A Study Of Reconfigurable Antennas Based On Liquid Metal

Along with the increasing demands for information interaction nowadays,the requirements for multifunctional antennas are becoming a research hot.Different from traditional rigid metal antennas with fixed shapes,any deformation like bending,meandering and folding,would cause a deterioration in performance,the liquid metal EGa In alloy possessing with liquidity at room Temperature and excellent electrical conductivity,makes it possible for the design of reconfigurable liquid metal antennas.Combined with EGa In alloy,three types of antenna with different reconfigurable functions have been designed in this thesis.A frequency reconfigurable antenna has been designed in X band.By loading an open annular slot on a patch antenna,a new resonant based on TM₂₀ mode has been added,renders this antenna a dual-band characteristic.Controlling the liquid metal in the microfluidic channels,the length of the slot can be varied below,then the operating band of this antenna can be shifted.The overall profile of this antenna is 1.575 mm(4.2%?).Optimized by software HFSS,the reconfigurable frequency range of antenna(|S₁₁|<-10 dB)is within 7.23to 10.06 GHz(35.3%),without significant change in the radiation pattern.A circular polarization reconfigurable antenna has been designed in GPS band.By crosswising two linearly polarized inverted F antennas,a circular polarization radiation characteristic can be achieved.Respectively loading liquid metal into the dielectric containers at each ends of the two stubs,which makes this antenna a reconfigurable circular polarization rotation.Only one feed point and one shorting-stubs are designed for simplifying purpose.What's more,coupling feed and a stripline have been applied for improving the port matching.Optimized in software HFSS,the impedance bandwidth(|S₁₁|<-10 dB)of this antenna is within 1.54 to 1.63 GHz,and the 3 dB Axle ratio(AR)bandwidth is within 1.57 to 1.59 GHz when the antenna is in the right-handed circular polarization state.The Impedance bandwidth(|S₁₁|<-10 dB)of this antenna is within 1.54 to1.63 GHz,and the 3 dB Axle ratio(AR)bandwidth is within 1.56 to 1.585 GHz when the antenna is in the left-handed circular polarization state.A pattern reconfigurable Yagi-Uda antenna based on liquid metal is presented,which works in the WLAN band.The antenna consists of a balun-fed active dipole and a pair of stretchable passive parasitic dipoles,which are implemented by EGa In alloy embedded in microfluidic channels.The parasitic dipoles are driven at each end by two low-cost,3-D printed media rods.Afterwards,spinning the rods at different angles leads to varying degrees of stretching upon the stretchable dipoles.Note the length of passive parasitic dipoles is a vital factor for antenna radiation reconfiguration.The antenna exhibits bidirectional radiation if the parasitic dipoles are equal in length.Otherwise,directional radiation towards the shorter parasitic dipole direction can be obtained.Based on the above-mentioned working principle,a pattern reconfigurable antenna working in WLAN band is fabricated and measured.Apart from the reconfigurable capability,the proposed antenna keeps operating in the WLAN band of 2.4to 2.48 GHz during the whole shape deformation.