Simulstion And Design Of Broadband RF Filters

The frequency range of modern electronic communication equipment continues to expand, radio frequency and free space more crowded, interference and signal between the more obvious, to filter the requirements of communication system is also more and more high. The modern electronic products miniaturization, integration, which requires the filter to a size as small as possible, so the design of communication system for filter type should have an appropriate choice.Microwave filter is an important component of the microwave communication system, the microstrip filter is used as a microwave filter, and has the advantages of small volume, light weight, easy integration, strong anti-jamming ability and is widely used in microwave system.In this thesis, a microstrip bandpass filter design as the main line, introduced the research history and research status of the microstrip filter; discusses the basic principle of microstrip radio frequency filter. Low pass filter is the basis for all other types of filters, other types of filters can be determined by the low-pass prototype filter transformation, we first discuss the comprehensive method of the low-pass prototype filter, which are converted from low to high pass, band pass. Maximum flat approximation and Chebyshev approximation are two traditional synthesis method of low-pass filter, maximum flat filter approximation is theoretical foundation of comprehensive, integrated Chebyshev is a comprehensive method is used widely, this paper also gives in detail. Coupled with the resonance is the physical mechanism of filter microstrip filter, this paper discusses in detail the coupling matrix element and synchronously tuned resonant coupling resonance, the loop equation, nodal equations are analyzed in detail, the synchronous tuning coupling resonance electric coupling, magnetic coupling and electromagnetic mixed coupling analysis, were analyzed on the coupling coefficient and quality factor.The traditional synthesis method of calculation is complex, time-consuming and laborious, using software simulation is an effective shortcut, time-saving, this paper introduces the characteristics and functions of modern simulation software, including ADS, HFSS, Designer, CST, the application of the simulation software and their advantages and disadvantages are compared; the theory and modern simulation software combined, using ADS and Designer software design two cross coupled microstrip bandpass filter, and the even mode impedance characteristic impedance of odd mode characteristics first calculate the filter using equivalent principle, the characteristic impedance calculation software tool calculates microstrip line size parameters, optimization of these parameters, modeling and simulation, simulation of the coupling interval, tapped line position, resonator length factors such as the performance of the filter, the simulation results are analyzed and discussed.Make a sample of filter processing design, test the real filter, test results and theory results are compared, discussed the possible causes of test results and theoretical calculation results error and improvement measures.