Microelectromechanical Systems (MEMS) especially switches for Radio Frequencies (RF) are gaining high market potential from few years because of their excellent RF performance in different bands. Electromagnetic (EM) waves propagate in the switches through co-planar waveguides. Questions like optimised design parameters arises, when it comes to the designing of MEMS switches. In this paper, we have designed MEMS switches and optimised there design parameters. RF performance is simulated over a range of frequencies. E and H fields are also analysed for these switches to further optimize the response. It has been observed that the leakage occurs through the tip of the cantilever in series/ohmic switches thus reducing isolation of switch. Optimised design of these switches are presented that shows excellent RF performance. From the EM waves propagation patters, we have achieved higher performance than from commonly available switches. Comparison of RF performance is also given without the optimised design considerations. With the optimized designs we have achieved upto 24 % increase in isolation from 32 to 42 dB for L Band, 28 to 37 dB for S Band and 22 to 32 dB for C Band with almost 80 % reduction in pull in voltage requirements. The optimization techniques can be utilized for designing high performance RF MEMS switches.