Studies On Compact Substrate Integrated Waveguide Filter

With the rapid development of modern communication technology, therequirements of microwave devices become more stricter. Complex-functionality andhigh-performance are required; on the other hand, small-size, portability and low-costare required, simultaneously. Low-cost, high-performance and high-yield microwavetechnologies are very important for developing economical and low-cost microwavebroadband systems. Hence, it is necessary to develop new microwave devicestechniques.Substrate Integrated Waveguide (short for SIW) is a new kind of microwavetransmission structure which can be widely used in microwave circuits. SIW has boththe advantage of rectangular waveguide which is a high Q-factor and low radiation loss,and microstrip which is small-size, light-weight, easy-machining and easy-integration.SIW is composed by two metal plates and two linear arrays of metalized vias whichhave the same center to center spacing. The center to center spacing of vias is so smallthat the radiation loss is reasonable to ignore. That is to say, the SIW structure is equalto dielectric-loaded rectangular waveguide and the microwave devices made by therectangular waveguide can be also realized by SIW structure, such as power dividers,filters, antennas, couplers, etc.Researches on the theory and technology of compact SIW filter have been done inthis dissertation．Firstly, some basic performance parameters of filters are introduced, the principleof metamaterial and a filter synthesis method by coupling matrix is discussed. Secondly,we introduce the field modes and propagation characters of rectangular waveguide, andmake a research on the condition of equivalent. Then, some important miniaturizationtechniques are introduced and discussed. Finally, based on the theories and methodsmentioned above, we designed two filters with HMSIW and QMSIW, respectively,combined with novel CSRR and coupling structure. The designed process is discussedin detailed in this paper. Compared with the recently reported BPFs, the proposed filtersnot only have the widest stopband bandwidth, but also have the most compact size andbetter selectivity.