Study On Planar Feed In Multilayer Cavity Filter

With the development of commutation technology,especially the rapid rise of the mobile Internet,a large amount of information required for transmission by means of communications equipment.Microwave spectrum resources can no longer meet current social demands,then it is trend to develop high frequency spectrum resources.Filter acts as a selective role in the whole system,its performance directly affects the communication quality.Cavity filter at high frequency band still has high Q value in which has bigger advantage than graphic filters in insert loss.Therefore,the cavity filter occupies a leading position in high frequency.However,filter size and no easy connection with other devices restricts their development prospects.MEMS,LTCC technology is a good way to solve this problem,but the price and processing period may not be torrent.This article issues on the planarization interface and the miniaturization of the cavity.In design,using cross-coupling between resonators and new resonance structure,we can reduce the volume as far as possible.In the process,the external circuit is printed on the PCB substrate to implement the planarization of the interface,and the energy is coupling into the cavity through the back slot of the substrate.According to the basic principles and coupling theory,we design and test several filters.Main content can be summarized as follows.Firstly,we discuss metal resonators and coupling structures,then design a Ku-band cavity filter with simple structure.In order to realize the interface planarization,external coupling circuit is printed on the PCB substrate and then through the slot-coupled to the resonator.In order to achieve miniaturization,six cavity resonators has three layers vertically stacked,each layer has two resonator cavities.Secondly,we study in-depth the theory of half wavelength resonator and design three new Ka-band cavity filter with a litter more complicated.In order to realize the interface planarization,external coupling circuit is printed on the PCB substrate and hen through the slot-coupled to the resonator.It operates as a ?/ 2 TEM line resonator;this type filter has a smaller volume and wider stopband than waveguide.Thirdly,Using MEMS technology designs and produces two versions of W-band filters.The structure of the filter consists of four side-by-side horizontally oriented cavities.By comparing reflected better performance of generalized Chebyshev filter.