Design Of Liquid Metal Reconfigurable Antennas

In recent years,communication system evolved from the initial voice communication to video communication,from the original 2G to 5G,WLAN,and even 6G in the future.The communication technology has been extending rapidly,and the number and demand of the network users have increased sharply,thus the multifunctional integrated communication platform has been an inevitable trend.It is necessary to integrate antennas working in different states so that one platform can achieve multiple functions.However,when multiple antennas work on the same platform,the interference between the antennas will inevitably increase.Reconfigurable antenna means that the antenna can adjust its own performance according to requirements of the system.Compared with the traditional solid reconfigurable antenna,the advantages of liquid metal reconfigurable antenna are obvious.First,liquid metal can realize continuous tuning and the range is large.Second,liquid metal has a strong self-repair ability due to its fluidity,and it is not easy to be broken.Finally,when the antenna is not working,the liquid metal can be extracted,and the radar scattering interface of the liquid metal antenna can be greatly reduced.This thesis firstly introduces the basic theory of microstrip antennas,including microstrip antennas'definition,radiation mechanism,feeding structures and electrical parameters.Furthermore,three antennas are designed in this thesis:liquid metal frequency reconfigurable single-polarization antenna,liquid metal frequency reconfigurable dual-polarization antenna and liquid metal frequency reconfigurable array antenna.Finally,the liquid metal array antenna was fabricated and tested.The test results are in agreement with the simulated ones.The major contributions of the author are as follows:1.Liquid metal frequency reconfigurable single-polarization antenna is proposed.The antenna is engraved with an"H"slot on the floor.And there is a microfluidic rectangle groove in the upper substrate.The high-frequency and low-frequency switching is achieved by filling different solutions in the rectangular groove.In this design,gallium indium tin alloy?Galinstan?is used as liquid metal and Teflon is used as isolated solution.When the rectangular groove is filled with Teflon solution,the antenna operates at a high frequency,covering 3.55-3.81 GHz.When the rectangular groove is filled with liquid metal Galinstan,the antenna operates at a low frequency,covering 3.37-3.62 GHz.2.Liquid metal frequency reconfigurable dual-polarization antennas are researched.Based on the single-polarization antenna,the first dual-polarization antenna is proposed.The antenna is engraved with two"H"slots on the floor.And there is a microfluidic ring groove in the upper substrate PDMS.By filling Galinstan or Teflon solution in the groove,the frequency reconfigurable of the array antenna is achieved.In order to improve S₁₁,an"hourglass"shaped slot dual-polarization antenna is proposed.With the modified slot,the antenna can cover the requirements of bandwidth at both high and low frequencies with|S₁₁|<-14 dB.3.Liquid metal Frequency Reconfigurable array antenna is investigated.Based on the dual-polarization antenna,an array antenna which feed by a T-type power divider is proposed.It can cover the requirements of bandwidth at both high and low frequencies with|S₁₁|<-14 dB.Besides,the array antenna is fabricated and tested.The measured results are in agreement with the simulated ones.Compared with other liquid metal reconfigurable antennas,the array antenna has simpler structure,wider bandwidth,more stable directivity.And the frequency switching has little effect on the directional patterns.