Design And Research On RF MEMS Switches And Its Combining With Fractal Antenna

In recent years , an innovative electronic reconfigurable antenna (ERA) technology has been put forward. The optimized electronic reconfigurable antenna is a new and promising area of antenna design that alters the key antenna element properties (radiation pattern, polarization, radar cross section, tuning, and input impedance) in a non-mechanical but controlled manner. It is very important and significant that a multi-band and multi-mode electronic reconfigurable antenna can substitute several antennas, which have been used on some platforms, especially space based platforms, because the substitution can reduce the size, weight, and cost of the platform. At the same time, RF MEMS switch has found its great application in the area of wireless communications due to its small size, light weight, low power consumption and high isolation. Due to its nature-formed shape and well application, fractal antenna has been a hot point in recent research. When the fractal antenna combined with RF MEMS switches, the working field of the antenna will be changed and will give the antenna a multi-frequency characteristic.Firstly, the thesis analyzes the states in quo of the research on electronic reconfigurable antenna and RF MEMS switches.Secondly, the key measurements and the characteristics of two types of RF MEMS switches are given. The simulations are made by the software HFSS.Then, by using the software ADS, the equivalent circuits and the RLC parameters of the two types of switches are given. The detailed fabrication process is designed using surface silicon fabrication technologies. The suitable temperature and etching conditions of fabrication the sacrificial layer are given. Observations and researches are done to find the differences between BST film and ordinary film.In the last part of the thesis, the multi-band characteristics of antennas are discussed. The antenna is a bowtie antenna with the fractal of Sierpinski gasket. Combined with RF MEMS switches, the working areas of the antenna will be changed by the switches. The times of fractal and the on/off of the switches have great impact in the antenna's frequency bands.