**4.4 Diamond films for RF-MEMS application**

Diamond, DLC and DLN are potential materials for RF-MEMS applications. The RF-MEMS switches have potential for RF communications because of their high isolation and low power consumption. The RF switches, which usually based on electrostatic actuators. This RF switch can be used as diamond switch [69-73]. The boron doped diamond can be considered as semiconductor with wideband gap for fabricate the electronic device. Diamond materials are ideal candidate for RF power electronics where the important factors are like high speed, high power density, effective thermal management and passive matching components with low loss at microwave frequencies. So surface area is needed for passive component, active device, waveguide circuits and heat dissipation. The substrate needs for monolithic integrated RF power electronics in gigahertz frequency range. Leaky diamond films used in RF capacitive MEMS switches with low RF loss up to 65 GHz have excellent electronic properties of the diamond layers [74]. Leaky diamond mode can trapped the charges and eliminating the charge injection and increases the switches reliability. Fig. 17 shows the single anchored cantilever in coplanar waveguide for ON and OFF switching of microwave signals. Where the centre line is bridge by the switch need to content the contact in series. In the first figure (left side) the switch was staying perpendicular way on to the waveguide. This switching is quite low because of air damping [75-76]. The very large surface area can provide the high switching speed.

Fig. 17. Electrostatic actuators with coplanar RF waveguide. (a)The cantilever actuator closes a gap in a signal line from the side (left fig.) (b) The signal line is part of the beam itself (right fig.), ([52], permission to reprint obtained from John Wiley & Sons, Ltd.).

In right side of the figure where cantilever is the part of coplanar waveguide pattern. The RF line of ground plane act as a electrode of the parallel plate actuator [63].
