Design And Application Of BST And PIN Tunable Phase Shifter

As a microwave component that can control signal transmission and cause phase change,phase shifter is widely used in electronic communication systems such as radar,phased array antenna,and digital mobile communication.With the maturity of new microwave materials and semiconductor processes,tunable phase shifters have developed rapidly.The discovery and research of ferroelectric materials have greatly promoted the development of analog tunable phase shifters.The new ferroelectric material barium strontium titanate(BST)has broad application prospects in tunable phase shifters because its dielectric constant can be adjusted by external electric field(dielectric tunability).At the same time,the PIN diode digital tunable phase shifter is the main product of the market,and has great practical value for production because of its high cost performance.In this paper,the problem of loading the coplanar waveguide interdigital capacitor structure and its application in the antenna array of BST thin film phase shifter was studied,and the S-band digital phase shifter was miniaturized.The main research works were shown as follows:1.The principle and key technologies of BST tunable phase shifter were studied.The coplanar waveguide type ferroelectric thin film phase shifter with interdigital capacitance was simulated by HFSS software.The effects of different structural parameters on the insertion loss and phase shift of the phase shifter were studied.2.The application of BST phase shifter in antenna array was studied.The BST thin film tunable phase shifter was applied to the 1×4 sector antenna array based on the optimization of the phase shifter performance.The BST thin film phase shifter was loaded in each radiating element,and the main beam direction deflection of the antenna array under different bias voltages was simulated.3.An S-band digital tunable phase shifter with a PIN diode as a control switch was studied.The principle of switch line type,load line type and reflective digital phase shifter was analyzed.Through the ADS simulation software,the miniaturization design of the 45° phase shifting unit was realized,and the physical production and verification were carried out.The cascaded simulation optimization of the 5-digit tunable phase shifter was performed.4.Based on the 3dB directional coupler of the 90° digital phase shifting unit,a useful attempt was made to study the miniaturization of the new type of translating coupler.The transmission line susceptance was adjusted by the method of loading the terminal capacitance,the coupler isolation was improved and the physical verification is performed.