Low Actuation Voltage RF MEMS Shunt Capacitive Switch with High Capacitive Ratio

RF MEMS switches have found many interesting applications, especially in military and space-based technologies such as radars, antennas and satellites. In these systems, it is important to implement an ideal switch with high isolation, low power consumption, high power handling, low weight, low loss and low actuation voltage in a small size device. This paper presents an RF MEMS shunt capacitive switch with very low actuation voltage based on serpentine spring and low spring constant. The actuation voltage for three metal type including gold, aluminum and nickel are compared and the capacitive ratio is obtained for different dielectrics. The switch is designed on a coplanar waveguide line with an impedance of $\mathbf{50\Omega}$ . Using HfO 2 with $\mathbf{1000 \mathring{A}}$ thickness as a dielectric, the actuation voltage was obtained to be 3.2 V with a capacitive ratio (CR) of 260. Simulation results show that the proposed structure has an isolation of −37.63 dB, an insertion loss of −0.44 dB and a return loss of −26.46 dB at 24 GHz corresponding to good S-parameters.