# Design of Broadband High-Frequency Multi-Throw RF-MEMS Switches
## 3 Results and Discussion
### Current Density Distribution and S-Parameters  
Finally, to visually demonstrate the performance of our optimized switch, we present both the current density plot and the S-parameter graph. The current density distribution of the switch under its five typical operating states is illustrated in Figure 8. Distinctly, the red arrows unambiguously represent the direction of signal transmission; for instance, Model 1 signifies the signal transition from the input at port 1 to the output at port 4, with other models following a similar pattern. It should be underscored that, given the multitude of the switch's operating modes, symmetrical models are omitted for clarity. In the off state, there is a notable decline in current density at the disconnection region, reaching an almost negligible value. This minimal current characteristic endows the switch with superior isolation capabilities, ensuring the realization of high isolation levels. Conversely,  
Figure 6: Switch (a) return loss and (b) isolation curve under different \(g\) values.  
Figure 7: Power divider. (a) \(D1\) optimization; (b) \(D2\) optimization.  
the current density manifests a consistent distribution in the on state, facilitating a seamless current flow throughout the switch's entire structure. This not only ensures minimal insertion loss but also maintains signal integrity. Furthermore, this consistent current distribution substantially reduces the risk of hotspot formation and localized overheating, enhancing the switch's durability and operational stability.  
The Scattering parameters, commonly known as S-parameters, serve as essential tools in describing and assessing the electrical behavior of the switch in terms of its reflection and transmission properties. The S-parameter characteristics of the switch are presented in Figure 9, with Figure 9a depicting an insertion loss below 0.66 dB in the on state, Figure 9b showing that, for model 1, the return loss is less than \(-15\) dB across the entire working frequency range, reaching close to \(-43\) dB around 265 GHz, while the other modes have a return loss of less than \(-17.5\) dB across this range, and Figure 9c showcasing an isolation of more than 32 dB in the off state. These results underscore the switch's prowess in ensuring reduced signal attenuation, effective reflection control, and robust isolation in high-frequency and multifrequency scenarios. These performance metrics convey the ability of the signal to traverse the switch with minimal losses, ensuring negligible interference between ports. Such an attribute substantially reduces the potential for signal crosstalk and interference, enhancing overall signal transmission quality.  
The suggested packaging employs BCB glue and high-resistance silicon. Our simulation results indicate that the performance does not significantly fluctuate after packaging, as shown in Figure 10.  
Compared with prior research, Table 3 denotes that our proposed switch manifests significant advantages in multiple facets. Specifically, our switch offers a broader bandwidth, lower driving voltage requirements, faster response times, and superior signal isolation, rendering it a more competitive solution.  
Figure 8: Representative current density patterns of the switch in various operational modes.  
Figure 10: Switch S-parameters with packaging. (**a**) Insertion loss; (**b**) Isolation (average isolation across ports); (**c**) Return loss.  
Figure 9: Switch S-parameters. (**a**) Insertion loss; (**b**) Isolation (average isolation across ports); (**c**) Return loss.