Characteristic of plasma-based microstrip switch

A novel microstrip switch was developed based on micro-discharge plasma. The plasma switch is a dynamic device of microwave component to control the propagation of electromagnetic wave on the microstripline structure, which has a similar structure as RF MEMS switch but replacing its connecting anchor by using time-varying plasma. A basic structure of plasma switch contains a microstrip line with a small gap which is able to block electromagnetic wave and a discharge configuration which can generate a sheet-like plasma. When the discharge is turned on, the electromagnetic wave will transmit through the gap with the help of the conductive plasma, resulting in the ON state. When the discharge is extinguished, the electromagnetic wave energy will be reflected by the stripline gap, realizing the OFF state. The results from CST simulations show that the bandwidth of this plasma switch is determined by the plasma density, the isolation is determined by the microstrip structure and the gap itself, and the insertion loss is related to the plasma density and the electron-molecule collision frequency. The plasma structure (thickness, width, etc) is also important for the function of the plasma switch.