Design And Research Of The New Band-stop Filter

In many microwave systems, the delivering of signal in the process must be weekpossibly, and the delivering of the interference signal which we don’t need must bestrong possibly. We can use a general microwave band-pass filter to carry out. But if theinterference signal is too strong, a general band-pass filter cannot have enoughattenuation to the interference’s signal. The filter which is designed for suppressing theinterfering signal must be used at this time, i. e. the band-stop filter. In addition, if at afrequency point we require a sufficiently high attenuation, a band-stop filter is muchbetter than a band-pass filter. The microwave band-stop filter has been widely applied inthe wireless communication system, the radar system, the field of measure currently.The conventional band-stop filter don’t have ideal rectangular coefficient whetherthe micro-strip structure or the waveguide structure is used to achieve a filter, and thereis the disadvantage of oversize. It is difficult to meet the requirement of miniaturizationof the modern filter.In this thesis, the basic principle of the microwave band-stop filter, the Basicstructure, the design method and its forms is discussed. We put a new band stop filter asthe main research object, for getting ultra-far spurious stop-band we dredged trench inthe capacitive loading of the band-stop filter’s resonators. The band-stop filter has theadvantages of ultra-far spurious stop-band, easy to adjust, and small size and so on. Thepaper will be given as follows:1. Introduce the design principle, the basic structure of the microwave band-stopfilter and then present two design methods of the band-stop filter, the design method ofthe narrow band band-stop filter and the exact design method of the band-stop filter.2. Introduce the capacitive loading of the band-stop filters design method. On thisbasis, present the measures to achieve farther spurious stop-band and miniaturization.3. In this thesis, we design a capacitive loading of the band-stop filter, and forgetting farther spurious stop-band, we dredge trench in the capacitive loading of theband-stop filter’s resonators; for achieving miniaturization, the main transmission line traces by S-type. This band-stop filter has advantages of the farther spurious stop-band,the deeper stop-band rejection, miniaturization and easy to adjust.