Stub To Load The Structure Of Planar Microwave Filters

It is a great trend that the modern radio frequency and microwave communication systems are developed to miniaturization and integration more and more, as one of the devices of communication system front position, the microwave filters play important roles, and the performance of the whole communication system are affected by the performance of the filters. With the rapid development of semiconductor technology, the integration of the active devices of the communication systems has a great improvement. But the miniaturization of passive devices, mainly in antennas and filters, has progressed slowly, the miniaturization of the whole communication systems are limited. So, it is one of the most deserved researches about planar filter for low cost, miniaturization and high performance. In this thesis, the researches on miniaturization of dual-mode and multi-mode are given, including the discussion of characteristics of filters with stub-loaded structure, the experimental examples of the dual-mode and multi-mode filters are given.In Chapter I, the research background, signification, recent developments about planar microwave filters and the main work are introduced.Chapter II introduces the basic theory about microwave filter design, including the two ports microwave network, reviewing the transfer function forms of traditional filters, frequency conversion, some parameters about the filter, microstrip circuit components, the realization of common filers and so on.Chapter III mainly discussed the some characteristics of stub-loaded dual-mode filter, and its unique characteristics are studied from the aspect of electric field and circuit respectively. And then, based on this structure, a novel dual-mode dual-passband filter is proposed.In chapter IV, through a further study about stub-loaded dual-mode resonator, several novel structural multi-mode resonators are proposed. The equivalent circuit models are proposed, and the modal characteristics of the multi-mode resonator are analyzed, at last, several experimental filters are implemented to verify the design.In chapter V, a brief summary of the contents and innovations are given, and future research topics are expected.