JP2001237606A - Variable characteristic high frequency transmission line - Google Patents
Variable characteristic high frequency transmission lineInfo
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- JP2001237606A JP2001237606A JP2000048725A JP2000048725A JP2001237606A JP 2001237606 A JP2001237606 A JP 2001237606A JP 2000048725 A JP2000048725 A JP 2000048725A JP 2000048725 A JP2000048725 A JP 2000048725A JP 2001237606 A JP2001237606 A JP 2001237606A
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- Prior art keywords
- liquid crystal
- frequency
- transmission line
- variable
- line
- Prior art date
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Abstract
Description
【０００１】[0001]
【発明の属する技術分野】この発明は、高周波回路部品
に係り、特に、特性を調整できる高周波伝送線路に関す
るものである。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-frequency circuit component, and more particularly to a high-frequency transmission line whose characteristics can be adjusted.
【０００２】[0002]
【従来の技術】ネマチック液晶を利用した可変特性高周
波伝送線路の応用例として、マイクロ波帯可変移相器
が、D. Dolfi, M.Labeyrie, P. Joffre and P. Huignar
d:“Liquid crystal microwave phase shifter, ”Elec
tron. Lett., Vol. 29, No. 10,pp. 926-927 (1993)に
より報告されている。この報告による「液晶可変移相
器」の動作原理を図１図示の構造図に従って説明する。
まず、２枚のセラミクス基板１１，１２に挟まれた部分
（図１図示の二周波駆動用液晶の部分）１３に通常のネ
マチック液晶を封入する。１枚の基板１２にはグランド
面用の金属膜１５を付け、もう１枚の基板１１には導体
線路（金属ライン）１４を付ける。また、両セラミクス
基板１１，１２の液晶に接する部分には、液晶分子に初
期配向を与えるためのポリイミド配向膜１６をつける。
これにより本構造は液晶を誘電体基板と見なしたマイク
ロストリップ線路となる。2. Description of the Related Art As an application example of a variable characteristic high frequency transmission line using a nematic liquid crystal, a microwave band variable phase shifter is disclosed in D. Dolfi, M. Labeyrie, P. Joffre and P. Huignar.
d: “Liquid crystal microwave phase shifter,” Elec
tron. Lett., Vol. 29, No. 10, pp. 926-927 (1993). The operating principle of the "liquid crystal variable phase shifter" based on this report will be described with reference to the structural diagram shown in FIG.
First, a normal nematic liquid crystal is sealed in a portion 13 (a portion of the dual-frequency driving liquid crystal shown in FIG. 1) sandwiched between the two ceramic substrates 11 and 12. One substrate 12 is provided with a ground surface metal film 15, and the other substrate 11 is provided with a conductor line (metal line) 14. Further, a polyimide alignment film 16 for giving initial alignment to liquid crystal molecules is provided on portions of both ceramics substrates 11 and 12 which are in contact with the liquid crystal.
Thus, the present structure becomes a microstrip line in which the liquid crystal is regarded as a dielectric substrate.
【０００３】次に、導体線路とグランド面の間に制御電
圧を加えることにより液晶分子の配向が変化する。液晶
の誘電率には異方性があるため、分子の配向が変化する
とマイクロストリップ線路を伝搬する電磁波に対する誘
電率が変化する。電磁波が長さ１のマイクロストリップ
線路を伝搬するときの伝搬遅延時間にもとづく位相の遅
れφは、Next, by applying a control voltage between the conductor line and the ground plane, the orientation of the liquid crystal molecules changes. Since the dielectric constant of the liquid crystal is anisotropic, when the orientation of the molecule changes, the dielectric constant with respect to the electromagnetic wave propagating through the microstrip line changes. The phase delay φ based on the propagation delay time when an electromagnetic wave propagates through a microstrip line of length 1 is
【数１】 ここで、εeff はマイクロストリップ線路の実効誘電
率、ｆは伝搬する電磁波の周波数、ｃは真空中の光の速
度である。εeff はまた、マイクロストリップ線路を伝
搬する電磁波が受ける液晶の誘電率の関数として表され
る。この結果、導体線路とグランド面の間の制御電圧に
よりマイクロストリップ線路の位相遅れが変化し可変移
相器となる。(Equation 1) Here, ε eff is the effective dielectric constant of the microstrip line, f is the frequency of the propagating electromagnetic wave, and c is the speed of light in a vacuum. ε eff is also expressed as a function of the dielectric constant of the liquid crystal experienced by the electromagnetic wave propagating through the microstrip line. As a result, the phase delay of the microstrip line changes due to the control voltage between the conductor line and the ground plane, and a variable phase shifter is obtained.
【０００４】[0004]
【発明が解決しようとする課題】液晶を用いた可変特性
高周波伝送線路の挿入損を考える。マイクロ波やミリ波
では、線路の特性インピーダンスは一般に５０Ωが使用
されるので、液晶を用いた可変特性高周波伝送線路の特
性インピーダンスも５０Ωとして考える。この条件下
で、伝送線路を構成するマイクロストリップ線路の誘電
体損αd と導体損α c の値を、液晶層の厚さｈを変化さ
せて計算した結果の一例（周波数１０GHz ）を図２に示
す。図より線路の挿入損を小さくするためには、液晶層
の厚さｈを厚くし導体線路幅を広くするなどして、マイ
クロストリップ線路の導体損αc を小さくする必要のあ
ることがわかる。SUMMARY OF THE INVENTION Variable characteristics using liquid crystal
Consider the insertion loss of a high-frequency transmission line. Microwave and millimeter wave
Then, the characteristic impedance of the line is generally 50Ω
Characteristics of the variable-characteristic high-frequency transmission line using liquid crystal.
The impedance is also assumed to be 50Ω. Under this condition
The dielectric of the microstrip line that constitutes the transmission line
Body loss αd And conductor loss α c Is changed by changing the thickness h of the liquid crystal layer.
Fig. 2 shows an example of the calculation result (frequency 10 GHz).
You. As shown in the figure, to reduce the line insertion loss, the liquid crystal layer
To increase the thickness h of the conductor and the width of the conductor line.
Cross-trip line conductor loss αc Need to be smaller
You can see that
【０００５】ところが、液晶を用いた可変特性高周波伝
送線路の液晶材料として通常のネマチック液晶を用いる
と、液晶分子の配向の均一性を保つために、液晶層の厚
さを一般に１００μm 程度以下にしなければならない。
液晶を用いた可変特性高周波伝送線路は液晶分子の配向
変化による誘電率の変化を動作原理としているため、配
向の均一性の確保は不可欠であり、液晶層を厚く、従っ
て導体損を小さくすることは困難であった。実際、前出
のD. Dolfiらの報告では、ｈ＝５０μm としている。従
って、従来の可変特性高周波伝送線路では、その線路長
を長くすると大きな挿入損失は避けられず、挿入損失の
低減が課題であった。However, when a normal nematic liquid crystal is used as the liquid crystal material of the variable characteristic high-frequency transmission line using liquid crystal, the thickness of the liquid crystal layer must be generally less than about 100 μm in order to maintain the uniformity of the alignment of the liquid crystal molecules. Must.
Variable-characteristic high-frequency transmission lines using liquid crystals are based on the principle of change in dielectric constant due to changes in the orientation of liquid crystal molecules, so it is essential to ensure uniformity of orientation.Thickness of the liquid crystal layer and therefore reduction of conductor loss are essential. Was difficult. In fact, the above-mentioned report by D. Dolfi et al. Sets h = 50 μm. Therefore, in the conventional variable-characteristic high-frequency transmission line, if the line length is increased, a large insertion loss is unavoidable, and reduction of the insertion loss has been a problem.
【０００６】一方、通常のネマチック液晶を用いたデバ
イスにおいて、液晶分子の配向の応答時間は、液晶層の
厚さの２乗に比例することが知られている（E. Jakeman
andE. P. Raynes, Phys. Lett., 39A, 1992)。液晶を
用いた可変特性高周波伝送線路は、液晶分子の配向変化
による誘電率の変化を動作原理としているため、導体損
を小さくするために液晶層を厚くすると伝送特性調整の
応答時間が遅くなり、例えば可変移相器への応用を考え
るとその移相制御性が悪くなるという問題が生じる。Do
lfi らによれば、このために液晶層の厚さを一般に１０
０μm 程度以下にしなければならないとしており、実
際、前述の報告ではｈ＝５０μm としている。従って従
来の可変特性高周波伝送線路では、応答時間と挿入損は
トレードオフとなり両者同時の改善は難しかった。On the other hand, in a device using a normal nematic liquid crystal, it is known that the response time of the alignment of liquid crystal molecules is proportional to the square of the thickness of the liquid crystal layer (E. Jakeman).
andE. P. Raynes, Phys. Lett., 39A, 1992). Variable-characteristic high-frequency transmission lines using liquid crystal are based on the principle of change in dielectric constant due to the change in the orientation of liquid crystal molecules.Thus, if the liquid crystal layer is thickened to reduce conductor loss, the response time for transmission characteristic adjustment will be slowed down. For example, when applied to a variable phase shifter, a problem arises in that the phase shift controllability is deteriorated. Do
According to lfi et al., the thickness of the liquid crystal layer is generally reduced to 10
It must be less than about 0 μm, and in fact, in the above-mentioned report, h = 50 μm. Therefore, in the conventional variable-characteristic high-frequency transmission line, the response time and the insertion loss are traded off, and it is difficult to improve both at the same time.
【０００７】そこで本発明の目的は、従来のこの種課題
を解決し、挿入損失の低減が図れかつ伝送特性調整の応
答時間の短縮の図れる可変特性高周波伝送線路を提供せ
んとするものである。SUMMARY OF THE INVENTION An object of the present invention is to provide a variable-characteristic high-frequency transmission line that solves the above-mentioned conventional problems and that can reduce insertion loss and shorten response time for adjusting transmission characteristics.
【０００８】[0008]
【課題を解決するための手段】この目的を達成するた
め、可変特性高周波伝送線路の第１の発明は、高周波伝
送線路を構成する誘電体材料として紙、布または繊維に
液晶を含浸させた材料を用いたことを特徴とするもので
ある。In order to achieve this object, a first aspect of the variable characteristic high frequency transmission line is a material in which a liquid crystal is impregnated in paper, cloth or fiber as a dielectric material constituting the high frequency transmission line. Is used.
【０００９】また、第２の発明は、高周波伝送線路を構
成する誘電体材料として二周波駆動用液晶を用い、該二
周波駆動用液晶のクロスオーバ周波数をはさむ複数の周
波数の電圧で構成した信号により駆動するよう構成した
ことを特徴とするものである。A second invention uses a dual-frequency driving liquid crystal as a dielectric material constituting a high-frequency transmission line, and uses a signal composed of a plurality of voltages including a crossover frequency of the dual-frequency driving liquid crystal. , And is configured to be driven.
【００１０】[0010]
【発明の実施の形態】図２図示の特性から明らかなよう
に、液晶を用いた可変特性高周波伝送線路の挿入損失の
低減を図るための一つの方法として液晶層を厚くすれば
よい。しかし、従来の液晶層では、液晶分子の配向の均
一性の制限から、液晶層の厚さを厚くすることができな
かった。DESCRIPTION OF THE PREFERRED EMBODIMENTS As is clear from the characteristics shown in FIG. 2, one method for reducing the insertion loss of a variable characteristic high-frequency transmission line using liquid crystal is to increase the thickness of a liquid crystal layer. However, in the conventional liquid crystal layer, the thickness of the liquid crystal layer cannot be increased due to the limitation of the uniformity of the alignment of the liquid crystal molecules.
【００１１】一方、繊維含浸液晶では、液晶を紙、布あ
るいは繊維などに含浸させることにより、液晶分子の配
向はこれら繊維の界面に影響されて均一性を保つことが
できる（応答性がよくなる）。従って、例えば、液晶を
含浸させた紙を複数枚重ねるなどの方法により液晶層の
厚さを厚くしても、配向の均一性を損なうことはない。
そこで、繊維含浸液晶を液晶を用いた可変特性高周波伝
送線路へ利用すれば液晶層の厚さを厚くすることが可能
となり、線路の導体損を減らしても挿入損失を低減でき
る。また、繊維の並び方（方向性）が一方向にそろった
紙や繊維を用いることにより、液晶分子の配向をより均
一に保つことができるようになる（応答性がよりよくな
る）。On the other hand, in a fiber-impregnated liquid crystal, by impregnating the liquid crystal with paper, cloth, fiber, or the like, the orientation of liquid crystal molecules can be maintained uniform by being affected by the interface between these fibers (response is improved). . Therefore, even if the thickness of the liquid crystal layer is increased by, for example, stacking a plurality of sheets of liquid crystal-impregnated paper, the uniformity of alignment is not impaired.
Therefore, if the fiber-impregnated liquid crystal is used for the variable characteristic high frequency transmission line using the liquid crystal, the thickness of the liquid crystal layer can be increased, and the insertion loss can be reduced even if the conductor loss of the line is reduced. In addition, by using paper or fibers in which fibers are arranged in one direction (directionality), the orientation of liquid crystal molecules can be kept more uniform (response is better).
【００１２】次に、液晶を用いた可変特性高周波伝送線
路の特性調整の応答時間短縮を図る手段として、二周波
駆動用液晶を誘電体材料として用い、この液晶のクロス
オーバ周波数をはさむ二つの周波数の電圧で構成した信
号を制御信号として用いることを考える。Next, as a means for shortening the response time of the characteristic adjustment of the variable characteristic high-frequency transmission line using the liquid crystal, a two-frequency driving liquid crystal is used as a dielectric material, and two frequencies including a crossover frequency of the liquid crystal are used. Let us consider using a signal composed of these voltages as a control signal.
【００１３】液晶分子は、一般に細長い形をしており、
分子の長軸方向の誘電率をε//、短軸方向の誘電率をε
⊥とすれば、ε//とε⊥の値が異なる異方性を示す。こ
の様な液晶に制御電圧を加えると、液晶分子の配向は、
誘電率の大きい軸が制御電圧と平行になるように変化す
る。通常のネマチック液晶ではε//＞ε⊥であり、電圧
を加えると液晶分子の長軸が電圧と平行になるように配
向する。ところが、二周波駆動用液晶では、誘電率の異
方性に印加電圧の周波数依存性があり、制御電圧の周波
数の低い領域ではε//＞ε⊥であるが、周波数を高くし
ていくとε//＝ε⊥となり（このときの周波数をクロス
オーバ周波数と呼ぶ）、さらに高い周波数ではε//＜ε
⊥となる。従って液晶は、クロスオーバ周波数より低い
周波数の電圧を加えるとその長軸が電圧と平行になるよ
うに配向し、高い周波数の電圧を加えると短軸が平行
（即ち長軸が電圧と直交）になるように配向する。Liquid crystal molecules generally have an elongated shape,
The dielectric constant in the major axis direction of the molecule is ε //, and the dielectric constant in the minor axis direction is ε
⊥ indicates anisotropy in which the values of ε // and ε⊥ are different. When a control voltage is applied to such a liquid crystal, the orientation of the liquid crystal molecules becomes
The axis having a large dielectric constant changes so as to be parallel to the control voltage. In a normal nematic liquid crystal, ε /> εε, and when a voltage is applied, the liquid crystal molecules are oriented so that the major axis is parallel to the voltage. However, in the dual-frequency driving liquid crystal, the anisotropy of the dielectric constant has a frequency dependence of the applied voltage, and in a region where the frequency of the control voltage is low, ε //> ε⊥. ε // = ε⊥ (the frequency at this time is called the crossover frequency), and at higher frequencies ε // <ε
It becomes ⊥. Therefore, the liquid crystal is oriented so that its major axis becomes parallel to the voltage when a voltage having a frequency lower than the crossover frequency is applied, and its minor axis becomes parallel (that is, its major axis is orthogonal to the voltage) when a high frequency voltage is applied. Orientation.
【００１４】ただし、伝送線路を伝搬するような高周波
帯では、二周波駆動用液晶においても誘電率の周波数依
存性はほとんどなく、通常のネマチック液晶と同じくε
//＞ε⊥を示す。従って、高周波伝送線路の誘電体とし
ての振る舞いは通常のネマチック液晶と同じである。However, in a high-frequency band that propagates through a transmission line, even a two-frequency driving liquid crystal has almost no frequency dependence of the dielectric constant, and ε, like a normal nematic liquid crystal.
//> ε⊥. Therefore, the behavior of the high-frequency transmission line as a dielectric is the same as that of a normal nematic liquid crystal.
【００１５】一般に液晶分子の配向はこのような制御電
圧の他に、ガラス基板などに設けられた配向膜に起因す
る力によって制御される。従来の技術では、一般的なネ
マチック液晶を用いており、液晶をマイクロ波電界と垂
直な方向へ配向させる力は、制御電圧による力は利用で
きず配向膜の力だけである。このため、制御電圧を除去
して垂直方向へ配向するときには、その応答時間が遅く
なるといった問題があった。そこで、本発明では二周波
駆動用液晶とクロスオーバ周波数をはさむ複数の周波数
の電圧で構成した信号を制御電圧に用いており、かくす
れば制御電圧で液晶を垂直方向へ配向させる大きな力を
与えることができるので、応答時間の改善が可能とな
る。In general, the alignment of liquid crystal molecules is controlled by a force caused by an alignment film provided on a glass substrate or the like, in addition to the control voltage. In the prior art, a general nematic liquid crystal is used, and the force for aligning the liquid crystal in the direction perpendicular to the microwave electric field cannot be used by the control voltage, but is only the force of the alignment film. For this reason, there is a problem that the response time is delayed when the control voltage is removed and the alignment is performed in the vertical direction. Therefore, in the present invention, a signal composed of a voltage of a plurality of frequencies sandwiching the crossover frequency with the two-frequency driving liquid crystal is used as the control voltage, and thus the control voltage gives a large force to orient the liquid crystal in the vertical direction. Therefore, the response time can be improved.
【００１６】さらに上述の構成で挿入損を低減をするこ
とを考える。図２から明らかなように、液晶を用いた可
変特性高周波伝送線路の挿入損を低減するための一つの
方法として、液晶層を厚くすればよいことがあった。し
かし、従来のような通常のネマチック液晶では、配向の
応答時間の制約から、液晶層を厚くすることができなか
った。一方、二周波駆動用液晶を用い、この液晶のクロ
スオーバ周波数をはさむ二つの周波数の電圧で構成した
信号を制御信号として用いれば、液晶層をある程度厚く
しても配向の応答時間が遅くならないことがわかった。
そこで、二周波駆動用液晶を液晶を用いた可変特性高周
波伝送線路に応用し、この液晶のクロスオーバ周波数を
はさむ二つの周波数の電圧で構成した信号を制御信号と
して用いて液晶層を厚くすることが可能となり、線路の
導体損を減らして挿入損を低減できることとなった。Further, it is considered that the insertion loss is reduced by the above configuration. As is apparent from FIG. 2, as one method for reducing the insertion loss of the variable-characteristic high-frequency transmission line using liquid crystal, the liquid crystal layer may be thickened. However, in a conventional nematic liquid crystal as in the past, the liquid crystal layer could not be thickened due to the restriction of the response time of the alignment. On the other hand, if a two-frequency driving liquid crystal is used and a signal composed of two frequency voltages sandwiching the crossover frequency of the liquid crystal is used as a control signal, the response time of the alignment will not be delayed even if the liquid crystal layer is made somewhat thick. I understood.
Therefore, the dual-frequency driving liquid crystal is applied to a variable-characteristic high-frequency transmission line using liquid crystal, and the liquid crystal layer is made thicker by using a signal composed of two frequency voltages sandwiching the crossover frequency of the liquid crystal as a control signal. It became possible to reduce the conductor loss of the line and the insertion loss.
【００１７】[0017]
【実施例】以下、添付図面を参照し実施例により本発明
の実施の形態をさらに詳細に説明する。第１の実施例と
して本明細書記載第１の発明に係る繊維含浸液晶を用い
た可変特性高周波伝送線路の応用例としての可変移相器
の構造図を図１を使用して説明する。第１の発明に係る
可変移相器には２枚のセラミクス基板１１，１２と繊維
含浸液晶１３と導体線路１４とグランド面１５と制御電
源１７とを含む。繊維含浸液晶１３は、液晶を紙、布あ
るいは繊維などへ含浸した構造を有する。高周波信号１
７は、２枚のセラミクス基板１１，１２の間に封入され
た繊維含浸液晶１３を誘電体基板として導体線路１４と
グランド面１５で構成するマイクロストリップ線路を伝
搬する。制御電源１７は本発明に係る可変移相器の移相
量を調整する制御信号により調整された直流、あるいは
低周波電圧信号を、導体線路１３とグランド面１４の間
に印加する。この電圧に応じて繊維含浸液晶１３の誘電
率が変化し可変移相器の移相量が変化する。繊維含浸液
晶１３の厚さｈは、可変移相器の挿入損失が小さくなる
ような厚さとして、例えば、２００μm から６００μm
程度に設定すれば、導体損を誘電損より小さくすること
が可能となる。Embodiments of the present invention will be described below in more detail with reference to the accompanying drawings. As a first embodiment, a structural diagram of a variable phase shifter as an application example of a variable characteristic high-frequency transmission line using a fiber-impregnated liquid crystal according to the first invention described in the present specification will be described with reference to FIG. The variable phase shifter according to the first invention includes two ceramic substrates 11 and 12, a fiber-impregnated liquid crystal 13, a conductor line 14, a ground plane 15, and a control power supply 17. The fiber-impregnated liquid crystal 13 has a structure in which liquid crystal is impregnated into paper, cloth, fiber, or the like. High frequency signal 1
7 propagates a microstrip line composed of a conductor line 14 and a ground plane 15 using a fiber-impregnated liquid crystal 13 sealed between two ceramic substrates 11 and 12 as a dielectric substrate. The control power supply 17 applies a DC or low frequency voltage signal adjusted by a control signal for adjusting a phase shift amount of the variable phase shifter according to the present invention between the conductor line 13 and the ground plane 14. The dielectric constant of the fiber-impregnated liquid crystal 13 changes according to this voltage, and the phase shift amount of the variable phase shifter changes. The thickness h of the fiber-impregnated liquid crystal 13 is, for example, from 200 μm to 600 μm so as to reduce the insertion loss of the variable phase shifter.
If it is set to a degree, the conductor loss can be made smaller than the dielectric loss.
【００１８】繊維含浸液晶１３で使用される液晶は、高
周波に対して誘電率異方性を有し、細長い液晶分子の長
軸方向の誘電率は、短軸方向のものに比べて高い。その
誘電率異方性は、可能な限り大きい方が位相を大きく制
御できるため、誘電率異方性が大きなネマティック液
晶、コレステリック液晶、スメクティック液晶またはこ
れら液晶の混合液晶を選択して用いることができる。た
だし、高速性を得るには、低粘性かつ高弾性のネマティ
ック液晶が適している。特に、屈折率異方性の大きなシ
アノビフェニル系、ターフェニル系、ピリジン系、ピリ
ミジン系およびトラン系のネマティック液晶が最適であ
る。一方、スメクティック液晶を用いる場合には、自発
分極を有して高速応答を示す強誘電性液晶が有用であ
る。また、このような液晶を含浸する繊維としては、高
周波に対する損失が少なく、かつ、より多くの液晶を含
むことのできる材料や構造が有効である。The liquid crystal used in the fiber-impregnated liquid crystal 13 has dielectric anisotropy with respect to a high frequency, and the dielectric constant in the long axis direction of the elongated liquid crystal molecules is higher than that in the short axis direction. Since the larger the dielectric anisotropy is, the larger the phase can be controlled as much as possible, a nematic liquid crystal, a cholesteric liquid crystal, a smectic liquid crystal, or a mixed liquid crystal of these liquid crystals having a large dielectric anisotropy can be selected and used. . However, in order to obtain high speed, a nematic liquid crystal having low viscosity and high elasticity is suitable. In particular, cyanobiphenyl-based, terphenyl-based, pyridine-based, pyrimidine-based and tolan-based nematic liquid crystals having large refractive index anisotropy are most suitable. On the other hand, when a smectic liquid crystal is used, a ferroelectric liquid crystal having spontaneous polarization and exhibiting a high-speed response is useful. In addition, as a fiber impregnating such a liquid crystal, a material or a structure that has a small loss with respect to a high frequency and can include more liquid crystal is effective.
【００１９】なお、この第１の実施例では、可変移相器
に用いる伝送線路の形態としてマイクロストリップ線路
を例示したが、本発明における高周波信号の伝送線路は
マイクロストリップ線路だけに制限されるものではな
く、同軸線路、コプレーナ線路、ストリップ線路などの
誘電体を使った高周波信号用伝送線路すべてに応用可能
である。In the first embodiment, a microstrip line is exemplified as a form of the transmission line used for the variable phase shifter. However, the transmission line of the high-frequency signal in the present invention is limited to only the microstrip line. Instead, the present invention can be applied to all transmission lines for high-frequency signals using a dielectric such as a coaxial line, a coplanar line, and a strip line.
【００２０】次に第２の実施例として本明細書記載第１
の発明に係る繊維含浸液晶を同軸線路へ用いる構造を図
３に示す。繊維含浸液晶３１を中心導体３２にロール状
に巻き付け３４、さらにその上に外部導体３３をつける
ことにより、繊維含浸液晶を誘電体とした同軸線路を構
成することができる。制御電源３５を中心導体３２と外
部導体３３に接続してその電圧を変化させることによ
り、同軸線路の伝送特性を調整することができる。同軸
線路の場合、通常のネマチック液晶を同軸線路に封入す
れば、可変特性高周波伝送線路が実現できると考えられ
る。しかし、 （イ）外部導体内面や中心導体表面に配向処理を施すこ
とが難しい。 （ロ）液晶部分の厚さ（即ち、中心導体と外部導体の隙
間）が厚く、液晶分子の配向の均一性が保てない。 の問題から、その実現は困難であった。繊維含浸液晶を
図３のように用いれば、上記問題は解決され、同軸型の
可変特性高周波伝送線路が実現できる。Next, as a second embodiment, the first embodiment described in the present specification will be described.
FIG. 3 shows a structure in which the fiber-impregnated liquid crystal according to the invention is used for a coaxial line. By winding the fiber-impregnated liquid crystal 31 around the central conductor 32 in a roll shape and further attaching the external conductor 33 thereon, a coaxial line using the fiber-impregnated liquid crystal as a dielectric can be formed. By connecting the control power supply 35 to the center conductor 32 and the outer conductor 33 and changing the voltage, the transmission characteristics of the coaxial line can be adjusted. In the case of a coaxial line, if a normal nematic liquid crystal is sealed in the coaxial line, it is considered that a variable characteristic high frequency transmission line can be realized. However, (a) it is difficult to perform orientation treatment on the inner surface of the outer conductor and the surface of the center conductor. (B) The thickness of the liquid crystal portion (i.e., the gap between the center conductor and the outer conductor) is large, and the uniformity of the alignment of the liquid crystal molecules cannot be maintained. The problem was difficult to achieve. If the fiber-impregnated liquid crystal is used as shown in FIG. 3, the above problem is solved and a coaxial variable characteristic high frequency transmission line can be realized.
【００２１】さらに第３の実施例として本明細書記載第
２の発明に係る二周波駆動用液晶を用いた可変特性高周
波伝送線路の応用例としての可変移相器の構造図を再び
図１を使用して説明する。第２の発明に係る可変移相器
には、２枚のセラミクス基板１１，１２と二周波駆動用
液晶１３と導体線路１４とグランド面１５と配向膜１６
と制御電源１７とを含む。高周波信号１８は２枚のセラ
ミクス基板１１，１２の間に封入された二周波駆動用液
晶１３を誘電体基板として導体線路１４とグランド面１
５で構成するマイクロストリップ線路を伝搬する。制御
電源１７はこの可変移相器の移相量を調整する制御電圧
を、導体線路１４とグランド面１５の間に印加する。こ
の制御電圧の波形の一例を図４に示す。二周波駆動用液
晶１３のクロスオーバ周波数より低い周波数の電圧とて
直流（図４（ａ））、高い周波数の電圧として数kHz の
正弦波（図４（ｂ））とし、この２つの電圧を加えたも
のを制御電圧（図４（ｃ））とする。FIG. 1 is a structural diagram of a variable phase shifter as an application example of a variable characteristic high-frequency transmission line using a dual-frequency driving liquid crystal according to a second embodiment of the present invention as a third embodiment. It is explained using. The variable phase shifter according to the second invention has two ceramic substrates 11, 12, two-frequency driving liquid crystal 13, conductor line 14, ground plane 15, and alignment film 16.
And a control power supply 17. The high-frequency signal 18 is formed by using the two-frequency driving liquid crystal 13 sealed between the two ceramics substrates 11 and 12 as a dielectric substrate and the conductor line 14 and the ground plane 1.
5 propagates through the microstrip line. The control power supply 17 applies a control voltage for adjusting the phase shift amount of the variable phase shifter between the conductor line 14 and the ground plane 15. FIG. 4 shows an example of the waveform of the control voltage. A voltage having a frequency lower than the crossover frequency of the two-frequency driving liquid crystal 13 is a direct current (FIG. 4A), and a high frequency voltage is a sine wave of several kHz (FIG. 4B). The added voltage is used as a control voltage (FIG. 4C).
【００２２】直流電圧は二周波駆動用液晶１３の配向が
高周波電界と平行になるための力を発生させ、また高い
周波数の電圧は配向が高周波電界に垂直となるための力
を発生させる。そこでこの第２の発明では、図４（ｄ）
に示すように二周波駆動用液晶１３は、この二種類の電
圧４２による力および配向膜による力がバランスした方
向に液晶分子４１が配向し、これに応じて高周波帯にお
ける誘電率が変化して第２の発明の可変移相器の移相量
が変化する。二周波駆動用液晶１３の厚さｈを例えば２
００μm から６００μm 程度に設定しても、本可変移相
器の移相の応答時間を実用的に問題とならない程度に保
ちつつ、挿入損を小さくすることができる。The DC voltage generates a force for the orientation of the two-frequency driving liquid crystal 13 to be parallel to the high frequency electric field, and the high frequency voltage generates a force for the orientation to be perpendicular to the high frequency electric field. Therefore, in the second invention, FIG.
As shown in (2), in the dual-frequency driving liquid crystal 13, the liquid crystal molecules 41 are oriented in a direction in which the force of the two types of voltage 42 and the force of the alignment film are balanced, and the dielectric constant in the high frequency band changes accordingly. The phase shift amount of the variable phase shifter according to the second invention changes. The thickness h of the two-frequency driving liquid crystal 13 is set to, for example, 2
Even if it is set to about 00 μm to 600 μm, the insertion loss can be reduced while maintaining the phase shift response time of the variable phase shifter to a level that does not cause a practical problem.
【００２３】二周波駆動用液晶１３で使用される液晶層
の構造は、該液晶のみから構成される液晶層のみなら
ず、該液晶を樹脂中に分散させた液晶樹脂複合体、ある
いは、繊維などに該液晶を含浸させた繊維含浸液晶など
を利用した構造も有効である。The structure of the liquid crystal layer used in the dual-frequency driving liquid crystal 13 is not only a liquid crystal layer composed of the liquid crystal alone, but also a liquid crystal resin composite in which the liquid crystal is dispersed in a resin, a fiber, or the like. A structure using a fiber-impregnated liquid crystal impregnated with the liquid crystal is also effective.
【００２４】なお、この第３の実施例では、可変移相器
に用いる伝送線路の形態としてマイクロストリップ線路
を例示したが、本発明における高周波信号の伝送線路は
マイクロストリップ線路だけに制限されるものではな
く、同軸線路、コプレーナ線路、ストリップ線路などの
高周波信号の伝搬媒体として誘電体を使った伝送線路す
べてに応用可能である。In the third embodiment, a microstrip line has been exemplified as a form of the transmission line used for the variable phase shifter. However, the transmission line of the high-frequency signal in the present invention is limited to only the microstrip line. Instead, the present invention is applicable to all transmission lines using a dielectric as a propagation medium for high-frequency signals, such as coaxial lines, coplanar lines, and strip lines.
【００２５】また、本発明における制御信号は、本実施
例で例示した直流電圧とクロスオーバ周波数より高い周
波数の電圧を加算した信号に限らず、クロスオーバ周波
数をはさむ複数の周波数の電圧を切り替えた信号、クロ
スオーバ周波数をはさんで周波数変調した信号など、ク
ロスオーバ周波数をはさむ複数の周波数の電圧を組み合
わせて構成される各種の信号が適用可能である。The control signal according to the present invention is not limited to a signal obtained by adding the DC voltage exemplified in the present embodiment and a voltage having a frequency higher than the crossover frequency, and switches a voltage having a plurality of frequencies including the crossover frequency. Various signals, such as a signal and a signal that is frequency-modulated with a crossover frequency interposed therebetween, configured by combining voltages of a plurality of frequencies sandwiching the crossover frequency are applicable.
【００２６】[0026]
【発明の効果】図２より、液晶層の厚さを増やすことに
よる可変移相器の挿入損の変化のうち、特にその変化の
大きな導体損を見積もってみる。従来の方法による可変
移相器の導体損は、液晶層の厚さが５０μm であるから
３１dB／ｍであった。本発明による可変移相器では、液
晶層の厚さを例えば４００μm とすることができるの
で、導体損を４．５dB／ｍと設計することができる。従
って、本発明により、可変移相器の導体損を２６dB／ｍ
減らすことができる。From FIG. 2, among the changes in the insertion loss of the variable phase shifter due to the increase in the thickness of the liquid crystal layer, the conductor loss, which is particularly large, will be estimated. The conductor loss of the variable phase shifter according to the conventional method was 31 dB / m because the thickness of the liquid crystal layer was 50 μm. In the variable phase shifter according to the present invention, the thickness of the liquid crystal layer can be set to, for example, 400 μm, so that the conductor loss can be designed to be 4.5 dB / m. Therefore, according to the present invention, the conductor loss of the variable phase shifter is set to 26 dB / m.
Can be reduced.
【００２７】また本発明による可変移相器の応用例とし
てのフェーズドアレーアンテナを考えてみる。従来技術
による液晶層の薄い（例えば、５０μm ）移相器のよう
に損失が大きいと、その損失を補償するための高周波増
幅器を追加したり、あるいは、より増幅度の大きな高周
波増幅器を使用することになる。本発明の可変移相器を
利用すれば、その分高周波増幅器を簡略化でき経済的効
果も大きい。Consider a phased array antenna as an application example of the variable phase shifter according to the present invention. If the loss is large as in the prior art phase shifter having a thin liquid crystal layer (for example, 50 μm), a high frequency amplifier for compensating for the loss should be added or a high frequency amplifier having a higher amplification should be used. become. If the variable phase shifter of the present invention is used, the high-frequency amplifier can be simplified by that much, and the economical effect is large.
【図１】 本発明に係る可変特性高周波伝送線路の構造
を示す図。FIG. 1 is a diagram showing a structure of a variable characteristic high frequency transmission line according to the present invention.
【図２】 液晶可変移相器の液晶厚さと挿入損（誘電
損、導体損）の関係の一例を計算した図。FIG. 2 is a diagram illustrating an example of the relationship between the liquid crystal thickness and the insertion loss (dielectric loss, conductor loss) of the liquid crystal variable phase shifter.
【図３】 本発明第２の実施例の同軸型可変特性高周波
伝送線路の構造図。FIG. 3 is a structural diagram of a coaxial variable characteristic high frequency transmission line according to a second embodiment of the present invention.
【図４】 本発明第３の実施例の可変特性高周波伝送線
路の制御電圧波形と液晶分子配向の状態を説明する図。FIG. 4 is a diagram illustrating a control voltage waveform and a state of liquid crystal molecular alignment of a variable characteristic high-frequency transmission line according to a third embodiment of the present invention.
11，12 セラミクス基板 13 二周波駆動用液晶 14 導体線路（金属ライン） 15 グランド面（金属膜） 16 配向膜 17 制御電源 18 高周波信号 31 繊維含浸液晶 32 中心導体 33 外部導体 34 ロール状に巻きつけ 35 制御電源 41 液晶分子 42 高周波電界の方向 11, 12 Ceramics substrate 13 Dual frequency drive liquid crystal 14 Conductor line (metal line) 15 Ground plane (metal film) 16 Alignment film 17 Control power supply 18 High frequency signal 31 Fiber impregnated liquid crystal 32 Center conductor 33 External conductor 34 Wrap in roll 35 Control power supply 41 Liquid crystal molecules 42 Direction of high-frequency electric field
───────────────────────────────────────────────────── フロントページの続き (72)発明者 熊田 純二 東京都世田谷区砧１丁目10番11号 日本放 送協会 放送技術研究所内 (72)発明者 藤掛 英夫 東京都世田谷区砧１丁目10番11号 日本放 送協会 放送技術研究所内 Ｆターム(参考） 5J012 GA11 5J014 BA01 CA05 CA42 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Junji Kumada 1-10-11 Kinuta, Setagaya-ku, Tokyo Japan Broadcasting Research Institute (72) Inventor Hideo Fujikake 1-10-11 Kinuta, Setagaya-ku, Tokyo No. Japan Broadcasting Corporation Broadcasting Technology Laboratory F-term (reference) 5J012 GA11 5J014 BA01 CA05 CA42
Claims (2)
して紙、布または繊維に液晶を含浸させた材料を用いた
ことを特徴とする可変特性高周波伝送線路。1. A variable-characteristic high-frequency transmission line using a material in which liquid crystal is impregnated in paper, cloth, or fiber as a dielectric material constituting the high-frequency transmission line.
して二周波駆動用液晶を用い、該二周波駆動用液晶のク
ロスオーバ周波数をはさむ複数の周波数の電圧で構成し
た信号により駆動するよう構成したことを特徴とする可
変特性高周波伝送線路。2. A two-frequency driving liquid crystal is used as a dielectric material constituting a high-frequency transmission line, and driving is performed by a signal composed of a plurality of voltages including a crossover frequency of the two-frequency driving liquid crystal. A variable-characteristic high-frequency transmission line characterized in that:
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| JP2000048725A JP3938267B2 (en) | 2000-02-25 | 2000-02-25 | Variable characteristic high frequency transmission line |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2000048725A JP3938267B2 (en) | 2000-02-25 | 2000-02-25 | Variable characteristic high frequency transmission line |
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| JP2001237606A true JP2001237606A (en) | 2001-08-31 |
| JP3938267B2 JP3938267B2 (en) | 2007-06-27 |
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ID=18570770
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2016086851A1 (en) * | 2014-12-05 | 2016-06-09 | Huawei Technologies Co., Ltd. | System and method for variable microwave phase shifter |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| WO2016086851A1 (en) * | 2014-12-05 | 2016-06-09 | Huawei Technologies Co., Ltd. | System and method for variable microwave phase shifter |
| US9755286B2 (en) | 2014-12-05 | 2017-09-05 | Huawei Technologies Co., Ltd. | System and method for variable microwave phase shifter |
Also Published As
| Publication number | Publication date |
|---|---|
| JP3938267B2 (en) | 2007-06-27 |
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