The Investigation Of Dual-mode Bandpass Filter Based On Triangle SIW Cavity

Recently,due to the merits of high Q-factor,low-loss,low-cost,easily produced with PCB,LTCC technique and so on,substrate integrated waveguide(SIW)has attracted more attention.Additionally,SIW is becoming more and more popular in the microwave and millimeter wave circuits,especially,it is very useful in the field of SIW resonators to design a large number of high-performance filters.As is known to all,dual-mode technology can reduce one half of the original size,because two resonant modes can work in one resonator.In this case,dual-mode technology is attracting wide attention recently.In this investigation,owing to large quantities of papers have investigated circular and square dual-mode SIW cavities to achieve a great deal of bandpass filters,but isosceles triangle SIW cavities with the apex angle of 120 degrees are seldom studied.So the isosceles triangle SIW cavity with the apex angle of 120 degrees is used as the basic structure in this investigation.First of all,by analyzing the eigenmodes and incentives in the resonator,we investigate several dual-mode SIW resonator bandpass filters with different port positions to make benefits for the following study.Secondly,a wider bandpass and campact size filter is essential to meet the needs of more application design,thus we choose the cascading technology to design a two-cavity dual-mode bandpass SIW filter.By comparing usual coupling ways,we decide to choose simple magnetic coupling to cascade two basic resonators.Then to make the distribution of the electric field vectors in two cavities keeps consistent at any passband frequency,we can find it is very important to add metallic via-holes between the coupling windows.So that the metallic via-holes between coupling windows are indispensably used to optimize the performance of the filter.Finally,we talk about the relationship of Z,S parameters and so on.In the same way,we also use simple magnetic coupling to cascade three resonators.Afterwards,the advantages of the isosceles triangle SIW cavities with the apex angle of 120 degree are fully realized.