RF MEMS switches are one of the most promising future micro-machined products that have attracted numerous research efforts in recent years. This paper aims to propose an electrostatically actuated RF MEMS switch with reduced height. The switch is designed and optimized using an electrical and mechanical model. A single bridge switch employing torsion spring has been described to achieve high isolation of 40 dB at 10GHz frequency and low pull-down voltage. The results show that the proposed switch is suitable for various X-band applications including phased array antennas/radars, impedance matching circuits, transmitters/receivers, phase shifters, and so on. © 2011 IEEE.