Study On Cascade Techniques For Substrate Integrated Waveguide Dual-mode Filters

The Substrate Integrated Waveguide (SIW) is a newly developed microwave transmission line, which is a kind of new waveguide that can be integrated in dielectric substrate with low insert-loss, high Q, high power capability, small size and easily integrated. Besides these advantages of both waveguide and microstrip, it can be fabricated by Printed Circuits Board (PCB) process. Filter produced with SIW technique not only has the advantages of microstrip filter in the respects of weight and size but also has a good performance as waveguide filter does. So, SIW filter design techniques have been one of the hotspots of the microwave filter design in recent years.This thesis studies on the design techniques of multi-resonator dual-mode filter which take the square SIW dual-mode resonator as a basic unit, and gives several kinds of coupling structures which are suitable for cascading dual-mode resonators, they separately are cascading on one board by making through-window with compensation or coupling from upper media layer and cascading from upper media layer to lower media layer by making through-window. Through these measures mentioned above, this thesis gives three SIW bandpass filters cascaded with two resonators and a three-resonator cascading filter that each resonator is on the different layer, besides, two kinds of cascading filters with four resonators on two layers are designed by using those measures given behind. The results of design simulation show that these filters all relatively have high attenuation in stop-band, low inter-loss in pass-band and good coefficient of rectangle. The FBW of three-resonator filter is 5.6%(f0=2.5GHz), the average attenuation in stop-band is lower than -50dB. The FBW of four-resonator filters are 6% and 5%(f0=2.5GHz), the average attenuation in stop-band is lower than -70dB.