Research On Reconfigurable Antenna Array Based On MEMS Technology

With the rapid development of wireless communication technology and the increasing demands of users,the requirements of various indicators of communication systems are becoming higher and higher.The antenna has the function of sending and receiving signals,which can realize the conversion of signals between electrical signals and electromagnetic wave signals,and is an extremely important part of the communication system.Modern communication systems require antennas to have the characteristics of miniaturization,strong anti-interference ability,and low power consumption.In order to meet the needs of modern communication systems,the reconfigurable antenna array based on MEMS technology has become a research hotspot.The directional pattern reconfigurable antenna array based on MEMS technology can realize the reconstruction of the radiation beam,so that one antenna can replace multiple antennas,which greatly reduces the system volume and improves the system integration.The reconstruction of the radiation pattern of the reconfigurable antenna array is achieved by MEMS switches.The MEMS switch changes the phase of the signal of the antenna unit by changing the mechanical structure of the antenna feed network,and finally realizes the reconstruction of the pattern.MEMS switches have the advantages of low power consumption,small size and high integration,and are widely used in communication systems.This thesis is mainly designed for the existing antenna array feeding network with high system complexity and inflexible output phase.The flexible output phase difference Butler matrix without cross coupler and phase shifter and reconfigurable Butler matrix based on MEMS phase shifter.Finally,the design of the reconfigurable antenna array based on the reconfigurable Butler matrix is completed.The research results and innovations of this paper are as follows:First,the traditional Butler matrix system is complex and the output phase is not flexible enough to limit the radiation range of the reconfigurable antenna array of the pattern.This paper designs a 4x4 Butler matrix model consisting of only four arbitrary phase difference couplers.Based on the proposed theoretical model,a Butler matrix with output phase difference of-30 degree,+150 degree,-120 degree and+60 degree is designed.Its isolation is-25 dB,return loss is-25 dB,amplitude imbalance is 0.2 dB,and phase error is 1 degree.The proposed Butler matrix has a simple structure and flexible output phase difference,so it greatly expands the application range of directional pattern reconfigurable antennas.Second,for the contradiction between the number of phase differences of the conventional Butler matrix and the low system scale,this paper proposes a Butler matrix topology based on a MEMS phase shifter.Its scale is the same as that of 4x4 Butler matrix,but it can achieve the same number of output phase differences as 8x8 Butler and 16x16 Butler matrix.Based on the theoretical model,this paper designs a reconfigurable butler matrix with 8 output phase difference and a reconfigurable butler matrix with 16 output phase difference.The isolation of the 8 output phase difference butler matrix is-25dB,the return loss is-25dB,the amplitude unbalance degree is 0.5dB,and the phase error is less than 1 degree.The isolation of 16 output phase difference butler matrix is-24db,return loss is-24db,amplitude unbalance degree is 0.5dB and phase error is less than 1 degree.Finally,based on the reconfigurable Butler matrix feed network,the design of a pattern reconfigurable antenna array based on MEMS technology is completed.Its radiation direction coverage is 65-degree,which can be freely switched between 8 beams.