Research On Electromagnetic Bandgap Filter And Power Divider With High Noise Suppression

With the rapid development of modern communication technology in recent years,people have gradually entered the era of 5G communication.The improvement of the integration of communication systems has led to a trend of reducing the size of various communication devices.As the key components of the front-end radio frequency module of the communication system,the filter and power divider undertake the important functions of signal screening and power distribution,and their performance plays a vital role in the quality of the signal transmission of the communication system.Therefore,it is great of significance to study highperformance,small-size filters and filter power dividers for the sustainable development of 5G communication technology.Based on the demands of mobile communications in the new era,this paper has completed the design and development of a variety of multi-band,high out-ofband rejection,small-sized bandpass filter(BPF)and filter power divider(FPD)in combination with the electromagnetic bandgap(EBG)structure.The main content of this paper is as follows:1.Proposed and designed an EBG bandpass filter with small size,wide bandwidth and high passband selectivity composed of multilayer dielectric substrate and vertically interdigitated capacitors(VIC).The filter solved the problem of considerable size and high insertion loss(IL)of the current EBG structure.By introducing the VIC capacitor structure inside the EBG resonator,the size of the filter is reduced.At the same time,the quality factor(Q)of the VIC capacitor is higher and the IL is lower.In addition,the design adopted the coupling between the source and the load to introduce two transmission zeros outside the band,which improved the band selectivity of the filter.Finally,the design introduced the ring slotline on the top layer to realize the input of the signal.Based on the above analysis,a small-sized,broadband and high passband selectivity BPF with two transmission zeros outside the band is designed and optimized,which an operating frequency is around 17 GHz.2.A novel tunable multi-band balanced BPF based on EBG and microstrip structure is proposed,in which the resonant cavity is composed of EBG structure and external lumped capacitors.For the purpose of achieving the multi-band characteristics,multiple EBG resonant cavities are connected in parallel,and a BPF with quint-band filtering characteristics is realized by utilizing the natural isolation characteristics between EBG adjacent resonant cavities.Furthermore,the microstrip-slotline transition structure(MSTS)and the coplanar waveguidemicrostrip transition structures are introduced on the basis of the BPF to achieve high common mode(CM)suppression in the simulation and measurement frequency range.This design also innovatively introduced a multi-ring slotline structure inside the device,which solved the problem of high IL that is difficult to overcome in traditional multiband filters.In addition to the characteristics of more passbands,higher common mode(CM)suppression,and narrow band,the filter can also change the operating frequency range of the five bands by adjusting the value of the external lumped capacitor.3.A balanced quint-band dual-channel FPD composed of a double-layer dielectric substrate,optional external capacitors and resistors is proposed.The dielectric substrate part is processed and manufactured by printed circuit board(PCB)technology and the capacitor part adopts an external lumped capacitor with a high Q.By introducing a quarter-wavelength microstrip branch structure,the balanced-to-unbalanced conversion of the output port is realized.In addition,an optional external resistor is introduced inside the FPD to improve the isolation of the output port.Compared with the same type of FPD,the proposed structure has advantages in size,number of bands and output isolation due to the addition of the EBG structure.Finally,the proposed balanced quint-band dual channel FPD is processed and measured,and the experimental results are in agreement with the simulation,showing high consistency.