The Research And Design Of Interdigital Bandpss Filter

With the rapid development of the mobile communication industry, the electron counterdevices and the technologies of navigation in recent years, the demand of new microwave circuits and components and the require of improving the existing microwave circuits and components is very high . As one of the important microwave components, the microwave filters also developed rapidly in recent years. Especially, the microwave bandpass filters directly influence the performances of the receivers. Therefor, the home and foreign engineers of microwave components are very interested in the research of theoretical analysis and practical design for the microwave filters.This paper gives the particular description of theoretical analysis and practical design for a suspended interdigital bandpass filter which used for rejection the mirror image frequence of a superheterodyne receiver . Based on computer aided design, the parameters of the filter are given and simulated. A filter with a passband of 4.8GHz to 5.2GHz has been designed, built, and tested.At first, this paper introduces the classes of microwave filters, the current of development, the main problems and the main interferences of the receiver; in this part it also discusses the method of design the microwave bandpass filter, and especially introduces the theory of design the suspended interdigital bandpass filter in particular. Secondly, based on the method which introduced in the first part, using the advanced mathematical.tool - Matlab, it can work out the initial dimension values of the microwave bandpass filter; Thirdly, using the advanced microwave circuit simulation software (HP-ADS), it can model the suspended interdigital bandpass filter, and simulate, optimize the initial dimension values, so as to gain the final dimension values and the simulated graphs of the suspended interdigital bandpass filter. Finally, based the final values, using the software (Auto CAD), it can draw the mechanical manuscripts, and gain the microwave bandpass filter. We using the sealer network analyzer to test the performance of the filter, and gain the experimental graphs. From comparing the simulated graphs with the experimental ones, we can easily find the experimental results agree well with the simulated ones, and the way of combining the traditional theory with the advanced computer technology is very effective. The microwave bandpass filter can bascially achieve the initial demand of the product.