| In the information age,communication technology is developing rapidly.Compared with with previous mobile communication systems,the fifth generation mobile communication system(5G)has wider signal coverage,faster information transmission rate,and more stable communication.This series of changes promote the development of radio frequency(RF)passive devices.In order to adapt to the new development and changes of communication systems,broadband,multi-band,and multifunctional RF passive components are urgently required,which have low loss,low power consumption,high linearity,and compact size.Therefore,such passive differential phase shifters become a research hotspot.In this context,research on broadband,dual-band,and filtering passive differential phase shifters is carried out in this article.The main research contents are as follows:(1)Based on microstrip line,a novel compact single-layer wideband phase shifter using weakly coupled lines is proposed,which contains a main line and a reference line.The basic equations of this phase shifter are calculated based on the even-odd mode theory.Then,the parameters are determined in the design procedure.A compact wideband 90° phase shifter is designed,fabricated,and measured for demonstration.The measured results,in good agreement with the EM simulation,show that this phase shifter can provide a wide bandwidth from 1.36 to 4.53 GHz(107.6%)with a phase deviation of only±5°.Meanwhile,return loss better than 10 dB and insertion loss less than 1.25 dB can be obtained.(2)Based on microstrip line,a dual-band bandwidth-enhanced filtering phase shifter is proposed,which can achieve two different predetermined phase-shifting values with the single-layer structure.The proposed phase shifter is composed of two stub-loaded transmission lines(SLTLs)and two delay lines.The loaded stubs provide three transmission zeros to realize dual-band working and filtering function.Based on the even-and odd-mode network analysis,the theoretical formulas can be obtained.According to the theoretical analysis and design method,several dual-band phase shifters are achieved.A dual-band phase shifter example,which can provide the phase shift of 90° and 270° in two bands,is simulated,manufactured,and measured for demonstration.(3)Based on microstrip line,a single-layer symmetrical full-port quasi-absorptive filtering phase shifter is presented.The proposed phase shifter is composed of a main quasi-absorptive filtering branch,a reference quasi-absorptive filtering branch,and two delay lines.The proposed phase shifter achieves both phase controlling function and quasi-absorptive filtering function for the first time.Each quasi-absorptive filtering branch can realize the quasi-absorptive filtering function.Meanwhile,the constant phase shift can be obtained by combining the two quasi-absorptive filtering branches and the two delay lines.The design formulas can be derived from the even-and odd-mode network analysis,and then two quasi-absorptive filtering phase shifters can be devised easily and quickly.For verification,a 90° quasi-absorptive filtering phase shifter,which can be applied to circularly polarized antenna systems,is simulated,manufactured,and measured.(4)By employing dielectric waveguide(DW),miniaturized dual-band filters and filtering phase shifter based on multimode resonator(MMR)are presented.The single MMR(single cavity)is analyzed in detail.Based on the analysis of the single cavity,the proposed dielectric filters can achieve dual-band working with a miniaturized structure.For demonstration,two examples composed of two MRs are designed,manufactured,and measured.The measured results are in good agreement with the theoretical and simulated results.The measured results of the improved one with two transmission zeros(TZs)show that the manufactured DW filter can achieve an outstanding filtering function in both two bands with good outof-band performance.At last,the two DW filters are employed to compose a dual-band 180°/0° filtering phase shifter. |
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