人工磁导体材料在低剖面天线设计中的应用研究

发布时间：2018-03-12 22:55

本文选题：人工磁导体材料(AMC)　切入点：低剖面　出处：《西安电子科技大学》2014年硕士论文　论文类型：学位论文

【摘要】：伴随着超材料(Metamaterials)研究的快速发展,利用各种人工电磁结构的非常规电磁参数对传统电磁器件的进行改进设计得到了工业界和学术界的广泛关注。另一方面,无线终端设备的体积越来越小,这对终端设备中的天线的提出了更加苛刻的要求,天线的小型化设计越来越成为设计者关心的重点问题。本文针对传统天线剖面过高的问题,利用人工磁导体材料(AMC)在特定频率范围内所具有的零反射相位特性,提出了几种具有低剖面特性的的小型化宽频带天线设计方案。首先,针对平面准八木天线放置于金属表面时由于镜像原理导致的阻抗失配问题,利用AMC结构的零反射相位特性,设计了一种低剖面宽带平面准八木天线。通过在准八木天线的辐射体下方引入AMC结构,抵消了由于镜像原理导致的阻抗失配,通过选用合适的介质基板以及天线尺寸,在获取低剖面的同时,在较宽的频率范围内获得了较好的阻抗匹配特性。为了验证设计,对天线的实物进行了加工测试。测试结果表明,该天线能够工作在8.8 10.48 GHz,剖面低至0.14λg(λg为中心频率对应介质波长)。同时,在整个工作频带内,该天线具有37°到47°之间的波束上倾角。其次,针对传统双极化基站天线设计中天线单元剖面过高的问题,采用AMC结构作为双极化天线的地板,对天线的剖面进行了大幅度的降低,所设计的低剖面基站天线的剖面仅仅为传统的双极化基站天线剖面的一半。同时,方形AMC结构在几何外形上的对称性,保证了其在低剖面双极化天线中的优良性能。利用仿真软件对所设计的天线的结构尺寸的进行了优化,使得天线可以在较宽的频率范围内实现良好的阻抗匹配特性,最终对天线实物进行了加工测试。实验结果表明,本文所提出的双极化天线能够在实现宽带工作特性(2.12 2.77 GHz),天线的端口隔离度达到-35dB,天线的后向辐射得到一定的抑制,与普通双极化天线相比,波瓣前后比提高9dB。最后,针对传统的AMC结构的带宽和小型化之间的矛盾,在缺陷地AMC结构的基础上,提出了互补型AMC结构单元。与缺陷地AMC结构相比,互补型AMC结构更加简单,更加便于优化设计。通过电磁仿真软件对互补型AMC结构的电磁特性进行了分析,结果证明,该种结构能够在实现AMC结构单元小型化的同时实现较宽的工作带宽。最后,通过采用互补型AMC结构,结合弯折单极子天线,设计了一种低剖面宽频带弯折单极子天线。最终所设计的弯折单极子天线能够在较宽的频带内(4.5-5.67 GHz)实现良好的阻抗匹配,天线在整个工作频带内增益大于4dBi,效率大于85%。
[Abstract]:With the rapid development of metamaterials research, the improved design of traditional electromagnetic devices using various unconventional electromagnetic parameters of artificial electromagnetic structures has attracted extensive attention in industry and academia. The size of wireless terminal equipment is becoming smaller and smaller, which puts forward more stringent requirements for antenna in terminal equipment. The miniaturization of antenna design has become an important concern of designers. In this paper, the traditional antenna profile is too high. Based on the zero-reflection phase characteristics of artificial magnetic conductor material (AMC) in a specific frequency range, several design schemes for miniaturized broadband antennas with low profile characteristics are proposed. Aiming at the impedance mismatch problem caused by the mirror image principle when the planar quasi-octagonal antenna is placed on the metal surface, the zero-reflection phase characteristic of the AMC structure is used. A low profile wideband planar quasi-octagonal antenna is designed. By introducing AMC structure under the radiator of the quasi-octagonal antenna, the impedance mismatch caused by the mirror image principle is counteracted, and the appropriate dielectric substrate and antenna size are selected. At the same time, a better impedance matching characteristic is obtained in a wide frequency range. In order to verify the design, the processing test of the antenna is carried out. The test results show that, The antenna is capable of operating at 8.8 ~ 10.48 GHz with a profile as low as 0.14 位 g (位 g is the center frequency corresponding to the dielectric wavelength). Meanwhile, the antenna has a beam-on-beam inclination angle of 37 掳to 47 掳in the whole operating frequency band. Secondly, Aiming at the problem that the antenna cell profile is too high in the traditional dual-polarization base station antenna design, the AMC structure is used as the floor of the dual-polarization base station antenna, and the antenna profile is greatly reduced. The profile of the low profile base station antenna is only half of that of the traditional dual polarization base station antenna. At the same time, the symmetry of the square AMC structure in geometry is obtained. The excellent performance of the antenna in low profile dual polarization antenna is guaranteed. The structure size of the designed antenna is optimized by using the simulation software, so that the antenna can achieve good impedance matching characteristics in a wide frequency range. The experiment results show that the dual-polarization antenna proposed in this paper can achieve the wideband operating characteristics of 2.12 ~ 2.77 GHz, and the isolation degree of the antenna is -35 dB, and the backward radiation of the antenna can be restrained to a certain extent. Compared with the conventional dual-polarization antenna, the wavefront and back lobe ratio is increased by 9 dB. Finally, in view of the contradiction between the bandwidth and miniaturization of the traditional AMC structure, a complementary AMC structure unit is proposed on the basis of the defective AMC structure, which is compared with the defective AMC structure. The structure of complementary AMC is simpler and more convenient for optimization design. The electromagnetic characteristics of complementary AMC are analyzed by electromagnetic simulation software, and the results show that, This kind of structure can realize the miniaturization of AMC structure unit and realize wide working bandwidth at the same time. Finally, by adopting the complementary AMC structure and combining with the bending monopole antenna, A broadband bending monopole antenna with low profile is designed. The designed antenna can achieve good impedance matching in a wide frequency band (4.5-5.67 GHz). The gain of the antenna is greater than 4dBiand the efficiency is more than 85GHz in the whole operating band.
【学位授予单位】：西安电子科技大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TN823.27

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