新型电磁功能材料及其在天线设计中的应用

发布时间：2018-10-07 20:23

【摘要】：由于超材料具有一些天然材料所不具备的超常物理特性，，近年来引起了国内外学者的广泛关注。在THz频段，利用超材料与电磁波的强烈电磁响应，可以实现THz频段的功能器件。石墨烯作为近年来新材料研究中另一个备受关注的热点，在THz频段的电磁学领域同样具有广阔的应用前景。本文中紧随当今电磁功能材料领域的研究热点，分析并设计了多款THz频段的电磁功能材料、器件及天线，并对部分模型进行加工和测试；利用电磁功能材料的特殊性质，将其应用于基站天线的设计之中，提高性能并减小天线的尺寸。作者的主要工作及创造性成果可概括为： 1. THz频段超材料特性的分析和研究。分析传统开口谐振环在THz频段的材料特性及谐振原理，针对开口谐振环加工难度大和极化敏感的问题，提出同样基于R-L-C谐振的方形闭合环结构并详细分析其特性。利用材料特征的结构相关性，通过采用嵌套的方形环及方形环与十字形环组合的形式，设计多种在THz频段具有双频、三频特性且对入射波极化不敏感的超材料。使用砷化镓工艺线对样品进行加工并利用THz-TDS系统对材料的透射参数进行测试，测试结果与仿真结果吻合良好，验证了超材料设计的正确性。 2. THz频段电磁功能器件的设计与分析。在方形金属环的基础上，利用对偶原理，采用镂空方形环结构设计一款THz频段的滤波器并分析了其特性。利用n型砷化镓衬底的半导体特性，设计一款基于方环结构的THz频段的有源调制器并分析其工作原理，通过调节金属电极两端的加载电压改变其透射率实现幅度调制。设计一款基于方环结构的双频THz吸波材料，实现在峰值处超过90%吸收率的吸收特性，并通过等效表面阻抗理论及去耦的Fabry-Perot谐振腔理论分析吸波材料的工作原理，验证设计结果。 3.石墨烯材料在电磁学领域中的应用研究。在研究石墨烯表面电导率模型的基础上，对采用石墨烯材料的THz偶极子天线的特性进行了研究。与传统金属材料相比，石墨烯的表面等离子体特性使其产生慢波效应，天线的谐振尺寸可以达到十分之一甚至二十分之一空气中波长，大大减小天线的尺寸，并可以通过调节石墨烯的化学势来改变谐振频率。采用石墨烯材料作为贴片单元设计一款THz频段的平面反射阵天线，其单元间距小于空间波长的六分之一，并且单元的反射相位可以通过化学势来调节，使其具有电调的应用潜力。基于超材料结构设计一款THz石墨烯吸波材料，采用等效电路理论对其工作原理进行分析和验证，并利用光刻工艺对样品进行制作，样品的精度和质量都很好，为接下来的工作奠定了基础。 4.电磁带隙结构在天线设计中的应用。针对无线通讯系统的极化分集技术设计两款基于折合振子的双同轴馈电贴片天线，具有低交叉极化与高端口隔离度的特性。在此基础上，将电磁带隙结构作为反射板应用于基站天线单元设计，提出两款低剖面、低交叉极化、高端口隔离度的双极化天线单元。与之前的设计相比，其高度降低了一半且方向图的前后比得到提高。另外，采用高阻抗反射板设计了一款具有低剖面特性的圆极化天线。文中对所设计的天线进行详细的分析，并通过加工测试验证设计的正确性，天线的性能优越，可用于基站及无线热点等通信系统中。电磁功能材料的引入为天线设计开启了一扇新的大门。
[Abstract]:Due to the extraordinary physical characteristics of super-materials which are not possessed by some kinds of materials, it has attracted wide attention from domestic and foreign scholars in recent years. In the frequency band, using the strong electromagnetic response of the metamaterial and the electromagnetic wave, the functional device of the frequency band can be realized. As another hotspot in the research of new materials in recent years, graphene has a wide application prospect in the field of new material research. In this paper, the electromagnetic functional materials, devices and antennas are analyzed and designed in the field of electromagnetic functional materials, and some models are processed and tested. The special properties of electromagnetic functional materials are used in the design of base station antennas. improve performance and reduce the size of the antenna. The author's main work and creative achievements can be summarized as follows: 1. Analysis of the characteristics of ultra-high frequency band materials In this paper, the material characteristics and the resonance principle of the traditional open resonant ring are analyzed, and the square closed loop structure based on R-L-C resonance is put forward and analyzed in detail aiming at the problems of difficult machining difficulty and polarization sensitivity of the open resonant ring. By using nested square ring and square ring and cross-ring combination, a variety of ultra-high frequency bands with dual-frequency and three-frequency characteristics and insensitive to incident polarization are designed. Materials. The sample is processed by using the Bayer process line and the transmission parameters of the material are tested by using the Bayer-TDS system. The test results are well matched with the simulation results, and the design of the metamaterial is verified. true.................................................... Design and analysis. On the basis of square metal ring, by using the principle of duality, the square ring is used to design an octave band filter. In this paper, an active modulator based on square-loop structure is designed and its working principle is analyzed by using the semiconductor characteristics of n-type silicon carbide substrate. The transmissivity of the active modulator is changed by adjusting the loading voltage across the metal electrode. The amplitude modulation is designed. A double-frequency wave absorbing material based on square ring structure is designed to achieve the absorption characteristics of over 90% absorption at the peak, and the working principle and inspection of the wave absorbing material are analyzed by equivalent surface impedance theory and decoupled Fabry-Perot resonator theory. Certificate Design Results. 3. Graphene Materials Used in Chemical Engineering The application of graphene on the basis of studying the surface conductivity model of graphene is studied. Compared with the traditional metal materials, the surface plasma characteristics of the graphene make it slow wave effect, the resonance size of the antenna can reach one-tenth or even one-tenth of the wavelength in the air, the size of the antenna is reduced and the chemistry of the graphene can be adjusted by adjusting the chemistry of the graphene, The graphene material is used as a patch unit to design a planar reflective array antenna with a cell spacing less than one sixth of the space wavelength, Based on the metamaterial structure design, a novel graphene-absorbing material is designed, the working principle is analyzed and verified by equivalent circuit theory, and the sample is manufactured by a photoetching process, and the precision and the quality of the sample are good, and the method comprises the following steps: The work laid the foundation. The electromagnetic band gap The invention relates to an application of a structure in an antenna design, On this basis, the electromagnetic band gap structure is applied to the base station antenna unit design as the reflection plate, and two low profile, low cross polarization and high end ports are proposed. the height of the dual-polarized antenna unit of the isolation degree is reduced by half compared with the previous design, The front-to-back ratio of the direction chart is improved. In addition, a high-impedance reflecting plate is adopted to design a high-impedance reflecting plate. A circularly polarized antenna with low profile characteristics is described in detail in this paper, and the correctness of the design is verified by processing test. The performance of the antenna is superior to that of the base station. and wireless hot spots and the like, wherein the electromagnetic functional material is introduced into an antenna
【学位授予单位】：西安电子科技大学
【学位级别】：博士
【学位授予年份】：2014
【分类号】：TN820

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