The Research And Design Of Reconfigurable Antenna Based On Liquid Metal

With the development of multi-frequency,multi-function and high integration of wireless communication system,the interference problem caused by multiple antennas on a platform can not be ignored.The traditional single antenna can not meet the needs of the system.Reconfigurable antenna,which integrates the advantages of multi-mode,small volume and high performance,has become a research hotspot in the field of microwave in recent years.Aiming at the key problems of wireless communication and satellite navigation,such as realizing multiple frequency polarization selection and flexible conformal at the same time,this thesis combines gallium based liquid metal with antenna technology,uses its fluidity and strong conductivity to experiment the control mode of liquid metal,and designs a variety of reconfigurable antennas.The main work is summarized as follows:1.The electric control experiment of liquid metal is carried out,and the mechanism of voltage control and mechanical control of liquid metal is explored.On this basis,a flexible monopole antenna is made by using liquid metal printer and flexible material.While changing its physical length by stretching,its|S₁₁|parameters are measured by vector network analyzer to explore the changes of radiation performance.Based on liquid metal,a frequency and polarization composite reconfigurable antenna fed by coplanar waveguide structure and applied in millimeter wave band is designed.A micro-flow channel is added above the square ring gap to switch between left-handed and right-handed polarization states by adjusting the position of liquid metal injection,while maintaining 12%3 d B axial ratio bandwidth,so that the antenna can be continuously reconfigurable in the range of 38 GHz-42.5 GHz.The antenna gain is greater than 2.5 d Bi and has good performance in the frequency band.2.Two frequency and polarization composite reconfigurable monopole antennas are designed.Firstly,a bent monopole antenna is designed to adjust the position and length of liquid metal injection to realize 7 kinds of frequency modulated bands in LHCP state,with a total 3 d B axial ratio bandwidth of 56.8%（2.96 ghz-5.31 GHz）.Then 8 kinds of frequency modulated bands in RHCP state,with a total 3 d B axial ratio bandwidth of 65.6%（2.91 GHz-5.75 GHz）.Then a monopole antenna loaded with parasitic spiral structure is designed to realize the switching of LHCP and RHCP polarization states and frequency reconfiguration.The 3d B axial ratio bandwidth is 68.9%.3.Two frequency and polarization reconfigurable cross dipole antennas are designed.Firstly,a polarization reconfigurable cross dipole antenna is designed based on the self phase shift structure.The switching of LP,LHCP and RHCP is realized by adjusting the liquid metal injection position.The impedance bandwidth of LP state is 19%（5.69 GHz-6.89 GHz）,and the 3 d B axial ratio bandwidth of LHCP and RHCP is 41.6%（4.11 GHz-6.27 GHz）and 29.3%（4.67 GHz-6.27 GHz）respectively.Then the phase-shifting ring ofλ/4 is used to design a frequency and polarization composite reconfigurable cross dipole antenna.The antenna can switch between LHCP and RHCP.The total 3d B axial ratio bandwidth is 49.2%（1.44 GHz-2.38 GHz）and 50.7%（1.43 GHz-2.40 GHz）respectively,and 8 adjustable circular polarization bands are obtained at the same time.