| The application of broadband technology in the field of wireless communication is of great significance.It can improve the utilization efficiency of spectrum resources and data transmission rate,and solve the problems of co-frequency interference.It is a relatively feasible way to solve the problem of increasingly tight spectrum resources,and thus it has become a research hotspot.The phase shifter,as a key component in communication antenna systems,imposes a bandwidth constraint on the entire communication system.Therefore,the research on broadband phase shifters holds significant academic significance.This paper studies the broadband technology of the microstrip phase shifter in feed networks,and the relevant research contents and innovations are as follows:(1)A comprehensive design method for parallel coupled broadband phase shifters is proposed.First,according to the relationship between the ABCD matrix and S parameters,the amplitude response and phase response polynomial of the phase shift network are extracted.Then,the equivalent circuit model of the parallel coupled structure phase shifter is established,and the circuit parameters in the equivalent circuit model are solved,and these parameters are mapped to the physical size.Finally,an efficient and accurate comprehensive design method of the parallel coupled structure phase shifter is established systematically,which can greatly improve the design efficiency of the phase shifter.(2)A design scheme of broadband miniaturized phase shifter based on parallel coupled line zigzag structure is proposed.First,the scheme proposes to use parallel coupled transmission lines and uniform transmission lines as the main line and reference line of the phase shifter.Then,the coupled transmission lines are bent into a "U" shape to make the entire phase shifter structure more compact,achieving miniaturization.Then,to verify the universality of the circuit design,circuit simulations were performed for multiple phase shift values,including 45°,90°,135° and 180°.Finally,a case with a phase shift value of 180° was designed and measured for the phase shifter,with a working bandwidth of 71.7% and a phase deviation of less than 4.5°.The proposed phase shifter has the advantages of simple structure,small size,wide bandwidth and convenient for integrated processing.(3)Aiming at the disadvantage that the parallel coupled structure is restricted by the coupling strength and cannot achieve a larger bandwidth,a design scheme of broadband phase shifter based on broadside coupled microstrip line is proposed.First,the scheme proposes to layer the λ/2 resonator with the feeder,and change the edge coupling to up-down coupling,thus greatly improving the coupling strength.Second,compared with the conventional phase shifter,the proposed scheme can significantly increase the coupling degree required in the design,thus achieving a wider operating bandwidth in a simple topology.Finally,a 90° phase shifter with a center frequency of 3GHz was designed,fabricated and measured,with an operating bandwidth of 80% and a phase deviation of less than 3°.(4)A design scheme of broadband phase shifter based on aperture-backed coupled microstrip line is proposed.First,the phase shifter forms two apertures on the metal floor by opening holes,which makes the medium under the coupling transmission line directly contact with the surrounding air,thus achieving the purpose of enhancing coupling.Then,through simulation verification,the influence of the length and width of different back aperture structures on the amplitude and phase response of the phase shifter is analyzed,and the contribution of the back aperture structure to the broadband of the phase shifter is further understood.Finally,a 180° phase shifter was designed,fabricated,and measured,with an operating bandwidth of 69.7%,a phase deviation of less than 5°,and an insertion loss better than 0.09 d B.Compared with the reported phase shifters,the proposed phase shifter has the advantages of simple structure,wide bandwidth and low insertion loss. |
