Research On Switch And Reconfigurable Antenna Based On MEMS Technology

Radio Frequency Micro-electromechanical System(RF MEMS)switches have properties of low power consumption,high isolation and low insertion loss.The reconfigurable antenna using RF MEMS switches can replace more than one antenna in the telecommunication system and it has the superiorities of the compact structure,light weight,etc.The key technologies of RF MEMS and reconfigurable antenna technology are the research hotpots.This dissertation focussed on the imperative requirements of high capacitance ratio MEMS switch and the reconfigurable antenna in the communication microsystem,and it met the challenges of the capacitance ratio enhancement of MEMS switch and radiation principles research of multi-patch pattern reconfigurable antenna integrated MEMS switches.This dissertation established the parameter calculation model of asymmetrical coplanar waveguide with defected ground structure(ACPW-DGS)and proposed the design methods of high capacitance ratio MEMS switch and reconfigurable antenna.Based on these methods,some kinds of MEMS switches and pattern reconfigurable antennas have been designed.The proposed models and methods were verified as well.The main research results and innovations of this dissertation are as follows.Firstly,for the problem of parameters quantification and calculation of ACPW-DGS,this dissertation established equivalent capacitance model and proposed the parameter calculation method based on the Schwarz conformal transformation and the first kind of non-complete elliptic integrals.Hence,the formulas were deduced for the ACPW-DGS parameters calculation.Secondly,this dissertation met the challenges of low capacitance ratio and long response time of capacitive MEMS switch with low elastic coefficient,and this dissertation researched the factors restricting the enhancement of the capacitance ratio.The four-S-type MEMS switch was designed based on metal-insulator-metal(MIM)floating metal electrode.The dielectric charging effect was alleviated and the capacitance ratio was enlarged.The measured results show that the dielectric charging effect was not appeared after 105 times test under high driven voltage,the capacitance ratio is 383.8 and the response time is less than 10μs.Thirdly,the design method of pattern reconfigurable antenna was deeply researched in this dissertation.This dissertation proposed two pattern reconfigurable antenna design methods based on the electric vector superimposition and based on the active element pattern and signal flow diagram,respectively.The pattern reconfigurable antennas were designed using the proposed methods.According to the testing results,two antennas can switch their pattern in the φ=90° plane between-17.2°,-0.6°,-1.5°,17.3°,and-0.2°,20.5°,-20.2°,-0.2°,respectively.The tested results have good agreements with the calculated results.The proposed methods not only decrease the size of reconfigurable antenna,but achieve multiple reconfigurable angle.Finally,this dissertation studied the pattern reconfigurable antenna array based on MEMS switches and designed the pattern reconfigurable antenna array.The fabrication process and testing schemes were also discussed in detail.