The Study Of Microwave Cavity Bandpass Filter Based On 3D Printing Technology

Today,with the rapid development of communication technologies,filters are an important component of signal processing,and the demand is also increasing rapidly.However,the filter made by the traditional processing method has many limitations in the design and processing of the device,because it has heavy weight,processing cost is directly proportional to the complexity,and processing structure is related to precision.And the traditional tunable filter put most of the energy into the late debugging stage,which is acceptable when the number is small,but if the number is large or the structure is complicated,the amount of debugging tasks in the later period is too large.For this reason,we try to machine the device with 3D printing technology.The 3D printing technology is also called "additive manufacturing".According to the raw materials,it can be divided into a molten material system,a discrete particle system,a solid sheet system,and a liquid polymer system.The SLA printing method used in this article is a liquid polymer system.The specific processing method is as follows: the generated 3D model is layered and preprocessed in the system,a support frame is added in the protruding part,the accuracy of the layer thickness is being determined,and the liquid resin is coated by the method of adding layers,and the laser is used to cure the desired part,and the unwanted part is still liquid,the molded device is then removed and placed in an oven for reinforcement;finally,a fully printed device is obtained,after it has been cleaned and polished,it can be metallized.In this article,two cavity filters are designed using 3D printing technology and the whole process of the design is described in detail.After introducing the filter background,theory,traditional processing techniques and their limitations,some basic principles of the design filter are introduced in detail,including the design of the premise background(the premise of the equivalent of the two-port network),the definition of the two-port network-related parameter,low-pass filter prototype,the conversion of band-pass filter,coupling matrix theory.Explaining the basic principle of the filter in this paper designs in detail which provides a theoretical basis for the subsequent filter design.Subsequently,the article describes the design steps of the X-band ten-cavity filter and the Ku-band fourcavity eight-mode filter in detail.First,the structure and order are determined according to the indicators,and then the details are optimized through the two-dimensional circuit.Combining the group delay method and Y matrix method to calculate the external coupling and optimize the initial value of the model.Finally,the optimization algorithm of the simulation software is used to further optimize the cavity.After processing,check the physical test results to prove the feasibility of 3D printing in the microwave cavity band pass filter processing.