JP2005039370A - Radio wave lens control apparatus - Google Patents

Radio wave lens control apparatus Download PDF

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Publication number
JP2005039370A
JP2005039370A JP2003197857A JP2003197857A JP2005039370A JP 2005039370 A JP2005039370 A JP 2005039370A JP 2003197857 A JP2003197857 A JP 2003197857A JP 2003197857 A JP2003197857 A JP 2003197857A JP 2005039370 A JP2005039370 A JP 2005039370A
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Prior art keywords
dielectric constant
liquid crystal
radio wave
capacitance
crystal cell
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JP2003197857A
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Japanese (ja)
Inventor
Hirokazu Kamoda
浩和 鴨田
Takao Kuki
孝夫 九鬼
Toshihiro Nomoto
俊裕 野本
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Japan Broadcasting Corp
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Nippon Hoso Kyokai NHK
Japan Broadcasting Corp
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Abstract

<P>PROBLEM TO BE SOLVED: To provide a radio wave lens control apparatus capable of easily adjusting a dielectric constant to a desired value. <P>SOLUTION: The apparatus has a structure provided with a voltage variable power supply 221 for applying power to a liquid crystal cell 214, a capacitance meter 222 for measuring the capacitance of the liquid crystal cell 214 connected to the power supply 221, a dielectric constant calculator 223 for calculating the dielectric constant of a liquid crystal contained in the liquid crystal cell 214 on the basis of the capacitance measured by the capacitance meter 222, a high-frequency dielectric constant converter 224 for converting the dielectric constant calculated by the calculator 223 into a dielectric constant in a desired frequency, an interface 225 for inputting a value to be set as the dielectric constant of the liquid crystal, and a comparator 226 for controlling the output voltage of a power supply 22 in a direction of matching the dielectric constant obtained by conversion of the section 224 with the value of the dielectric constant inputted via the interface 225. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

【０００１】
【発明の属する技術分野】
本発明は、液晶を用いて電波の伝搬方向等を調整するための電波レンズの制御用の電波レンズ制御装置に関する。
【０００２】
【従来の技術】
従来、マイクロ波やミリ波などの高周波の電波の伝搬方向を調整するものとして、液晶を用いた電波レンズが知られている（例えば、特許文献１、２参照）。
特許文献１に開示された電波レンズは、電波の伝搬方向や、ビームの形状などを調整するために用いる媒体として、液晶を用いるものであり、その構成を図４に概念的に示す。
【０００３】
電波レンズは、図４に示すように、液晶層１１０、短冊状をした第一の電極１２０、第二の電極１３０、および制御電源１４０によって構成されている。また、電波レンズを構成する液晶層および電極は、図４に示す順序で積層され、拡大図に示すように、各液晶セル１５０において、第一の電極１２０と第二の電極１３０との間には制御電源１４０が接続される。
【０００４】
ここで、第二の電極１３０は、アース等の所定の基準電位になっており、第一の電極１２０と第二の電極１３０との間に、制御電源１４０により制御電圧を印加できる構成となっている。この制御電源１４０によって印加される制御電圧を変えることで、液晶セル中の液晶の誘電率を調節し、電波レンズ全体で電波の伝搬方向やビームの形状などの制御を行うことができる。
【０００５】
この誘電率の調節は、第一の電極１２０と第二の電極１３０との間に印加される制御電圧を調整することによってできるが、この制御電圧と、液晶層の比誘電率の関係は、図５に一例を示すように線形ではないことが知られている。また、この関係は、液晶の種類や電波レンズの構造などに依存している。そのため、従来は、この関係を事前に測定するなどして明らかにし、その結果に基づいて、各液晶セル中の液晶が所望の誘電率になるように、制御電圧を制御することが行われていた。そして、制御電圧と液晶層の誘電率との関係を測定する方法として、各液晶セルの制御電圧をすべて同一にした状態で、電波レンズ全体を透過する電波の位相を測定することによって求める方法がある。
【０００６】
【特許文献１】
特願２００１−３８９９１０号公報
【特許文献２】
特公平３−６６８３号公報
【０００７】
【発明が解決しようとする課題】
しかし、このような従来の制御電圧と液晶層の誘電率との関係を測定して電波レンズを制御する技術では、電波暗室中で平面波の電波を発生させて測定を行う必要があり、測定が大掛かりになると共に、非常に手間がかかるという問題があった。
【０００８】
本発明はこのような問題を解決するためになされたもので、容易に所望の誘電率に調節することができる電波レンズ制御装置を提供することを目的とする。
【０００９】
【課題を解決するための手段】
以上の点を考慮して、請求項１に係る発明は、液晶セルに印加する電圧可変の電源と、前記電源に接続された前記液晶セルの静電容量を測定する容量計と、前記容量計が測定した静電容量に基づいて前記液晶セルに含まれる液晶の誘電率を算出する誘電率算出部と、前記誘電率算出部が算出した前記誘電率を所望の周波数における誘電率に換算する高周波誘電率換算部と、前記液晶の誘電率として設定すべき値を入力させるインタフェースと、前記高周波誘電率換算部が換算して得られた誘電率を、前記インタフェース経由で入力された誘電率の値に一致させる方向に前記電源の出力電圧の制御を行う比較器とを備えた構成を有している。
【００１０】
この構成により、容量計を用いて測定した静電容量に基づいて所望の周波数での誘電率が換算され、その誘電率に基づいて誘電率の制御を行うため、容易に所望の誘電率に調節することが可能な電波レンズ制御装置を実現することができる。
【００１１】
【発明の実施の形態】
以下、本発明の実施の形態について図面を用いて説明する。
図１は、本発明の実施の形態に係る電波レンズ制御装置のブロック構成を概念的に示す図である。なお、図１には、説明のために電波レンズの一部を拡大した図も示した。電波レンズ２１０は、短冊状の形状をした第一の電極２１１、第二の電極２１２、および液晶層２１３で構成されている。ここでは、一つの短冊状をした第一の電極２１１を囲み、第二の電極２１２と液晶層２１３を含む、図中に点線で示す部分２１４を液晶セルと呼ぶことにする。
【００１２】
図１における電波レンズ制御装置２２０は、電圧可変の低周波電源２２１、液晶セル２１４の静電容量を測定するための容量計２２２、容量計２２２が測定した静電容量の値から、液晶セル２１４中の液晶層２１３の低周波誘電率を算出する誘電率算出部２２３、誘電率算出部２２３で算出した低周波誘電率から高周波誘電率に換算するための高周波誘電率換算部２２４、液晶セル２１４の誘電率として設定したい誘電率を入力させるためのインタフェース２２５、高周波誘電率換算部２２４によって出力された誘電率とインタフェース２２５を介して入力された誘電率とを比較し、低周波電源２２１の電圧を制御するための信号を出力する比較器２２６、および比較器２２６の出力を低周波電源２２１に接続し、容量計２２２の出力を誘電率算出部２２３に連動して接続する切替スイッチ２２７により構成される。
【００１３】
ここで、低周波電源２２１は、液晶セル２１４の配向を制御するための電源で有り、図１に示す構成では、この低周波電源２２１を、静電容量を測定するための電源としても用いるようになっている。なお、図１に示すように容量計２２２を介して液晶セル２１４に接続されるのでなく、直接液晶セル２１４に接続される構成であっても良い。
【００１４】
また、図１に示す構成では、低周波電源２２１と容量計２２２が単独で液晶セル２１４に接続されているようになっているが、低周波電源２２１だけが液晶セル２１４毎に設けられ、容量計２２２は切替スイッチで切り替え、共通に用いるようにしても良い。図１には、１対の低周波電源２２１と容量計２２２が液晶セル２１４に接続された構成のみを代表として示し、他の液晶セル２１４に接続された低周波電源２２１と容量計２２２を省略して示した。
【００１５】
以下に、液晶層２１３を構成する液晶の性質について説明する。図２に概念的に示すように、液晶分子は、一般的に細長い形状をしており、液晶分子の長軸方向の誘電率ε１と、短軸方向の誘電率ε２とは、異なる（このことを異方性という。）。液晶に制御電圧を印加すると、その制御電圧の高さに応じて、液晶分子は、液晶分子の長軸方向が印加された制御電圧によって発生した電界方向と平行になるように配向しようとする。
【００１６】
ここで、印加される制御電圧は、直流でも、例えば１ｋＨｚ程度の低周波の交流でもよい。なお、電波レンズの液晶セル２１４は、制御電圧が印加されていないときに、液晶分子の長軸方向が、図３（ａ）に示すように、電極面に平行になるように予め配向処理されているものとする。このようにしておくことによって、制御電圧の上昇に応じて液晶分子の向きが、図３（ｂ）に示すように変化し、制御電圧が所定値以上になると、液晶分子の長軸が図３（ｃ）に示すように電極面とほぼ垂直な方向に配向することとなる。
【００１７】
すなわち、図３（ａ）に示す状態では、電極２１１、２１２と垂直方向の液晶層２１３の誘電率（電波レンズを通過する電波は、この方向の誘電率の影響を受ける）は、液晶分子の短軸方向の誘電率ε２となり、図３（ｃ）に示す状態では、電極２１１、２１２と垂直方向の液晶層２１３の誘電率は、液晶分子の長軸方向の誘電率ε１となる。また、図３（ｂ）に示す状態では、電極２１１、２１２と垂直方向の液晶層２１３の誘電率は、上記の両者の中間的な誘電率となる。このように、制御電圧の高低に応じて、液晶分子の配向状態が変化し、液晶層の誘電率が変わることとなる。
【００１８】
以下、本発明の実施の形態に係る電波レンズ制御装置の動作について説明する。
まず、低周波電源２２１が出力した制御電圧を容量計２２２経由で電波レンズ２１０を構成する液晶セル２１４に印加する。制御電圧が印加されると、液晶層２１３内の液晶分子は、制御電圧の高さに応じて配向し、液晶層２１３の誘電率が変化する。容量計２２２は、制御電圧に応じて誘電率が変化した液晶セルの静電容量を測定し、測定して得られた静電容量の情報を誘電率算出部２２３に出力する。
【００１９】
静電容量の情報が入力された誘電率算出部２２３は、入力された静電容量の情報に基づいて液晶層２１３の誘電率εを算出する。ここで、液晶層２１３の誘電率εの算出は、液晶セルの構造が既知であるため、可能であり、例えば、第一の電極２１１の面積が液晶層２１３の厚みに比べて十分大きいときには、式（１）に示す式に基づいて簡単に求めることができる。
【００２０】
ε＝ｄＣ／２Ｓ （１）
ここで、ｄは液晶層２１３の厚さ、Ｓは第一の電極２１１の面積、Ｃは容量計２２２によって測定された液晶セルの静電容量の値を表す。
【００２１】
誘電率算出部２２３が算出した誘電率は、低周波電源２２１の励振周波数での誘電率（低周波誘電率）であり、一般に、マイクロ波、ミリ波などの高周波帯での誘電率（高周波誘電率）とは異なる。しかし、各周波数帯での液晶の誘電率は、液晶の配向状態で一意に決まるので、本実施の形態においては、液晶の低周波誘電率が分かれば、その配向状態を知ることができ、配向状態から高周波誘電率を求めることができる。
【００２２】
高周波誘電率換算部２２４は、上記のようにして求められた液晶の低周波誘電率と高周波誘電率の関係を予め記憶しておき、この関係に基づいて低周波誘電率を高周波誘電率に換算する。具体的な例としては、長軸と短軸方向の低周波誘電率をそれぞれε１Ｌ、ε２Ｌとし、長軸と短軸方向の高周波誘電率をそれぞれε１Ｈ、ε２Ｈとすると、換算して得られる高周波誘電率εＨは、観測した低周波誘電率εＬを用いて、以下の式（２）に示すように求めることができる。
εＨ＝ε２Ｈ＋（εＬ−ε２Ｌ）（ε１Ｈ−ε２Ｈ）／（ε１Ｌ−ε２Ｌ）（２）
【００２３】
一方、インタフェース２２５を介して、電波レンズを制御するために設定する各液晶セル２１４の誘電率が入力される。換算によって高周波誘電率が得られ、インタフェース２２５を介して誘電率の設定値が入力されると、比較器２２６は、高周波誘電率と誘電率の設定値とを比較して、両者が一致するように、低周波電源２２１の電圧値を制御する。
【００２４】
以上のような制御をリアルタイムに行うことにより、液晶セルの誘電率を所望の大きさに調節することができる。そして、他の各液晶セルに対しても、同様な制御を行うことにより、電波レンズ全体として、所望の誘電率の分布に調整することができ、高周波の電磁波の伝搬方向を正確に制御することが可能となる。
【００２５】
すなわち、この電波レンズ制御装置２２０を用いることによって、図５に示されるような制御電圧と液晶層の誘電率の関係を事前に明らかにして、その結果を考慮して制御電圧の大きさを決定する必要がなく、容易に電波レンズの制御ができる。
【００２６】
ここで、本発明の電波レンズ制御装置では、予め液晶の低周波誘電率と高周波誘電率との関係を事前に明らかにしておく必要がある。しかし、これらの関係は材料定数で不変であるため、一度測定すればよい。すなわち、上記の式（２）のε１Ｌ、ε２Ｌ、ε１Ｈ、およびε２Ｈは、前もって測定しておき、テーブルとして参照できるようにしておく。また、用いるのが同じ材料の液晶であれば、上記の式（１）における液晶層の厚みｄと第一の電極２１１の面積Ｓの値を変更して誘電率算出部２２３に設定するだけでよい。
【００２７】
これに対して従来の技術では、同じ材料の液晶を用いても、電波レンズの電極の大きさや液晶層の厚さを変えるなど構造を変化させる度に、制御電圧と液晶の高周波誘電率との関係を事前に測定する必要があった。したがって、電波レンズの構造を変化させる度に煩雑な上記の測定を行わなければならなかった。
【００２８】
なお、本実施の形態では制御電源を低周波電源としたが、制御電源の周波数はこれに制限されるものではなく、液晶の配向を制御できる電源であればよく、直流、または液晶の配向の制御が可能な高周波帯の電源でも制御電源として用いることができる。
また、本発明における容量計とは、被測定物の静電容量を測定しうる手段を意味する。個々の電圧計や電流計の測定値から、被測定物の静電容量を計算で求める場合についても、本発明との関連では容量計として表記することとする。
【００２９】
以上説明したように、本発明の実施の形態に係る電波レンズ制御装置は、液晶を用いた電波レンズの制御において、従来必要であった、電極に加える制御電圧の大きさと液晶層の誘電率の関係を事前に測定する手間を省くことができる。
また、それらの複雑な関係を意識することなく、容易に誘電率を調整し、電波レンズを制御することができる。
また、電源と容量計は、他の構成部と分離可能であるため、電源と容量計を測定の必要な液晶セルに設けておき、切替スイッチを電気的接続の切り替えを行うことができ、操作性良く測定することができる。
【００３０】
【発明の効果】
以上説明したように、本発明は、容易に所望の誘電率に調節することが可能な電波レンズ制御装置を実現することができる。
【図面の簡単な説明】
【図１】本発明の第１の実施の形態に係る電波レンズ制御装置のブロック構成を示す図である。
【図２】液晶分子の誘電率の異方性について説明するための図である。
【図３】印加された電圧に応じて配向する液晶分子の様子を説明するための図である。
【図４】電波レンズの構成と、電波レンズを構成する液晶セル内の液晶の誘電率を制御する、従来の制御装置の構成とを示す図である。
【図５】液晶に印加される制御電圧と液晶の比誘電率との関係の一例を示す図である。
【符号の説明】
１１０、２１３ 液晶層
１２０、２１１ 第１の電極
１３０、２１２ 第２の電極
１４０ 制御電源
１５０、２１４ 液晶セル
２１０ 電波レンズ
２２０ 電波レンズ制御装置
２２１ 低周波電源
２２２ 容量計
２２３ 誘電率算出部
２２４ 高周波誘電率換算部
２２５ インタフェース
２２６ 比較器
２２７ 切替スイッチ[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a radio wave lens control device for controlling a radio wave lens for adjusting the propagation direction of radio waves using liquid crystal.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, radio wave lenses using liquid crystals are known as devices that adjust the propagation direction of high frequency radio waves such as microwaves and millimeter waves (see, for example, Patent Documents 1 and 2).
The radio wave lens disclosed in Patent Document 1 uses liquid crystal as a medium used for adjusting the propagation direction of radio waves, the shape of a beam, and the like, and its configuration is conceptually shown in FIG.
[0003]
As shown in FIG. 4, the radio wave lens includes a liquid crystal layer 110, a strip-shaped first electrode 120, a second electrode 130, and a control power source 140. In addition, the liquid crystal layer and the electrodes constituting the radio wave lens are stacked in the order shown in FIG. 4, and as shown in the enlarged view, in each liquid crystal cell 150, between the first electrode 120 and the second electrode 130. Is connected to a control power supply 140.
[0004]
Here, the second electrode 130 has a predetermined reference potential such as ground, and a control voltage can be applied between the first electrode 120 and the second electrode 130 by the control power supply 140. ing. By changing the control voltage applied by the control power supply 140, the dielectric constant of the liquid crystal in the liquid crystal cell can be adjusted, and the radio wave propagation direction, beam shape, and the like can be controlled by the entire radio wave lens.
[0005]
The dielectric constant can be adjusted by adjusting a control voltage applied between the first electrode 120 and the second electrode 130. The relationship between the control voltage and the relative dielectric constant of the liquid crystal layer is as follows. It is known that it is not linear as shown in FIG. Further, this relationship depends on the type of liquid crystal, the structure of the radio wave lens, and the like. For this reason, conventionally, this relationship has been clarified by, for example, measuring in advance, and based on the result, the control voltage is controlled so that the liquid crystal in each liquid crystal cell has a desired dielectric constant. It was. Then, as a method for measuring the relationship between the control voltage and the dielectric constant of the liquid crystal layer, there is a method for obtaining by measuring the phase of the radio wave transmitted through the entire radio wave lens with all the control voltages of the respective liquid crystal cells being the same. is there.
[0006]
[Patent Document 1]
Japanese Patent Application No. 2001-389910 [Patent Document 2]
Japanese Examined Patent Publication No. 3-6683 [0007]
[Problems to be solved by the invention]
However, in the conventional technology that controls the radio lens by measuring the relationship between the control voltage and the dielectric constant of the liquid crystal layer, it is necessary to generate a plane wave in the anechoic chamber and perform the measurement. There was a problem that it took a lot of time and was very troublesome.
[0008]
The present invention has been made to solve such a problem, and an object thereof is to provide a radio wave lens control device that can be easily adjusted to a desired dielectric constant.
[0009]
[Means for Solving the Problems]
In view of the above, the invention according to claim 1 is a voltage variable power source applied to the liquid crystal cell, a capacitance meter that measures the capacitance of the liquid crystal cell connected to the power source, and the capacitance meter. A dielectric constant calculating unit that calculates a dielectric constant of liquid crystal contained in the liquid crystal cell based on the measured capacitance, and a high frequency that converts the dielectric constant calculated by the dielectric constant calculating unit into a dielectric constant at a desired frequency. A dielectric constant conversion unit, an interface for inputting a value to be set as a dielectric constant of the liquid crystal, and a dielectric constant obtained by conversion by the high-frequency dielectric constant conversion unit are values of the dielectric constant input via the interface. And a comparator that controls the output voltage of the power supply in a direction that matches the power supply.
[0010]
With this configuration, the dielectric constant at the desired frequency is converted based on the capacitance measured using a capacitance meter, and the dielectric constant is controlled based on the dielectric constant, so it can be easily adjusted to the desired dielectric constant. It is possible to realize a radio wave lens control device that can do this.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a diagram conceptually showing a block configuration of a radio wave lens control apparatus according to an embodiment of the present invention. FIG. 1 also shows an enlarged view of a part of the radio wave lens for explanation. The radio wave lens 210 includes a strip-shaped first electrode 211, second electrode 212, and liquid crystal layer 213. Here, a portion 214 surrounded by a dotted line in the drawing, which surrounds one strip-shaped first electrode 211 and includes the second electrode 212 and the liquid crystal layer 213, is referred to as a liquid crystal cell.
[0012]
The radio wave lens control device 220 in FIG. 1 includes a low-frequency power source 221 having a variable voltage, a capacitance meter 222 for measuring the capacitance of the liquid crystal cell 214, and a capacitance value measured by the capacitance meter 222. A dielectric constant calculator 223 for calculating the low frequency dielectric constant of the liquid crystal layer 213 in the inside, a high frequency dielectric constant converter 224 for converting the low frequency dielectric constant calculated by the dielectric constant calculator 223 to a high frequency dielectric constant, and a liquid crystal cell 214. The dielectric constant output by the interface 225 for inputting the dielectric constant desired to be set as the dielectric constant and the high-frequency dielectric constant conversion unit 224 is compared with the dielectric constant input through the interface 225, and the voltage of the low-frequency power source 221 is compared. A comparator 226 for outputting a signal for controlling the output, and the output of the comparator 226 is connected to the low-frequency power source 221, and the output of the capacitance meter 222 is Composed of changeover switches 227 to connect in conjunction with the calculation unit 223.
[0013]
Here, the low frequency power source 221 is a power source for controlling the orientation of the liquid crystal cell 214. In the configuration shown in FIG. 1, the low frequency power source 221 is also used as a power source for measuring the capacitance. It has become. In addition, as shown in FIG. 1, the liquid crystal cell 214 may be directly connected instead of being connected to the liquid crystal cell 214 via the capacitance meter 222.
[0014]
In the configuration shown in FIG. 1, the low frequency power source 221 and the capacitance meter 222 are connected to the liquid crystal cell 214 alone, but only the low frequency power source 221 is provided for each liquid crystal cell 214. The total 222 may be switched by a changeover switch and used in common. In FIG. 1, only a configuration in which a pair of low-frequency power source 221 and a capacitance meter 222 is connected to the liquid crystal cell 214 is shown as a representative, and the low-frequency power source 221 and the capacitance meter 222 connected to other liquid crystal cells 214 are omitted. Showed.
[0015]
Hereinafter, the properties of the liquid crystal constituting the liquid crystal layer 213 will be described. As conceptually shown in FIG. 2, the liquid crystal molecules generally have an elongated shape, and the dielectric constant ε1 in the major axis direction of the liquid crystal molecules is different from the dielectric constant ε2 in the minor axis direction (this fact) Is called anisotropy.) When a control voltage is applied to the liquid crystal, according to the height of the control voltage, the liquid crystal molecules try to align so that the major axis direction of the liquid crystal molecules is parallel to the direction of the electric field generated by the applied control voltage.
[0016]
Here, the applied control voltage may be a direct current or a low frequency alternating current of about 1 kHz, for example. In addition, the liquid crystal cell 214 of the radio wave lens is pre-aligned so that the major axis direction of the liquid crystal molecules is parallel to the electrode surface as shown in FIG. 3A when no control voltage is applied. It shall be. By doing so, the orientation of the liquid crystal molecules changes as shown in FIG. 3B in accordance with the increase of the control voltage, and when the control voltage becomes a predetermined value or more, the major axis of the liquid crystal molecules changes to FIG. As shown in (c), it is oriented in a direction substantially perpendicular to the electrode surface.
[0017]
That is, in the state shown in FIG. 3A, the dielectric constant of the liquid crystal layer 213 in the direction perpendicular to the electrodes 211 and 212 (the radio wave passing through the radio wave lens is affected by the dielectric constant in this direction) The dielectric constant ε2 in the minor axis direction, and in the state shown in FIG. 3C, the dielectric constant of the liquid crystal layer 213 in the direction perpendicular to the electrodes 211 and 212 is the dielectric constant ε1 in the major axis direction of the liquid crystal molecules. In the state shown in FIG. 3B, the dielectric constant of the liquid crystal layer 213 perpendicular to the electrodes 211 and 212 is an intermediate dielectric constant between the two. Thus, the alignment state of the liquid crystal molecules changes according to the level of the control voltage, and the dielectric constant of the liquid crystal layer changes.
[0018]
Hereinafter, the operation of the radio wave lens control device according to the embodiment of the present invention will be described.
First, the control voltage output from the low frequency power supply 221 is applied to the liquid crystal cell 214 constituting the radio wave lens 210 via the capacitance meter 222. When a control voltage is applied, the liquid crystal molecules in the liquid crystal layer 213 are aligned according to the height of the control voltage, and the dielectric constant of the liquid crystal layer 213 changes. The capacitance meter 222 measures the capacitance of the liquid crystal cell whose dielectric constant has changed according to the control voltage, and outputs information on the capacitance obtained by the measurement to the dielectric constant calculation unit 223.
[0019]
The dielectric constant calculation unit 223 to which the information on the capacitance is input calculates the dielectric constant ε of the liquid crystal layer 213 based on the input information on the capacitance. Here, calculation of the dielectric constant ε of the liquid crystal layer 213 is possible because the structure of the liquid crystal cell is known. For example, when the area of the first electrode 211 is sufficiently larger than the thickness of the liquid crystal layer 213, It can be easily obtained based on the equation (1).
[0020]
ε = dC / 2S (1)
Here, d represents the thickness of the liquid crystal layer 213, S represents the area of the first electrode 211, and C represents the value of the capacitance of the liquid crystal cell measured by the capacitance meter 222.
[0021]
The dielectric constant calculated by the dielectric constant calculation unit 223 is a dielectric constant (low frequency dielectric constant) at an excitation frequency of the low frequency power source 221, and is generally a dielectric constant (high frequency dielectric) in a high frequency band such as a microwave and a millimeter wave. Rate). However, since the dielectric constant of the liquid crystal in each frequency band is uniquely determined by the alignment state of the liquid crystal, in this embodiment, if the low-frequency dielectric constant of the liquid crystal is known, the alignment state can be known, The high frequency dielectric constant can be obtained from the state.
[0022]
The high-frequency dielectric constant conversion unit 224 stores in advance the relationship between the low-frequency dielectric constant and high-frequency dielectric constant of the liquid crystal obtained as described above, and converts the low-frequency dielectric constant into a high-frequency dielectric constant based on this relationship. To do. As a specific example, if the low-frequency dielectric constants in the major axis and minor axis directions are ε1 L and ε2 L , respectively, and the high-frequency dielectric constants in the major axis and minor axis directions are ε1 H and ε2 H , respectively, The obtained high frequency dielectric constant ε H can be obtained using the observed low frequency dielectric constant ε L as shown in the following equation (2).
ε H = ε2 H + (ε L -ε2 L) (ε1 H -ε2 H) / (ε1 L -ε2 L) (2)
[0023]
On the other hand, the dielectric constant of each liquid crystal cell 214 set to control the radio wave lens is input via the interface 225. When the high-frequency dielectric constant is obtained by the conversion and the setting value of the dielectric constant is input via the interface 225, the comparator 226 compares the high-frequency dielectric constant and the setting value of the dielectric constant so that they match. In addition, the voltage value of the low frequency power source 221 is controlled.
[0024]
By performing the above control in real time, the dielectric constant of the liquid crystal cell can be adjusted to a desired size. By performing the same control for each of the other liquid crystal cells, the radio wave lens as a whole can be adjusted to a desired dielectric constant distribution, and the propagation direction of high-frequency electromagnetic waves can be accurately controlled. Is possible.
[0025]
That is, by using this radio wave lens control device 220, the relationship between the control voltage and the dielectric constant of the liquid crystal layer as shown in FIG. 5 is clarified in advance, and the magnitude of the control voltage is determined in consideration of the result. Therefore, the radio wave lens can be easily controlled.
[0026]
Here, in the radio wave lens control device of the present invention, it is necessary to clarify in advance the relationship between the low-frequency dielectric constant and the high-frequency dielectric constant of the liquid crystal. However, since these relationships are invariant with the material constants, they need only be measured once. That is, ε1 L , ε2 L , ε1 H , and ε2 H in the above equation (2) are measured in advance and can be referred to as a table. Further, if the liquid crystal of the same material is used, the value of the liquid crystal layer thickness d and the area S of the first electrode 211 in the above formula (1) is changed and set in the dielectric constant calculation unit 223. Good.
[0027]
On the other hand, in the conventional technology, even when liquid crystal of the same material is used, the control voltage and the high frequency dielectric constant of the liquid crystal are changed every time the structure is changed, such as changing the size of the electrode of the radio wave lens or the thickness of the liquid crystal layer. The relationship had to be measured in advance. Therefore, the complicated measurement described above must be performed every time the structure of the radio wave lens is changed.
[0028]
In this embodiment, the control power supply is a low-frequency power supply, but the frequency of the control power supply is not limited to this, and any power supply that can control the alignment of the liquid crystal may be used. A controllable high frequency power supply can also be used as a control power supply.
Further, the capacitance meter in the present invention means a means capable of measuring the capacitance of the object to be measured. The case where the capacitance of the object to be measured is calculated from the measured values of individual voltmeters and ammeters is also expressed as a capacitance meter in the context of the present invention.
[0029]
As described above, the radio wave lens control device according to the embodiment of the present invention has a control voltage magnitude applied to an electrode and a dielectric constant of a liquid crystal layer, which are conventionally required in radio wave lens control using liquid crystal. It is possible to save the trouble of measuring the relationship in advance.
In addition, it is possible to easily adjust the dielectric constant and control the radio wave lens without being aware of these complicated relationships.
In addition, since the power supply and the capacity meter can be separated from other components, the power supply and the capacity meter are provided in the liquid crystal cell that needs to be measured, and the changeover switch can be switched between electrical connections. Can be measured with good performance.
[0030]
【The invention's effect】
As described above, the present invention can realize a radio wave lens control device that can be easily adjusted to a desired dielectric constant.
[Brief description of the drawings]
FIG. 1 is a diagram showing a block configuration of a radio wave lens control apparatus according to a first embodiment of the present invention.
FIG. 2 is a diagram for explaining anisotropy of dielectric constant of liquid crystal molecules.
FIG. 3 is a diagram for explaining a state of liquid crystal molecules aligned in accordance with an applied voltage.
FIG. 4 is a diagram illustrating a configuration of a radio wave lens and a configuration of a conventional control device that controls a dielectric constant of a liquid crystal in a liquid crystal cell constituting the radio wave lens.
FIG. 5 is a diagram illustrating an example of a relationship between a control voltage applied to a liquid crystal and a relative dielectric constant of the liquid crystal.
[Explanation of symbols]
110, 213 Liquid crystal layer 120, 211 First electrode 130, 212 Second electrode 140 Control power supply 150, 214 Liquid crystal cell 210 Radio lens 220 Radio lens control device 221 Low frequency power source 222 Capacitance meter 223 Dielectric constant calculator 224 High frequency dielectric Rate conversion unit 225 Interface 226 Comparator 227 Changeover switch

Claims (1)

液晶セルに印加する電圧可変の電源と、
前記電源に接続された前記液晶セルの静電容量を測定する容量計と、
前記容量計が測定した静電容量に基づいて前記液晶セルに含まれる液晶の誘電率を算出する誘電率算出部と、
前記誘電率算出部が算出した前記誘電率を所望の周波数における誘電率に換算する高周波誘電率換算部と、
前記液晶の誘電率として設定すべき値を入力させるインタフェースと、
前記高周波誘電率換算部が換算して得られた誘電率を、前記インタフェース経由で入力された誘電率の値に一致させる方向に前記電源の出力電圧の制御を行う比較器とを備えたことを特徴とする電波レンズ制御装置。A voltage variable power source to be applied to the liquid crystal cell;
A capacitance meter that measures the capacitance of the liquid crystal cell connected to the power source;
A dielectric constant calculator that calculates the dielectric constant of the liquid crystal contained in the liquid crystal cell based on the capacitance measured by the capacitance meter;
A high-frequency dielectric constant converter that converts the dielectric constant calculated by the dielectric constant calculator into a dielectric constant at a desired frequency;
An interface for inputting a value to be set as the dielectric constant of the liquid crystal;
A comparator that controls the output voltage of the power source in a direction that matches the dielectric constant obtained by the high-frequency dielectric constant conversion unit with the value of the dielectric constant input via the interface. A radio lens control device.
JP2003197857A 2003-07-16 2003-07-16 Radio wave lens control apparatus Pending JP2005039370A (en)

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Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR101155510B1 (en) * 2010-09-14 2012-06-18 한국과학기술원 Radome-antenna assembly for compensating insertion phase delay of phase array antenna and method for compensating insertion phase delay in using same
US9509179B2 (en) 2011-09-13 2016-11-29 Samsung Electronics Co., Ltd. Wireless electromagnetic receiver and wireless power transfer system
WO2019188830A1 (en) * 2018-03-27 2019-10-03 豊田合成株式会社 Transducer device
CN111416191A (en) * 2020-03-31 2020-07-14 苏治国 Preparation method of broadband phase-adjustable phase shifter based on variable dielectric constant substrate
US11112440B2 (en) * 2018-07-02 2021-09-07 Boe Technology Group Co., Ltd. Measuring device for liquid crystal dielectric constant, measuring apparatus, measuring method

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR101155510B1 (en) * 2010-09-14 2012-06-18 한국과학기술원 Radome-antenna assembly for compensating insertion phase delay of phase array antenna and method for compensating insertion phase delay in using same
US9509179B2 (en) 2011-09-13 2016-11-29 Samsung Electronics Co., Ltd. Wireless electromagnetic receiver and wireless power transfer system
WO2019188830A1 (en) * 2018-03-27 2019-10-03 豊田合成株式会社 Transducer device
JP2019176574A (en) * 2018-03-27 2019-10-10 豊田合成株式会社 Transducer device
CN111903050A (en) * 2018-03-27 2020-11-06 丰田合成株式会社 Transducer arrangement
US11112440B2 (en) * 2018-07-02 2021-09-07 Boe Technology Group Co., Ltd. Measuring device for liquid crystal dielectric constant, measuring apparatus, measuring method
CN111416191A (en) * 2020-03-31 2020-07-14 苏治国 Preparation method of broadband phase-adjustable phase shifter based on variable dielectric constant substrate

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