Design Of Microwave Device Based On Simplified CRLH TL

Characteristics and applications of Composite Right/Left Handed transmission line(CRLH TL) are presented in this dissertation. However, the hardness for achieving the balanced state sets obstacles for its implementation in practice. To this end, simplified CRLH TL(SCRLH TL) is further proposed, featuring intrinsic wide bandwidth and nonlinear dispersion characteristics as those of the balanced CRLH TL, which can be easily regulated through adjusting its circuit element values.Size reduction and bandwidth expansion can be achieved by applying SCRLH TL to design microwave devices. However, investigation on pertinent optimization methods for SCRLH TL based microwave components is still rare. The main contribution of the paper lies in putting forward a novel dual-band impedance transformer(DBIT) grounded on the SCRLH TL. A system of linear equations fully ruling the DBIT performance is built up from the design specifications, which is successfully solved with numerical method. Furthermore, a systematic three-step optimization technique is conceived, assuring optimal layout parameters can be stably acquired through circuit simulation, two-and-half-dimensional(2.5D) electromagnetic layout simulation and three-dimensional(3D) full-wave simulation, without the need of artificial tuning.Two WLAN dual-band miniaturized microstrip Wilkinson power divider and directional coupler have been designed using the new DBIT and the three-step optimization technique. Their compact size as well as good dual-band operation performance have been demonstrated by fabrication and experimental tests, confirming the proposed synthesis method.