面电阻型宽频超材料吸波器的研究

发布时间：2019-05-18 22:27

【摘要】：左手超材料由于其具有奇异物理性质如负折射效应、反常多普勒效应、反常古斯-汉斯位移和反常切伦科夫辐射等引起了广泛的关注。近年来,左手超材料在吸收器领域的应用也成为研究的热点问题。本文基于超材料的设计思想,提出了一种基于电阻膜的超材料吸收器,探究了其吸波机理以及各参数对吸收性能的影响,设计了三种工作在不同波段的吸收器并制备了样品,在微波暗室分别测试了它们的吸收性能。最后探究了超材料吸收器的雷达散射截面缩减性能。论文主要涉及以下几个方面:1.设计了一种基于电阻膜的树枝状超材料宽带吸收器,它是由树枝状超材料结构的氧化铟锡(ITO)导电膜、泡沫介质层、金属薄板组合而成。基于等效电路模型分析了电磁波被吸收的机理,数值模拟发现该吸收器表面阻抗能在很宽的带宽内与空气阻抗近似相等,进而实现宽频吸收。2.探究了树枝大小、面电阻、介质介电常数、厚度对吸收器吸收性能的影响。通过数值模拟发现,大树枝对应低频吸收,小树枝对应高频吸收;面电阻在几十欧每方至几百欧每方才能与空气阻抗很好的匹配;基于电阻膜的吸收器中间介质基板介电常数越接近空气,其吸收性能越好,吸收带宽越宽,选用了PMI泡沫,其具有高力学性能,低介电常数,轻质等优点;随着厚度增加,吸收带宽逐渐转向低频窄带吸收。等效电路中等效电容C值影响着电路谐振,只有当电阻膜结构和金属背板之间形成的等效电容需要达到一个最佳值,电路谐振才能达到最强,吸收带宽最大。3.仿真得到工作在X和Ku波段吸收器吸收率超过80%的频率范围为8GHz—27.9GHz。实验测试其样品反射曲线与模拟吻合的非常好,在8-17GHz实现了80%吸收,相对带宽达到了72%。且对斜入射下60°内吸收性能几乎不变,通过实验测试对比了不同厚度下的吸收器性能。对大树枝厚的吸收器和小树枝薄的吸收器进行大量仿真对比发现,大树枝、厚的介质基板对应低频吸收;小树枝、薄的介质基板对应高频吸收。由此我们增加厚度的同时增大树枝单元尺寸设计出了C波段吸收器和S波段吸收器,其厚度都为10mm。仿真表明C波段吸收器高于90%的吸收带宽为2.8-8.5GHz覆盖了整个C波段,S波段吸收器高于80%的吸收带宽为2.0-6.0GHz,覆盖整个S波段。设计组合C波段和S波段吸收器厚度为10mm,模拟结果表明高于80%的吸收带宽为2.3GHz-8.7GHz近似覆盖了S波段和整个C波段,实验测试其高于80%的吸收带宽为4GHz-8GHz和12GHz-14GHz。同时设计了组合X和Ku波段吸收器、C波段吸收器和S波段吸收器,模拟该吸收器在5mm时的吸收结果大于80%的吸收带宽为6.2GHz-18GHz,实验测试结果高于80%的吸收带宽为4GHz-17GHz。4.模拟探究了超材料吸收器对目标雷达散射截面的缩减性能,仿真对比了超材料吸收器和相同大小的金属板发现无论是扫频雷达散射截面还是不同频点E面或H面雷达散射截面,三种超材料吸收器在对应的吸收频段内对目标雷达散射截面都有明显缩减。最后实验测试了X和Ku波段吸收器的相对雷达散射截面,实验证实了在30°以内吸收率反射都明显低于相同大小的铜板反射。从实验上表明我们所设计的吸收器不仅在垂直入射下具有很好的RCS缩减性能而且小角度斜入射下也同时具备这种性能。
[Abstract]:The left-hand metamaterial has attracted wide attention due to its singular physical properties such as negative refraction effect, abnormal Doppler effect, abnormal Gus-Hans displacement and abnormal Cerenkov radiation. In recent years, the application of the left-hand metamaterial in the absorber field has also become a hot issue in the research. Based on the design idea of the super-material, a kind of super-material absorber based on the resistance film is put forward, the wave-absorbing mechanism and the influence of each parameter on the absorption performance are studied, and the three kinds of absorber with different wave bands are designed and the samples are prepared. Their absorption properties were tested in the microwave anechoic chamber, respectively. Finally, the radar cross-section reduction performance of the super-material absorber is explored. The thesis mainly deals with the following aspects:1. The invention discloses a dendritic super-material broad-band absorber based on a resistance film, which is formed by combining an oxide-tin (ITO) conductive film, a foam medium layer and a metal thin plate with a dendritic super-material structure. The mechanism of the electromagnetic wave absorption is analyzed based on the equivalent circuit model. The numerical simulation shows that the surface impedance of the absorber can be approximately equal to the air impedance in a wide bandwidth, so as to realize the broadband absorption. The influence of the branch size, surface resistance, dielectric constant and thickness on the absorption performance of the absorber was investigated. According to the numerical simulation, the large branches correspond to low-frequency absorption, and the small branches correspond to high-frequency absorption; the surface resistance can be matched with the air impedance in a few tens of ohms per square to a few hundred ohms; the closer the dielectric constant of the middle dielectric substrate of the absorber based on the resistance film is closer to the air, the better the absorption performance, The wider the absorption band, the PMI foam is selected, which has the advantages of high mechanical property, low dielectric constant, light weight and the like; and as the thickness is increased, the absorption bandwidth gradually turns to the low-frequency narrow-band absorption. The equivalent capacitance C value in the equivalent circuit influences the circuit resonance, only when the equivalent capacitance formed between the resistance film structure and the metal back plate needs to reach an optimum value, the circuit resonance can reach the strongest, and the absorption bandwidth is the largest. The simulation results show that the absorption rate in the X-and Ku-band absorbers is over 80% in the range of 8 GHz to 27.9 GHz. The experimental results show that the reflection curve of the sample is very good at 8-17 GHz, and the relative bandwidth is up to 72%. And the performance of the absorber under different thicknesses is compared by the experiment test. A large number of simulations are carried out on the large-branch-thick absorber and the small-branch thin absorber, and the large branch and the thick medium substrate correspond to low-frequency absorption; and the small branch and the thin dielectric substrate correspond to high-frequency absorption. As a result, we designed the C-band absorber and the S-band absorber with a thickness of 10 mm while increasing the thickness. The simulation shows that the absorption bandwidth of the C-band absorber is higher than 90%, the absorption bandwidth is 2.8-8.5 GHz, the whole C-band is covered, the absorption bandwidth of the S-band absorber higher than 80% is 2.0-6.0 GHz, and the whole S-band is covered. The design combined C-band and S-band absorber have a thickness of 10 mm, and the simulation results show that the absorption bandwidth above 80% is about 2.3 GHz-8.7 GHz, which covers the S-band and the whole C-band, and the experimental results show that the absorption bandwidth above 80% is 4 GHz-8 GHz and 12-14 GHz. The combined X-and Ku-band absorbers, the C-band absorber and the S-band absorber are designed, and the absorption bandwidth of the absorber at 5 mm is more than 80%, the absorption bandwidth is 6.2 GHz to 18 GHz, and the absorption bandwidth of the experimental test results is higher than 80% is 4 GHz to 17 GHz. The reduction of the scattering cross section of the target radar by the super-material absorber is simulated. The simulation and comparison of the super-material absorber and the same-size metal plate show that both the frequency-swept radar cross section and the different frequency point E-plane or H-plane radar cross section, The three supermaterial absorbers have a significant reduction in the scattering cross-section of the target in the corresponding absorption band. The relative radar cross section of the X-and Ku-band absorbers is tested in the last experiment, and the reflection of the absorption rate within 30 掳 is obviously lower than that of the same-sized copper plate. The experimental results show that the absorber designed by us not only has good RCS reduction performance under vertical incidence, but also has the same performance at the same time.
【学位授予单位】：西北工业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TB34

【相似文献】