The Research Of Microwave Band Pass Filter Based On Composite Right/Left -Handed Transmission Line

Filter as an important component has been widely used in the communications field, its characteristic will directly affect the performance of the microwave system. With the shortage of microwave resources, in order to produce better performance of the filter, new materials and technologies should be studied.Left-handed materials is a new research focus in the electromagnetic field, its unique characteristics of the double negative can significantly improved the performance of microwave devices. But left-handed materials does not exist in nature, in fact, it is an artificial composite medium.There are usually two preparation methods:resonant units,constituted by Split Ring Resonators and fine copper wires and transmission line structure.This thesis use transmission line structure which has non-resonant units to prepare Left-handed materials, analyzed and summarized the new transmission line-the characteristics and the physical implementation of Composite Right/Left-Handed structure transmission line.Use the special nature of the new transmission line,were respectively designed two kinds of microwave BPF:the two-units cascaded structure and the four-units cascaded structure of microwave BPF. Though HFSS software simulation,two kinds of BPF are both in line with the requirements of design parameters,and the latter has better. pass-band characteristics and filtering performance than the former. Finally,the thesis gave a complete program of the four-units cascaded structure of microwave BPF,and designed the Printed Circuit Board.After experimental analysis, microwave BPF based on CRLH transmission line not only achieved a small size requirement,but also has a broadband,high performance,low-loss and other excellent features. The thesis use microstrip line design, printed circuit fabrication,easy and low cost processing.Therefore,it has broad application prospects.