| Metamaterial which has some peculiar physical properties has aroused wideattention all over the world recently. In the THz spectrum, the THz function devices canbe realized by using the strong electromagnetic response between metamaterial andelectromagnetic wave. As one of the new research focus in THz electromagnetism field,graphene also has a broad application prospect. This article followed the currentresearch hotspot in the field of electromagnetic functional materials. The analysis anddesign of many THz electromagnetic functional materials, devices and antenna areproposed and some of these models are processed and tested. The special properties ofelectromagnetic functional materials can be applied to the base station antenna design toimprove the performance. The author’s main contribution can be summarized as:1. Analysis and research of the metamaterial in THz spectrum. The materialproperties and resonant principle of traditional Split Ring Resonator in THz spectrum isanalyzed. The R-L-C resonance square loop structure is designed to overcome thedifficulty in processing and polarization sensitivity. For the correlation with materialcharacteristics and structure, by adopting the nested square loops and cruciform andsquare loop combination form, a variety of THz metamaterials which is insensitive toincident wave polarization with dual-band and tri-band characteristics is implemented.The sample is fabricated by using GaAs processing line and tested by THz-TDS system.The results agree well with the simulation, which verified the design.2. Design and analysis of THz electromagnetic functional device. On the basis ofthe square metal loop and duality theory, a THz band filter composed of hollow squareloop is designed. By using the semiconductor properties of n-type GaAs substrate, aTHz active modulator based on the square loop structure is designed and analyzed. Thetransmissivity can be adjusted by varying the voltage between the metal electrodes. Adual-band THz absorber based on square loop structure is proposed and it can realizemore than90%absorption at the peak point. The characteristics of the absorber areanalyzed and demonstrated by the method of equivalent surface impedance theory anddecoupling Fabry-Perot cavity model.3. Application research of graphene in the field of electromagnetism. Based on theconductivity model of graphene surface, a THz dipole antenna is designed. Comparedwith the traditional metal materials, the surface plasma resonance properties of graphene make it has a slow wave effect. The resonance length can reach one tenth or twentieth ofthe wavelength in the air, which greatly reduced the size of the antenna. And theresonance frequency of graphene can be changed by adjusting the chemical potential. ATHz reflection array antenna is proposed based on the graphene. The element spacing issmaller than one sixth of the wavelength in the air and has great potential in electricallycontrolling application. Based on the metamaterial structure, a THz graphene absorberis designed, which is analyzed by equivalent circuit theory. By using lithographyprocess, the THz absorber based on graphene is fabricated. The precision and quality ofsample are good, which laid the foundation for the next work.4. Application research of EBG structure in antenna design. Firstly, focus on thewireless communication system, two models of double coaxial feed patch antenna withlow cross polarization and high port isolation is design. On this basis, by using the EBGstructure as a reflection plate, two low profile dual polarized antenna with low crosspolarization and high port isolation is proposed. Compared with the previous design, theheight is lowered about a half and the front-back ratio is improved. Then, a circularpolarized antenna with low profile characteristic is design by applying high impedancereflector. The proposed antennas are analysis in detail and fabricated to verify the design.The introduction of electromagnetic functional materials lead a new way for antennadesign. |
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