技术领域technical field
本发明属于微波技术领域使用的磁可调法拉第旋转器，特别涉及新材料石墨烯。The invention belongs to a magnetically adjustable Faraday rotator used in the microwave technology field, and particularly relates to a new material graphene.
背景技术Background technique
在微波系统中，旋转器的作用是将入射波经过旋转器的作用后旋转一个特定的角度，以得到工程上需要的一些特性，旋转器一般用作隔离器的核心部件，其性能会直接影响隔离器的性能优劣。对于有些对反射波极敏感的传输系统，如放大系统，非线性系统等，都需要法拉第旋转器。旋转器的核心部件就是能使电磁波产生角度偏转的材料，因此其材料的选择会直接影响到整个系统的工作性能。In a microwave system, the function of the rotator is to rotate the incident wave by a specific angle after passing through the rotator, so as to obtain some characteristics required in engineering. The rotator is generally used as the core component of the isolator, and its performance will directly affect The performance of the isolator is good or bad. For some transmission systems that are extremely sensitive to reflected waves, such as amplification systems and nonlinear systems, Faraday rotators are required. The core component of the rotator is the material that can deflect the electromagnetic wave, so the selection of the material will directly affect the performance of the entire system.
现今微波频段的旋转器一般以铁氧体等传统材料制作，当有外部磁场加到铁氧体介质上时，其磁导率可以看作是一张量，电磁波入射的时候，将会发生法拉第旋转效应，利用该特性能实现旋转的功能。该种旋转器一般可分为可调旋转器和不可调旋转器两类。不可调旋转器的工程要求较低，实现简单且能满足一定应用要求，此种旋转器的缺点是旋转角度固定无法改变。可调旋转器结构相对较为复杂，但能实现通过改变外部参量来控制旋转角度。传统的基于铁氧体的旋转器需要在圆波导内加载铁氧体棒和四分之一波长板，并外加磁场偏置。在磁场偏置下由于铁氧体的法拉第效应，产生一定的旋转角度。其结构相对比较复杂，体积也相应较大，制作工艺较为繁琐。Nowadays, rotators in the microwave frequency band are generally made of traditional materials such as ferrite. When an external magnetic field is applied to the ferrite medium, its magnetic permeability can be regarded as a tensor. When electromagnetic waves are incident, Faraday Rotation effect, using this feature to realize the function of rotation. This kind of rotator can generally be divided into two types: adjustable rotator and non-adjustable rotator. The non-adjustable rotator has low engineering requirements, is simple to realize and can meet certain application requirements. The disadvantage of this kind of rotator is that the rotation angle is fixed and cannot be changed. The structure of the adjustable rotator is relatively complicated, but it can control the rotation angle by changing the external parameters. Traditional ferrite-based rotators require ferrite rods and quarter-wave plates loaded inside a circular waveguide and biased with an external magnetic field. Under the magnetic field bias, due to the Faraday effect of ferrite, a certain rotation angle is generated. Its structure is relatively complicated, its volume is relatively large, and its manufacturing process is relatively cumbersome.
石墨烯(Graphene)是一种只有一个碳原子厚度的二维材料，由碳原子以sp2杂化轨道组成六角型呈蜂巢晶格。2004年英国科学家Geim和Novoselov等首次通过实验制得，它是目前已知材料中最薄的，并具有出众的物理电子特性。石墨烯在光频段几乎是完全透明的，只吸收2.3％的光；导热系数高达5300W/m·K，高于碳纳米管和金刚石，常温下其电子迁移率超过15000cm2/v·s，又比纳米碳管或硅晶体高，而电阻率只约10-6Ω·cm，比铜或银更低，为目前世上电阻率最小的材料。近年来随着石墨烯制备技术的不断发展，较大尺度的石墨烯薄片已经被成功制作出来，使得石墨烯在微波频段的应用成为可能，石墨烯成为当今微波领域研究的热点之一，以它为基础的一些微波器件具有广泛的应用前景。Graphene is a two-dimensional material with a thickness of only one carbon atom, which consists of carbon atoms with sp2 hybrid orbitals to form a hexagonal honeycomb lattice. In 2004, British scientists Geim and Novoselov made it through experiments for the first time. It is the thinnest known material and has outstanding physical and electronic properties. Graphene is almost completely transparent in the light frequency band, absorbing only 2.3% of light; its thermal conductivity is as high as 5300W/m·K, which is higher than that of carbon nanotubes and diamonds, and its electron mobility exceeds 15000cm2 /v·s at room temperature. It is higher than carbon nanotubes or silicon crystals, and its resistivity is only about 10-6 Ω·cm, which is lower than copper or silver. It is the material with the smallest resistivity in the world. In recent years, with the continuous development of graphene preparation technology, large-scale graphene flakes have been successfully produced, making the application of graphene in the microwave frequency band possible. Graphene has become one of the hotspots in the field of microwave research today. Some microwave devices based on it have broad application prospects.
石墨烯在磁场偏置的情况下，其电导率可认为是各向异性的，在微波信号入射时，会产生法拉第旋转效应，即透射波相对于入射波偏振方向将会发生一定角度的旋转。综合以上特性，使得石墨烯成为制造法拉第旋转器的理想材料。基于石墨烯材料的法拉第旋转器具有结构简单紧凑、体积相对较小、导热性强等优点，同时有利于器件的集成。Under the condition of magnetic field bias, the conductivity of graphene can be considered anisotropic. When the microwave signal is incident, it will produce the Faraday rotation effect, that is, the transmitted wave will rotate at a certain angle relative to the polarization direction of the incident wave. The combination of the above characteristics makes graphene an ideal material for making Faraday rotators. Faraday rotators based on graphene materials have the advantages of simple and compact structure, relatively small volume, strong thermal conductivity, etc., and are also conducive to device integration.
本发明中基于石墨烯的磁可调法拉第旋转器，不仅能够实现旋转角度在一定范围内可调，其旋转方向同样可以控制，而且该种旋转器较传统旋转器具有结构简单紧凑、易于集成和散热性强的优良特性，满足了大功率微波器件小型化的要求，可以广泛地应用于微波系统中。The magnetically adjustable Faraday rotator based on graphene in the present invention can not only realize the adjustable rotation angle within a certain range, but also control the rotation direction. Compared with traditional rotators, this kind of rotator has simple and compact structure, easy integration and The excellent characteristics of strong heat dissipation meet the miniaturization requirements of high-power microwave devices, and can be widely used in microwave systems.
发明内容Contents of the invention
本发明的目的是提供一种应用于微波领域内，能够实现旋转角度在一定范围内可以被精确控制，并且具有较宽的使用频带，控制简单、结构简单紧凑，体积较小和易于集成的磁可调法拉第旋转器。The purpose of the present invention is to provide a magnetic field applied in the microwave field, which can realize the precise control of the rotation angle within a certain range, and has a wide frequency band, simple control, simple and compact structure, small volume and easy integration. Adjustable Faraday rotator.
实现本发明的技术解决方案是：Realize the technical solution of the present invention is:
基于石墨烯的磁可调法拉第旋转器，包括：一个工作频率在微波频段内的圆波导，作为微波信号传输的载体；多层石墨烯模块，在该模块信号产生一定角度的旋转；螺线管模块，利用该模块提供一个方向和信号传播方向相平行的可调静磁场。A magnetically adjustable Faraday rotator based on graphene, including: a circular waveguide with an operating frequency in the microwave frequency band, as a carrier for microwave signal transmission; a multi-layer graphene module, in which the signal generates a certain angle of rotation; a solenoid The module is used to provide an adjustable static magnetic field whose direction is parallel to the direction of signal propagation.
在上述圆波导内垂直于波的传播方向放置多层石墨烯模块，该模块直接紧密的插入到圆波导壁中。多层石墨烯模块是由内部平行排列的多片单层石墨烯片构成的，具有较好的物理特性。在外加一个垂直于石墨烯片的静磁场条件下，微波信号在透射通过石墨烯片时会产生一定角度的偏转。多层石墨烯模块采用多片单层石墨烯平行排列所构成，是因为电磁波在透射通过单层石墨烯片时会发生一定角度的偏转，由于该偏转角度较小不足以满足设计要求，所以采用多层叠加的形式，以达到设计的要求。A multi-layer graphene module is placed in the circular waveguide perpendicular to the propagation direction of the wave, and the module is directly and tightly inserted into the wall of the circular waveguide. The multilayer graphene module is composed of multiple single-layer graphene sheets arranged in parallel inside, and has good physical properties. Under the condition of applying a static magnetic field perpendicular to the graphene sheet, the microwave signal will be deflected at a certain angle when it is transmitted through the graphene sheet. The multi-layer graphene module is composed of multiple sheets of single-layer graphene arranged in parallel, because the electromagnetic wave will deflect at a certain angle when it is transmitted through the single-layer graphene sheet. Since the deflection angle is small enough to meet the design requirements, it is adopted The form of multi-layer superimposition, in order to meet the design requirements.
在上述圆波导的外部套置一个提供偏置磁场的螺线管，螺线管骨架直接套置在圆波导外部，在螺线管骨架上绕有多层的导线构成的线圈。对螺线管供电能够产生磁场，因此可以通过控制电流的强弱来控制外加偏置静磁场的强弱。A solenoid for providing a bias magnetic field is sleeved outside the circular waveguide, the solenoid frame is directly sleeved outside the circular waveguide, and a coil composed of multiple layers of wires is wound on the solenoid frame. Supplying power to the solenoid can generate a magnetic field, so the strength of the applied bias static magnetic field can be controlled by controlling the strength of the current.
所采用的圆波导工作于它的主模TE11模式下，设定相应的工作频段和旋转角度，计算出使用在该频率段下能够单模传输的圆波导尺寸，从而得到石墨烯的尺寸和螺线管的相关参数，通过调节螺线管电流大小就可以调节外加偏置磁场的强度以达到精确控制旋转角，同时可以通过改变螺线管电流的方向来改变偏置磁场的方向，从而改变信号的偏转方向。The circular waveguide used works in its main mode TE11 mode, set the corresponding working frequency band and rotation angle, and calculate the size of the circular waveguide capable of single-mode transmission under this frequency band, so as to obtain the size and The relevant parameters of the solenoid, by adjusting the magnitude of the solenoid current, the strength of the external bias magnetic field can be adjusted to achieve precise control of the rotation angle. At the same time, the direction of the bias magnetic field can be changed by changing the direction of the solenoid current, thereby changing The deflection direction of the signal.
在本发明中能够使电磁波发生偏转的核心材料采用石墨烯取代了传统的铁氧体材料，主要显著的优点：In the present invention, the core material capable of deflecting electromagnetic waves uses graphene instead of the traditional ferrite material. The main notable advantages are:
1、采用新材料石墨烯可以省去了两块四分之一波长板的结构使得结构简单紧凑、体积较小、易于集成；1. The use of new material graphene can save the structure of two quarter-wavelength plates, making the structure simple and compact, small in size and easy to integrate;
2、旋转角度在一定的范围内可以被精确控制，旋转方向也可被控制；2. The rotation angle can be precisely controlled within a certain range, and the rotation direction can also be controlled;
3、控制简单，使用方便。3. Simple control and easy to use.
附图说明Description of drawings
图1为本发明基于石墨烯的磁可调法拉第旋转器的剖视图；Fig. 1 is the sectional view of the magnetic adjustable Faraday rotator based on graphene of the present invention;
图2为电流大小和磁场强弱的关系图；Fig. 2 is the relationship diagram of current magnitude and magnetic field strength;
图3为在中心频率2GHz下旋转角度随磁场强度变化的理论计算图；Figure 3 is a theoretical calculation diagram of the rotation angle changing with the magnetic field strength at a center frequency of 2 GHz;
图4为在中心频率2GHz下幅度特性随磁场强度变化的理论计算图；Fig. 4 is a theoretical calculation diagram of amplitude characteristics changing with magnetic field strength at a center frequency of 2 GHz;
图5为在磁场强度为0.18T时旋转角度随频率变化曲线。Fig. 5 is a curve of rotation angle changing with frequency when the magnetic field strength is 0.18T.
以上图片中含有：The picture above contains:
1：圆波导；2：多层石墨烯模块；2a：单层石墨烯3：螺线管；3a：螺线管骨架；3b：线圈。1: circular waveguide; 2: multilayer graphene module; 2a: single layer graphene; 3: solenoid; 3a: solenoid skeleton; 3b: coil.
具体实施方式Detailed ways
为使本发明实现的技术手段、创作特征、达成目的与功效易于明白了解，下面结合具体实施方式，进一步阐明本发明。In order to make the technical means, creative features, goals and effects achieved by the present invention easy to understand, the present invention will be further elucidated below in conjunction with specific embodiments.
具体实施：Specific implementation:
本发明实例工作频率设置为1.8GHz-2.2GHz，工作模式为在圆波导内传播的主模TE11模式，其电场方向和波传播方向垂直，在波的传播方向无电场分量。The working frequency of the example of the present invention is set to 1.8GHz-2.2GHz, and the working mode is the main mode TE11 mode propagating in the circular waveguide. The electric field direction is perpendicular to the wave propagation direction, and there is no electric field component in the wave propagation direction.
本发明实例结构如图1所示，尺寸单位都为毫米(mm)。主要由圆波导1、多层石墨烯模块和螺线管模块构成，其中波导1为圆波导，内圆直径为114.58mm，外圆直径为121.20mm，长度为200mm。The structure of the example of the present invention is shown in Figure 1, and the unit of size is millimeter (mm). It is mainly composed of a circular waveguide 1, a multilayer graphene module and a solenoid module, wherein the waveguide 1 is a circular waveguide with an inner diameter of 114.58mm, an outer diameter of 121.20mm, and a length of 200mm.
在圆波导的内部中心处，垂直于波的传播方向，放置了多层石墨烯模块。该模块由9片单层石墨烯片所构成，其中每片间隔3mm平行放置。放置顺序如下：在波导中心处放置1片，左右两端分别放置4片，这9片石墨烯片都直接内嵌于圆波导壁中。At the inner center of the circular waveguide, perpendicular to the propagation direction of the wave, a multilayer graphene module is placed. The module is composed of 9 single-layer graphene sheets, each of which is placed in parallel at an interval of 3mm. The order of placement is as follows: one graphene sheet is placed at the center of the waveguide, and four graphene sheets are placed at the left and right ends respectively. These nine graphene sheets are directly embedded in the circular waveguide wall.
在圆波导的外部为螺线管模块。螺线管模块由螺线管骨架和绕在螺线管骨架上的2.5平方毫米铜导线形成的线圈组成，铜导线能够承受的最大电流为20A，能够满足本设计的最大磁场强度要求。螺线管骨架和圆波导精密粘合，以得到较好的机械特性，在螺线管骨架上面密绕2500匝左右的铜导线。On the outside of the circular waveguide is the solenoid module. The solenoid module is composed of a solenoid frame and a coil formed by a 2.5mm2 copper wire wound on the solenoid frame. The copper wire can withstand a maximum current of 20A, which can meet the maximum magnetic field strength requirement of this design. The solenoid frame and the circular waveguide are precisely bonded to obtain better mechanical properties, and about 2500 turns of copper wire are tightly wound on the solenoid frame.
本发明的工作原理如下：The working principle of the present invention is as follows:
本发明的圆波导在长度较短的情况下可以近似的认为是一个无耗的传输媒介，在以上设计的圆波导内可以无耗地单模传输1.76GHz至2.42GHz频率的工作在TE11模式的电磁波。The circular waveguide of the present invention can be approximately considered as a lossless transmission medium when the length is relatively short, and the circular waveguide designed above can losslessly transmit the frequency of 1.76GHz to 2.42GHz in the TE11 mode electromagnetic waves.
TE11模式的电磁波在圆波导内传输并透射通过石墨烯片，由于法拉第旋转效应，每片石墨烯在磁场偏置的情况下会和TE11模式的电磁波相互作用，因此在完成透射时透射波会较入射波发生一定角度的偏转，该偏转角度的大小和外部的偏置磁场之间紧密相关，在经过9层石墨烯后可以达到设定所需的偏转角度。The electromagnetic wave of TE11 mode is transmitted in the circular waveguide and transmitted through the graphene sheet. Due to the Faraday rotation effect, each sheet of graphene will interact with the electromagnetic wave of TE11 mode under the condition of magnetic field bias, so when the transmission is completed, the transmitted wave It will be deflected at a certain angle compared with the incident wave, and the size of the deflection angle is closely related to the external bias magnetic field. After passing through 9 layers of graphene, the required deflection angle can be set.
外部的螺线管可以提供一个可调的偏置磁场，该偏置磁场方向和波的传播方向相平行，与石墨烯片相互垂直。通过调节外部螺线管线圈中电流的大小来控制产生的偏置磁场的强度，从而起到控制旋转角度的效果，还可以通过改变流入电流的方向来实现对旋转方向的控制。图2为磁场强度随电流大小变化的关系图，由图可知磁场强度和电流的大小成正比关系。An external solenoid can provide an adjustable bias magnetic field, which is parallel to the wave propagation direction and perpendicular to the graphene sheet. By adjusting the magnitude of the current in the external solenoid coil to control the strength of the generated bias magnetic field, so as to control the rotation angle, and to control the rotation direction by changing the direction of the inflow current. Figure 2 is a graph showing the relationship between the magnetic field strength and the magnitude of the current. It can be seen from the figure that the magnetic field strength is proportional to the magnitude of the current.
旋转器旋转角度随磁场强度变化的曲线如图3所示，旋转角度随着磁场强度的增强而变大，在达到一个最大值以后缓慢减小。旋转器的幅度特性随磁场强度变化的曲线如图4所示，幅度特性随着磁场强度的不断增强而增大。图5表示在磁场强度为0.18T时旋转角度随频率的变化曲线，由图可见，在该磁场强度下整个频段内的旋转角度都大于45度。结合图2和图3的结论可知，只要通过减小电流便可减弱磁场强度，其旋转角度便会随之减小，这样就可以达到设计目标，即旋转角度可以在0至50度之间调节。The curve of the rotation angle of the rotator changing with the magnetic field strength is shown in Figure 3. The rotation angle increases with the increase of the magnetic field strength, and decreases slowly after reaching a maximum value. The curve of the amplitude characteristic of the rotator changing with the magnetic field intensity is shown in Fig. 4, and the amplitude characteristic increases with the continuous enhancement of the magnetic field intensity. Figure 5 shows the variation curve of the rotation angle with frequency when the magnetic field strength is 0.18T. It can be seen from the figure that the rotation angle in the entire frequency band is greater than 45 degrees under this magnetic field strength. Combining the conclusions in Figure 2 and Figure 3, it can be seen that as long as the magnetic field strength can be weakened by reducing the current, its rotation angle will decrease accordingly, so that the design goal can be achieved, that is, the rotation angle can be adjusted between 0 and 50 degrees .
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| CN201310063099.5ACN103985938B (en) | 2013-02-07 | 2013-02-07 | Magnetic based on Graphene is adjustable Faraday rotator |
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| CN201310063099.5ACN103985938B (en) | 2013-02-07 | 2013-02-07 | Magnetic based on Graphene is adjustable Faraday rotator |
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