# Comprehensive Review of RF MEMS Switches in Satellite Communications
## 3 Strategies for Optimizing RF MEMS Switch Performance
### High Reliability
#### 3.1.2 Reducing Actuation Voltage  
Currently, many RF MEMS switches require high actuation voltages, often reaching several tens of volts. This high voltage requirement makes them less practical for applications like mobile wireless communication and reconfigurable circuits. Furthermore, high actuation voltages can lead to unstable dielectric behavior, limiting the switch's lifespan and reliability [90]. High actuation voltages also cause significant impact forces on the moving beams during contact, increasing the risk of mechanical failure. Additionally, high-impact forces can lead to bouncing and residual vibrations [94; 95]. Many researchers are working to reduce the actuation voltage of RF MEMS switches. Studies show that choosing optimal material properties and optimizing switch structural parameters are key to achieving low actuation voltage. The dynamic behavior of MEMS switches is largely influenced by squeeze-film damping, and introducing holes in the structural layer can mitigate squeeze-film effects [96]. Modifying and optimizing beam membrane structure to achieve a low spring constant can significantly reduce actuation voltage but may also reduce beam strength and affect reliability. There is also a trade-off between low spring constant and switch time. For example, reducing air gaps or increasing the area of the electrostatic field drive [97] increases the upstate capacitance, leading to RF signal loss. Electromagnetic, piezoelectric, and thermally driven MEMS switches have shown potential for low actuation voltages [98; 99; 27; 100]. Although these switches have successfully achieved low actuation voltage, they have disadvantages compared to electrostatically driven switches in terms of higher switch-driving power requirements and structural complexity. To address these issues, researchers have introduced hybrid actuation mechanisms, such as thermal/electrostatic, piezoelectric/electrostatic, and electromagnetic/electrostatic actuation. Table 1 shows some of the performances achieved by switches using these hybrid actuation mechanisms. In these schemes, switches are operated using electromagnetic, piezoelectric, or thermal actuation and maintained in their closed state electrostatically, achieving low-voltage operation and reduced power consumption. However, these schemes also introduce complexities in structure and slower switch speeds. Graphene, composed of carbon atoms tightly packed in a two-dimensional honeycomb lattice, exhibits excellent mechanical, thermal, and electrical properties, meeting the requirements for high-reliability contact materials, including high thermal conductivity, electromigration resistance, and fracture resistance. In recent years, graphene has attracted attention for its ultra-thin thickness, high Young's modulus of 1 TPa, and excellent current carrying capacity of 108 A/cm\({}^{2}\)[107; 108; 109]. In the application of NEMS/MEMS switches, graphene has shown its unique electrical and mechanical properties, attracting interest from many researchers. Studies have found that MEMS switches made of graphene can achieve a lower actuation voltage [110] and good RF performance [111]. [PERSON] et al. [112] first used graphene in MEMS devices. Mechanical exfoliation was used to extract single-layer and multi-layer graphene from graphite and place it on the groove of a SiO\({}_{2}\)/Si substrate to fabricate MEMS resonators, as shown in Figure 5a.