Research On Phased Array Antenna Using 4-bit MEMS Distributed Phase Shifter

With absolute advantages in scanning speed and control flexibility, phased array antennas are widely used in radar, satellites and other modern communication systems, therefore, has been a hot area of research for several years. Phase shifter, one of the most important parts in phased array antenna, changes phase regularly so that the effective radiation pattern of the array is reinforced in a desired direction and suppressed in undesired directions, thus decides the performance of the phased array antenna.Nowadays,RF devices based on the technology of MEMS becomes more and more attractive in the communication field because of its advantages in miniaturization and integration. MEMS phase shifters are expected to have features of small size, low power consumption and better electrical properties. A large number of researches focus on structure optimization and technical innovation have been proceeded to obtain MEMS phase shifters with less return loss and finer phase precision.Based on fully analysis of working principle and modeling method, this thesis aims at designing a 4-bit X-band MEMS distributed phase shifter. The main work can be concluded as follows。 Get elementary structure and set electrical parameters of the distributed phase shifter by theoretical calculation. Finite element method(FEM) was applied to analyze the electromagnetic and mechanical properties of the basic unit of designed distributed phase shifter. Several structure adjustments were made to achieve lower loss and improve performance.A equivalent circuit model was built to assist analysis. According to simulation results, in the frequency range of 8-12 GHz,the average reflection loss of the distributed phase shifter designed is 15 dB, the average insertion loss is-0.6dB, and the average phase error is 1.5° with the minimum value of 0.9°. The driving voltage is 32 V and the response time is 1.6 μs. The detail processes of fabricating designed distributed phase shifter adopting MEMS technology is presented, along with critical processing steps, such as etching stop layer, discussed. The samples of distributed phase shifter were successfully obtained from MEMS laboratory.According to the measurement, the return loss of the phase shifter is-18.8dB, the insertion loss is-2dB. The phase error is 1° @22.5°and 3° @45°.