effectively consumed by the conductor loss of both resistors, and the Q of the antenna is reduced, so that the reflection is reduced. Because the peak of the resonance point in the frequency characteristic curve showing the characteristics can be made gentler, the radiation efficiency is reduced, but when a band-shaped resistor connected along one side of the radiation conductor is used. Ri can be expanded even more bandwidth.
[0039]
That is, according to the laminated dielectric antenna of the present invention, the thickness of the dielectric layer is increased in comparison with the conventional method of increasing the thickness of the dielectric layer, which is generally known as a method of broadening the band. Thus, it is possible to provide a wide-band antenna without any problem, and to cope with a reduction in height.
[0040]
As described above, according to the present invention, a low-profile and wide-band laminated dielectric antenna can be provided.
[Brief description of the drawings]
FIGS. 1A and 1B are perspective perspective views showing an example of an embodiment of a first laminated dielectric antenna of the present invention and a second laminated dielectric antenna of the present invention, respectively.
FIGS. 2A and 2B are perspective plan views showing an example of an embodiment of a first laminated dielectric antenna of the present invention and a second laminated dielectric antenna of the present invention, respectively.
FIGS. 3A and 3B are diagrams illustrating examples of reflection characteristics of a first laminated dielectric antenna of the present invention and a second laminated dielectric antenna of the present invention, respectively.
FIG. 4 is a perspective view showing an example of a conventional laminated dielectric antenna.
FIG. 5 is a perspective plan view showing an example of a conventional laminated dielectric antenna.
FIG. 6 is a diagram showing an example of the reflection characteristics of a conventional laminated dielectric antenna.
[Explanation of symbols]
11 Dielectric layer 21 Radiation conductor 31 Ground conductor 41 Connection conductor 42 Openings 51 and 52 Resistors

Claims

Dielectric layer, a rectangular radiation conductor disposed on the upper surface of the dielectric layer, a band-shaped resistor connected along one side of the radiation conductor, and disposed through the dielectric layer, A connection conductor electrically connected to the radiation conductor at a position one end of which is displaced parallel to the one side from the center of the entirety of the radiation conductor and the resistor; and a connection conductor disposed on a lower surface of the dielectric layer, And a ground conductor having an opening that is electrically insulated and penetrates the laminated dielectric antenna.

A strip-shaped resistor is also connected to the side of the radiation conductor opposite to the one side, and the one end of the connection conductor is shifted from the center of the radiation conductor and both of the resistors in parallel to the one side. 2. The laminated dielectric antenna according to claim 1, wherein the antenna is electrically connected to the radiation conductor.