High actuation voltage is one of the most important limitations of RF MEMS switches. One way to reduce the actuation voltage is to reduce the spring constant in the switch structure.  In this paper, we model the spring constant using Energy Model and we obtain an analytic equation to calculate it. The result is an analytic design guide that determines the minimum value of the spring constant. Then, a new RF MEMS structure with very low actuation voltage is presented. The structure is modeled by the energy method and the spring constant is calculated analytically. Analysis results show the spring constant of 0.0714 N/m and an actuation voltage of 1.61 V. To evaluate the performance of the proposed structure and to validate the results of the analysis, a switch was designed using simulated COMSOL software. The results of this simulation show the actuation voltage of 1.8 volts, the switching time of 25.6 microseconds, the 4.5 MPa Von Mises stress, the natural frequency of 3118.6 Hz, its mass of 0.206 ng and finally the spring constant of 0.079 N/m. The beam is made of gold and Si₃N₄ is used as a dielectric. Finally, the high frequency performance of the switch is designed using simulated HFSS software. The simulation shows a 25 dB isolation, a 0.7 dB insertion loss, and a 16 dB return loss at 10 GHz.