The Research Of Microstrip Filter Based On The Composite Right/Left Handed Transmission Line

As a new type of metamaterial,the composite right/left handed(CRLH)material can present specific electromagnetic characteristics,thus CRLH material has been a hot research topic for decades.Due to the zero order resonance mode and negative order resonance mode of the CRLH transmission line(TL)structure,the material of CRLH TL has important utilization in microstrip filter component miniaturization.In this dissertation,we mainly use CRLH TL as a basic resonance unit cell to present filters.The basic unit cell includes interdigital capacitors in series and shorted stub inductors in parallel.We analysis dispersion curve and resonant mode of the CRLH TL,and present four different kind of miniaturized microstrip filters.The main contents of this dissertation are summarized as follows,We analysis the dispersion of the CRLH TL resonance,present equivalent circuit of it.Besides,we analysis the zero order resonance mode and negative order resonance mode of the ?/4 CRLH TL.We show the way to extract dimension parameters of the unit cell,thus to create filters theoretically.Use ?/4 CRLH TL structure as a basic unit cell,we propose DGS loaded broad-bandstop filter to restrain higher-order modes which can provide broader stopband for filters.Besides,we propose mixed coupling and cross coupling bandpass filters,by increasing transmission zero,we are aiming at improving frequency selective characteristic.We propose a ? UWB bandpass filter.Compared with LC filters,? UWB bandpass filter has lower insertion loss.In addition,it has more ripples in the passband to create broader passband.