The Miniaturization Research And Design Of Cavity Filters

As a key component of wireless communication system,which is in a rapid development,the performance of the microwave filters has a very important impact on communication system.The research and development of the high-performance,low-cost,small-size microwave filters have a significant practical meaning for the future development of wireless communication system.In this paper,in view of the above objectives,we have a further research on dielectric filter and interdigital cavity filter,in which the dielectric material and load-capacity technique were used to decrease the size of filter efficiently.We will have a brief introduction of the history,study background,meanings and future trend of dielectric filters first in this paper.Then,some basic theories of microwave filer will be discussed.Then,we'll propose a dielectric dual-band pass filter according to the basic theories related to dielectric resonator.This filer consist of dielectric cavity and rectangular dielectric resonators,which are made by same material and connected as a whole.There is no need for any resonator supporting structure inside the cavity which is a necessity for conventional metal cavity filters and all the surface of dielectric cavity are silver-plated.With the help of EM simulation software,we can simulate and optimize the filter structure we proposed,then we'll get the 3-D model which meets all the design command.Next,we put forward another two designs of monoblock dielectric waveguide filter,which are made from a single piece of ceramic with dielectric constant?r?20.5 and we can reduce the size of filter by using dielectric material.All the surface of ceramic is plated with silver or metal compounds.By introducing the tuning and coupling blind holes we can fine tuning the processed filter,which is a guarantee of the yield rate.Besides,by introducing cross-coupling structure the performance of out-band suppression can be improved,and with the help of EM simulation software to build and optimize,we can get a 3-D model who's center frequency is f0=2.6GHz and bandwidth is BW=100MHz.At last,we'll present a interdigital filer applying for Vector network analyzer which designed by EM simulation software.This filter is made up of intertwined metal resonator with the length of ?/4,and we can efficiently reduce the size of this filter by load-capacity technique.Then,we can get this filter's 3-D model with center frequency f0=6.9GHz and bandwidth BW=1.3GHz.