Research And Design Of Miniaturized High Performance Filter

In recent years,the growing demand of mobile communication has accelerated the development of new broadband wireless systems.Due to the limited available radio frequency?RF?spectrum resources,it is necessary to develop various new technologies to increase the utilization of spectrum resources.In the fifth generation?5G?mobile communication,in addition to the existed UHF band,it is also assumed to use the new SHF band,whose goal is to enhance the operation of multi-band multiple access.With the rapid development of microwave wireless system,the performance of microwave passive devices is particularly important.Among them,bandpass filter?BPF?is an important part of signal selection and interference suppression in modern microwave system.Its performance directly or indirectly affects the performance of the whole microwave or RF circuit.Therefore,it is required that the filter not only have a good performance,but also it should be compact.In addition,RF interference is a serious problem in modern microwave channel systems.For example,in many wireless systems,bandpass filters made by plane material are usually used to suppress unwanted noise signals,mainly for RF and modern microwave applications,because they can effectively suppress spurious frequencies.Scholars have proposed a large number of filters with different performance and different structures in these years.In order to further improve the performance of multi-purpose RF front-end,people are more and more interested in miniaturized high performance filters.In this paper,according to the requirement of miniaturization and high performance broadband filter,the design of broadband filter based on the structure of plane is studied.Firstly,in this paper,by introducing the filter research status and some basic theories used in designing of filters,according to the continuous improvement of filter performance requirements in practical application,it expounds the importance of designing high performance filter.Then,using IE3D,HFSS,ADS and other electromagnetic simulation software,by using plane structure,two new high-performance broadband bandpass filters?BPF?are designed according to the theory,their equivalent circuit is deduced and the principle of these filters is analyzed.The first one is a compact wide stopband wideband bandpass filter,which is composed of two different layers of metal symmetrical resonators and a stopband filter.The typical insertion loss is 0.45 dB,the FBW of 1dB is 50%,the upper stopband is widened to 20GHz?the return loss is below-22 dB?,and the size is 7.75 mm×20.4 mm?0.09?_g×0.25?_g?;Another filter is composed of a three-layer metal third-order bandpass filter based on a novel packaged defective ground structure?PDGS?and two asymmetrical stepped-impedance lines,and it is a centered at 1.695 GHz and wide upper stopband bandpass filter.Meanwhile,the measured results are in a good agreement with the simulated results.The bandpass filter has the following advantages:low insertion loss?the typical insertion loss is 0.5 dB?and the broadband width?the FBW of 1 dB is67.8%?,under the compact size of 0.00612?_g²,the stopband is wide?the suppression level can reach below-17.8 dB up to 12.98 f₀,the suppression level can reach below-30 dB up to 5.37 f₀?.