Research On Multiband Electromagnetic Bandgap Filter And Power Divider

With the advent of the era of 5G and interconnected,the communication system is developing towards the trend of integration,miniaturization,low cost,and multi-function,so the emergence of a new generation of high-performance communication equipment is urgently needed.In addition,various communication standards make spectrum resources increasingly scarce.Modern communication systems need to support several different working bands while satisfying miniaturization.As two core components in microwave passive networks,the filter and power divider usually appear in the system in a cascaded way,which undoubtedly increases the loss and size of the circuit.The filtering power divider integrates the filter and power divider to realize the function of frequency selection and power distribution.Consequently,based on the electromagnetic bandgap(EBG)structure,combined with the design theory of filter and power divider,a variety of high-performance multiband filters and power dividers are studied.The main research work of this paper is as follows :1.A novel quad-band filtering power divider based on the EBG structure is proposed.To reduce the size of the filtering power divider,eight pairs of resonators are integrated with the same EBG substrate to achieve a quad-band filtering response with good performance.At the same time,the high isolation between the output ports is achieved by adjusting the value of the resistance R.Secondly,the magnetic field of the EBG resonator mainly surrounds the resonate post,which reduces the signal interference between passbands and achieves better band-to-band isolation.In addition,the working frequency of each passband of the filtering power divider can be independently controlled by changing the capacitance value.Finally,a quad-band filtering power divider based on the printed circuit board(PCB)technology is fabricated.The center frequencies of the fabricated quad-band filtering power divider are 1.96,2.34,2.9,and 4 GHz,respectively,and the band-to-band isolation is better than 32.1 d B.In the frequency range of 4.21 to 8.0 GHz,upper stopband suppression is better than 22.7 d B.2.A four-way power divider with a dual-band filtering response is proposed.The dual-band filtering response is realized by integrating two sets of EBG resonators in each of the four signal transmission paths of the power distribution structure.The parallel RC isolation network is applied in the power distribution structure so that all output ports can realize perfect impedance matching.Compared with the traditional isolation resistance,the isolation network effectively enhances the output isolation of the filtering power divider.In addition,the filtering response and isolation characteristic of the four-way filtering power divider is designed by using coupling matrix synthesis and the odd-even mode analysis method,respectively.Finally,to verify the advantages of designing a high-performance four-way filtering power divider based on the EBG structure,a four-way dual-band filtering power divider with working frequencies of 2.18 GHz and 3.23 GHz is fabricated.The measured results show that the out-of-band rejection is better than 31.4 d B in the frequency range of 3.57 to 10.0 GHz.3.A novel eight-band filter based on EBG technology and coupling matrix synthesis method is proposed.The eight-band filter consists of eight sets of EBG resonators.The working frequency of each passband can be controlled flexibly by changing the capacitance value.To couple the energy to all resonators,a power divider is applied to the energy transmission circuit to improve the performance of the filter.To meet the needs of multi-band development of microwave devices in communication systems,an eight-band filter with center frequencies of 1.53,1.76,1.98,2.22,2.8,3.06,3.34,and 3.63 GHz is implemented,and the band-to-band isolation is better than 22 d B.