【作者】 刘海燕；

【导师】 廖斌；

【作者基本信息】 华东师范大学 ， 电磁场与微波技术， 2010， 硕士

【摘要】 现代无线通信对器件小型化的要求越来越高,天线是通信系统的重要组成部分,所以天线的小型化设计也变得非常重要。如何使用更小的面积实现更低频率更好性能的微带天线已逐渐成为科研工作者与工程师们研究的重点和焦点。超材料(Metamaterials)作为一类新型的人工电磁材料,目前已经成为实现微带天线小型化的重要技术与手段。通过在传统的媒质材料(ε>0,μ>0)中水平或者垂直嵌入某种几何结构的单元,便可以获得ε<0或者μ<0的超常材料,它具有天然媒质所不具备的奇特物理性质。本文主要采用两种方法实现微带天线的小型化。一种是运用等效Smith结构,通过在传统微带半波贴片天线的地面水平加载各种不同形式的结构单元来实现微带天线的小型化。另一种是通过在介质基板中垂直填充某种结构单元构成复合材料,从而使得微带贴片天线的物理尺寸不主要取决于构成材料的本征性质,而取决于其中填充的人工结构,避免了微带天线物理尺寸与谐振频率的相互制约,实现了微带天线的小型化。通过软件仿真可以知道,使用传统的半波贴片,在10GHz频率辐射,需要尺寸14.98mm×9.29mm。若采用第一种方法,在介质基板下水平加载四个SRR(开口谐振环)结构,使用同样的贴片,可使谐振频率降至8.9GHz；若加载六个SRR结构,可使频率降至8.5GHz。在同样尺寸下,谐振频率分别下降了11%与15%,从而实现了天线的小型化。通过进一步的研究,发现若水平加载四个SR(螺旋谐振环)结构,可使频率降至5.9GHz；若加载六个SR结构,则可降至5.8GHz。在同样的贴片下,谐振频率下降了约42%,小型化的效果更加良好。若采用第二种方法,通过在传统介质中嵌入八个SR结构来实现负磁导率(u-negative)的超材料,可使谐振频率从2.45GHz降至434MHz,在低频段天线尺寸大幅减小,不仅实现了天线的小型化,还可以实现双频工作。更多还原

【Abstract】 Modern wireless communication devices are required to be miniaturized, while antenna is an important part of communication system. Many scientists and engineers focus on how to achieve better performance at lower frequency on microstrip antennas in a small area.As a composite or structured material that exhibits properties not found in naturally occurring materials or compounds, Metamaterial is an important approach to implement miniaturization of microstrip antenna.In this thesis, two methods are used to implement miniaturization of microstrip antenna. Load different types of structural elements on traditional media substrate to achieve the miniaturization. After the traditional media substrate is filled with the Metamaterial, microstrip antenna’s physical size primarily depends on constitutive parameters of Metamaterial. Therefore, the mutual constraints between the microstrip antenna’s physical size and resonant frequency are avoided.Numerical simulation shows that traditional microstrip antenna’s physical size is 14.98mm by 9.29mm at lOGHz. While using the first method, if 4 SRR (Split-Ring Resonator) structure under patch is loaded, the resonant frequency is down to 8.9GHz; if 6 SRR structure is loaded, the resonant frequency is down to 8.5GHz. Compare to the same patch size, the resonant frequency decreases by 11% and 15%, so miniaturization of the microstrip antenna is achieved. Further studies have shown that if 4 SR (spiral resonator) structure in the same place is loaded, which allows the resonant frequency down to 5.9GHz; if 6 SR structure is loaded, the resonant frequency can be reduced to 5.8GHz. In the same patch, the resonant frequency decreases by about 42%. Effects on miniaturization become pronounced.While using the second method, theμ-negative meta-materials is realized by filling substrate with 8 spiral resonators (SR), which can miniaturize the low frequency antenna, and the resonant frequency is from 2.45GHz down to 434MHz. Not only miniaturization of the microstrip antenna is achieved, but also dual-band work can be obtained.更多还原