| In recent years, with the rapid development of radio communication technology, designof high performance filter has very important significance for the whole communicationsystem. Microwave filter can selective frequency and eliminate the noise. However, usingmicrowave filter synthesis theory to design traditional filter is generally difficult to meet therequirements of the system. A method to solve the complex problems is the introduction ofoptimization algorithm. As a new bionic optimization algorithm, Invasive WeedOptimization (IWO) algorithm has been widely used. In this thesis, IWO algorithm isstudied, and then it is used to design microwave filters. The main concepts are as followed.1. Study of the IWO algorithm. The thesis introduces the basic principles of IWOalgorithm, and the algorithm convergence is introduced. Then, an improved IWO algorithmis proposed and programmed in Matlab. Some typical test functions are used to verify by theperformance of the algorithm.2. Optimization design of microwave filter. This thesis introduces the design theory ofmicrowave filter, and gives design method based on the IWO algorithm and HFSS3Delectromagnetic simulation software program. Parallel coupled line filter is design using themethod.3. Optimization design of narrowband microwave filter. The thesis introduces thecomprehensive theory of Generalized Chebyshev filter. The coupling matrix is eliminatedby IWO algorithm, designing the cross coupling filter using microstrip line and coaxialcavity. The test results are given.4. Optimization design of broadband microwave filter. Two design schemes of ultrawideband filter are presented. One is to cascade a low pass filter and a high pass filter. Thehigh pass filter is design by novel substrate integrated waveguide (SIW) devices, and thelow-pass filter is design by stepped impedance line. The other is to optimize the structure ofthe stub filter through the IWO algorithm, so as to realize the ultra wide bandcharacteristics. |
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