Research And Application Of Planar Circuits Based On Coplanar Waveguide

As the microwave technology has undergone widespread increasing applications as well as continuously strict requirements, microwave decices tends to be more compact, more convenient to integrate and more broadband, which result in the following development in microwave filed. On the one hand, new type microwave transmission lines have been presented and applied. On the other hand, applications of new structure and new technology are emerging in microwave circu-its.Coplanar waveguide(CPW) has been proved to be a promising planar transmission line for its easy integration, small radiation loss and design flexibility. Two ultra-wideband filter based on CPW are proposed in this thesis, both of which are simple designed, and easy processing, and achieve the relative bandwidth of 150% and 112%.In addition, ultra-wideband filters proposed in this paper adopt the interdigital coupling structure, defected ground structure(DGS) and photonic band gap structure(PBG), and successfully integrate these structures with CPW. This type of integration uses the tight coupling of interdigital coupling structure to realize the wide passband of CPW filter, meanwhile utilizes the frequency selective DGS and PBG structure to improve CPW filter stopband. Furthermore it is a meaningful exploration of planar microwave circuits which combine CPW with the new structure.Two CPW UWB bandpass filters are simulated and analyzed: a CPW UWB bandpass filer based on interdigital coupling structure and a CPW UWB bandpass filer based on PBG. Both usefulness of the interdigital coupling structure integrated with DGS and PBG are well verificated. Furthermore, the important design parameters such as coupling depth, finger number, DGS’s location, PBG unit’s shape are analyzed and compared. Finaly, these two filters are manufactured and tested. Test data and simulation data has a good consistency, which validates the feasibility of the design based on CPW.