基于CRLH传输线结构实现平面微波器件的小型化

Realization of Miniaturized Planar Microwave Components Based on CRLH Transmission Line Structure

提出了利用CRLH(composite right\left-handed)传输线结构来实现小型化平面微波器件的综合方法。实现器件小型化的关键是因为构成CRLH传输线的单位元胞在其左手通带内的特性阻抗和电长度可以在一个很宽的范围内任意调整,并且单位元胞的尺寸因媒质均匀理论的要求而远小于信号传播的波长。文中首先提出了利用CRLH传输线实现指定特性阻抗和相移的阻抗变换段综合过程,随后通过全波仿真软件AnsoftHFSS基于不同的小型化阻抗变换段结构设计加工了中心频率分别为1.92GHz和10GHz的定向耦合器和三端口功分器,依据所设计器件的仿真优化结果进行了实物加工和测量,并将仿真和测量结果进行了比较,结果表明,新型的定向耦合器和三端口功分器在保证良好传输特性的同时,缩减了器件的尺寸。

The synthesis method to realize miniaturized planar microwave components by utilizing CRLH transmission line structure is proposed in this paper. Key to the size reduction is the possibility to control the electrical characteristics of these lines （namely electric length and characteristic impedance） over wide margins by means of a single cell structure in its left - handed passband, and that the dimension of the constituent unit along the direction of the energy propagation must be much smaller than signal wavelength at the frequencies of interest according to the medium homogenization theory. First, the general synthesis procedure to realize miniaturized impedance transformer with specified characteristic impedance and phase shift is presented. Then novel directional coupler and three-port power divider working at 1.92GHz and 10GHz, respectively, are devised based on different miniaturized impedance transformer structures through the full wave simulation tool Ansoft HFSS. Subsequently each corresponding prototype component is fabricated and measured. The simulation results are in good agreement with the experimental ones, showing that the novel components not only have good transmission characteristics but can realize great size reduction also.