Research And Design Of Miniaturized And High Performance Multi-band Filter

In recent years,with the development of the fifth generation(5G)mobile communication,the communication spectrum has been further improved,which solves the problem of limited available radio frequency(RF)spectrum resources.Similarly,in order to meet people's pursuit of high-speed communication,the quality threshold of microwave wireless system is also increasing day by day.As an indispensable part of the microwave wireless system,the performance of microwave passive devices is particularly important.However,the band-pass filter(BPF)has become the key role of passive devices in modern microwave wireless communication systems for keeping signal transmission in the passband and signal attenuation in the stopband.Its performance directly or indirectly affects the performance of the whole RF circuit.Therefore,the RF puts forward higher and higher requirements to miniaturization and high performance of the filter.In order to increase the utilization efficiency of the spectrum,the filter is gradually developed in the direction of multi-band.In this paper,a miniaturized,high-performance,multi-band bandpass filter is discussed in depth to meet the current needs.In this paper,the importance of designing miniaturized,high performance and multi-band filter is explained by introducing the research status of plane filter at home and abroad and some basic theories used in designing filter.Secondly,based on the step impedance resonator(SIR)theory,the step impedance resonator has better advantages of stopband suppression and compact structure.Based on the traditional analysis methods,a new filter coupling structure--hybrid microstrip/defect ground structure is proposed.Then,the filter model is simulated and optimized by using the traditional analysis method and the electromagnetic field simulation software,such as IE3D and ADS,which greatly improves the working efficiency.Meanwhile,the influence of key parameters on the filter's response and reasons are studied.Finally,a wide-stopband dual-band bandpass filter based on hybrid microstrip/defect ground structure is designed.The passband consists of stepped-impedance defect ground structures(DGS)at the bottom and a step impedance resonators at the top.At the same time,the harmonic positions of the stepped-impedance defect ground structure and the microstrip step-impedance resonator are separated from each other,which solves the attenuation of the stopband signal response.This is an important link in the filter design to realize the wide stopband response.In the design,the dual-band resonates at 2.39GHz and 5.30GHz,and the 3dB bandwidth is 16.1%and 8.8%,respectively.At the same time,the passband has a good degree of selection.The size is only 20mm·20.8mm(0.21?g·0.22?g,where?g is the full wavelength of the microstrip resonator working at 2.39GHz);The measurement results show that the stopband suppression range can reach 35 GHz,which is 14.6 times of the first resonant frequency f₁,and the suppression level can reach more than 20 dB.