基于矩量法的微带天线优化设计

【作者】 刘钦凯；

【导师】 杨峰；

【作者基本信息】 电子科技大学 ， 电磁场与微波技术， 2008， 硕士

【摘要】 随着现代无线通信技术的迅速发展和应用,使得通信系统不断向集成化以及高性能化的方向发展。分析设计紧凑的、高性能的微带天线已成为当前国内外研究的前沿课题之一。本论文以矩量法(MOM)这一数值计算工具为基础,对增加微带天线的带宽、提高增益、以及减小微带天线之间的互耦进行研究。论文主要包括三个方面的内容:首先,利用互易定理,导出无限大地板模型下的积分方程,用脉冲基函数对电流展开进行矩量法求解;另外,把探针馈电方式简化为面结构的馈电模型,利用体面积分方程(VSIE)对有限大地板模型下的微带天线计算分析。通过与HFSS仿真软件的计算结果以及实验结果的对比,来判定矩量法计算的正确性。其次,结合遗传算法(GA),通过改变微带贴片形状,把微带贴片剖分为矩形的小贴片,对其编码和各种操作,使其满足一定的带宽要求。由于矩量法中阻抗矩阵与遗传算法中染色体的编码串都与微带贴片的分割单元相联系,而脉冲基函数对应的是矩形剖分单元,所以计算比较简单。本论文分别对不同介质厚度的微带天线优化,优化结果说明了算法的有效性。最后,用等效电路模型对电磁带隙结构(EBG)的单元间距、单元尺寸等参数做了分析。通过对不同形式电磁带隙结构微带天线的计算,考查了电磁带隙结构对微带天线增益、带宽的作用,计算结果说明参数合理的电磁带隙结构的应用对提高微带天线增益、增加微带天线的带宽有一定的作用;另外,把电磁带隙结构应用到微带天线阵列中,分别计算了不同间距的电磁带隙结构二元微带天线阵,计算结果说明其对减小微带天线之间的互耦具有明显的作用,降低了8.3dB。更多还原

【Abstract】 With the fast development and the wide application of the modern wireless communications technology, the communications systems are required to be compact and high-performance. The design of compact and heigh-performance microstrip antenna is becoming one of the most advanced subjects at home and in the world. In this dissertation, the problems that how to increase the band width, how to improve gain of the microstrip antenna, and how to reduce the mutual coupling between microstrip antennas are studied based on the method of moments(MOM).The dissertation is classified into three parts stated as follows.Firstly, the integral equation of the infinite floor model, which is solved by the method of moments, is derived based on the reciprocity theorem; otherwise, to simplify the probe feed model ,the finite floor model of the microstrip antenna is analyzed based on the volume and surface integral equation(VSIE).The algorithm are validated by contrasting the results with the results of the HFSS and the experiment.Secondly, the genetic algorithm(GA) is used for optimizing the bandwidth via changing the patch shap. The short rectangular patchs divided by the patch are coded and operated by genetic algorithm operation, and than the patch will besatisfy the certain request of the band width. Because the impedance matrix and the chromosome code string are all related with the element of the divgision, and the pulse base function is corresponding with the rectangular unit, it is easy to calculate. this dissertation discusses two microstrip antennae different thickness medium, and the optimization results show the effectiveness of the algorithm.At last, the unit spacing and cell size of the electromagnetics band-gap(EBG) are studied with the equivalent circuit model. this dissertation studied the gain and the bandwidth effected by EBG via calculating different forms EBG structure microstrip antennae. The results show that the EBG structure wit reasonable parameters is useful for improving the gain of the microstrip antenna and increasing the bandwidth. otherwise, the EBG structure is applied into the microstrip antenna array. this dissertation calculates two different distance microstrip antenna arrays. The results shows that mutual coupling is significantly reduced from -14.4dB to -23.7dB.更多还原