We present an analysis of graphene-loaded transmission line switches for sub-millimeter wave and terahertz applications. As such, we propose equivalent circuit models for graphene-loaded coplanar waveguides and striplines and examine the switching performance under certain parameters. Specifically, we identify the optimum design of graphene switches based on transmission line characteristic impedance, scaling factor, graphene shape, and topology (series or shunt). These parameters are varied to obtain the insertion loss and ON/OFF ratio of each switch configuration. The extracted results act as the design roadmap toward an optimum switch topology and emphasize the limitations with respect to fabrication challenges, parasitic effects, and radiation losses that are especially pronounced in the millimeter wave/terahertz bands. This is the first time that such an in-depth analysis is carried out on graphene-loaded transmission line switches, enabling the development of efficient millimeter wave/terahertz tunable topologies in terms of insertion loss and ON/OFF ratio. Specifically, the optimized switches can be integrated with antennas or employed for the development of tunable phase shifters, leading to the implementation of efficient reconfigurable reflective surfaces (e.g., reflectarrays) or coded phased arrays either for imaging or wireless communication applications. In our models, we use measured graphene values (sheet impedance) instead of theoretical equations, to obtain the actual switching performance. Moreover, the proposed study can be easily expanded to other thin film materials that can be characterized by a sheet impedance including vanadium dioxide and molybdenum disulfide. Finally, the proposed equivalent models are crucial for this in-depth study; since we simulated more than 2,000,000 configurations, a computationally challenging task with the use of full-wave solvers.

中文翻译：

---

晶圆上共面传输线的太赫兹石墨烯开关的建模与分析

我们介绍了用于亚毫米波和太赫兹应用的石墨烯负载传输线开关的分析。因此，我们提出了石墨烯共面波导和带状线的等效电路模型，并研究了某些参数下的开关性能。具体来说，我们根据传输线特性阻抗，缩放比例，石墨烯形状和拓扑（串联或并联）确定石墨烯开关的最佳设计。改变这些参数以获得每种开关配置的插入损耗和开/关比。提取的结果充当了朝向最佳开关拓扑结构的设计路线图，并强调了在毫米波/太赫兹频段上尤其明显的制造挑战，寄生效应和辐射损耗方面的局限性。这是首次在负载石墨烯的传输线开关上进行这种深入分析，从而能够开发出基于插入损耗和开/关比的有效毫米波/太赫兹可调拓扑。具体而言，优化的开关可以与天线集成在一起，或用于可调谐移相器的开发，从而导致为成像或无线通信应用实现有效的可重配置反射表面（例如，反射阵列）或编码相控阵。在我们的模型中，我们使用测得的石墨烯值（薄层阻抗）代替理论方程式，以获得实际的开关性能。此外，拟议的研究可以轻松地扩展到其他薄膜材料，这些薄膜材料的特征在于薄层阻抗，包括二氧化钒和二硫化钼。最后，提出的等效模型对于这项深入研究至关重要。由于我们模拟了2,000,000多种配置，因此使用全波求解器对计算具有挑战性。