一种基于分形结构的树生长微带天线设计

Design of a tree-growth microstrip antenna based on fractal structure

基于分形理论和自然树竞争(TGCA)思想,提出了采用树枝结构在不同生长因子下进行迭代生长的方法,对分形天线多谐振频率点进行优化控制,克服常见分形天线难于调整多个谐振频率点位置关系的缺点。树生长分形天线通过生长因子和天线尺寸的线性调整,可以方便地实现高低谐振频率的优化设计,方法简单易行。基于该方法,采用时域有限差分(FDTD)算法优化设计了一种具有GSM900/DCS1800双频谐振点的树生长微带分形天线。从实验和仿真结果可以看出,该微带分形天线在0.91 GHz,1.81 GHz谐振频率处带宽均大于100 MHz,水平方向为全向辐射,测量所得结果和仿真数据吻合较好,验证了采用生长因子调整分形天线谐振频率的方法。

Based on the fractal theory and the idea of the Tree Growth Competition Algorithm(TGCA), a method of optimizing the resonant frequencies by iterating the branch structure at different growth factors is proposed, which overcomes the inconvenience in adjusting the position relationships of multi-band frequencies for common fractal antennas. The lower and upper resonant frequencies of the tree-growth fractal antenna can be optimized conveniently by linearly changing its size and growth factors. Based on this method, a tree-growth fractal antenna is optimized in the GSM900/DCS1800 frequency band by using Finite-Difference Time-Domain(FDTD) algorithm. The measured and simulated results indicate that the bandwidths of microwave fractal antenna are both above 100 MHz at the resonant frequencies of 0.91 GHz and 1.81 GHz with good omni-directional radiation patterns in the horizontal direction. These good agreements of the measured and simulated results validate the feasibility of the proposed method.