CAREER: Microwave Variable Impedance Transmission Lines

本提案中描述的目标涉及用于实现电路元件的先进方法的开发和应用，这些电路元件是微波和毫米波组件设计的基础。研究的重点是新的微波传输线结构，其电学特性可以通过静电控制的调谐元件来操纵。通过消除对射频有源设备控制的需要，并结合微电子机械系统(MEMS)处理技术，这些生产线将为集成提供很大的自由度，并且本质上适合集成到MEMS微传感器设计中。相关的教育计划介绍了现代微波传感器系统的研究，通过早期世界的应用演示了微波和其他科学的结合使用。用于产生可调传输线的方法是将分布式线路等效为级联的、电小的串联电感-并联电容器(LC)对。在计划中的方法中，传输线部分将由LC对合成，每个LC对都包含微机械调谐元件。特性阻抗和传播常数是传输线的定义属性，可以使用这种新方法在较宽的调谐比范围内进行调整；一个现实的目标是实现20：1的阻抗比。调谐元件是单片的、静电驱动的微膜，在施加直流偏压下会弯曲。由于微波毫米波集成电路设计是基于分布式传输线技术，因此变阻抗传输线的潜在影响是显著的。从根本上说，设计匹配网络、滤波器、衰减器和耦合器的新方法是这些线路的可能用途之一。它们是有源(RF)设备控制的低功耗、本质上是无源的替代方案，因此是先进相控阵天线、集成传感器/通信系统和RF模拟/数字芯片等应用的使能技术。研究工作将集中于确定调谐元件和控制电极的最佳几何形状，以及它们在传输线配置中的应用。将解决与驱动电压、传播损耗、频率带宽和相位补偿有关的问题。这项工作将使用实验表征结合电路级和数值电磁建模来进行。该方法将在毫米波、可变匹配网络和衰减器的设计中得到演示。教育计划以开发传感器系统设计课程为中心。这门以项目为基础的高级课程将使用一个真实世界的微波传感器应用的案例研究作为每学期课程的重点。个别学生或两人小组将负责特定子系统的设计和开发，例如射频、通信和信号调节。本课程的一个重要特点是，每个传感器将与美国联邦研究中心或当地公司合作构思，这些研究中心或当地公司将提供相关的科学背景，协助系统架构设计，并管理传感器的实际现场部署。通过保持每个子系统的商业现成版本，并通过与合作者保持严格的学术联系，可以将开发风险降至最低。设计课程的目标是帮助学生学会如何学习，同时提供广泛的系统级工程应用。计划将课程材料转移到社区青年团体。*

9875235WellerThe objectives described in this proposal address the development and application of advanced methods for realizing circuit elements which are fundamental to microwave and mm-wave component design. The research focuses on new microwave transmission line architectures whose electrical characteristics can be manipulated using electrostatically-controlled tuning elements. By eliminating the need for RF-active device control, and incorporating microelectromechanical systems (MEMS) processing techniques, these lines will offer great latitude for integration, and are inherently fit for incorporation into MEMS microsensor design. The related education plan introduces the study of modern microwave sensor systems, through foal-world applications demonstrating the combined use of microwaves and other sciences.The methodology used to produce the tunable transmission lines derives from the equivalence of distributed lines to cascaded, electrically small, series inductor-shunt capacitor (LC) pairs. In the planned approach, transmission line sections will be synthesized from LC pairs, each of which incorporates micromechanical tuning elements. The characteristic impedance and propagation constant, which are the defining properties of the transmission line, can be adjusted over wide tuning ratios using this new approach; a realistic goal is to achieve impedance ratios of 20:1. The tuning elements are monolithic, electro-statically driven micromembranes which flex under applied DC bias. These geometries are readily fabricated using conventional integrated-circuit and MEMS processing techniques.As integrated microwave and mm-wave circuit design is based on distributed transmission line technology, the potential impact of variable impedance transmission lines is significant. Fundamentally new approaches to the design of matching networks, filters, attenuators and couplers are among the possible uses of these lines. They are a Iow-power, essentially passive alternative to active (RF) device control, and thus an enabling technology for applications such as advanced phased array antennas, integrated sensor/communications systems, and RF-analog/digital chips.The research efforts will concentrate on determining optimal geometries for the tuning elements and control electrodes, and on their utilization in the transmission line configurations. Issues relating to drive voltages, propagation loss, frequency bandwidth and phase compensation will be addressed. This work will be conducted using experimental characterization in combination with circuit-level and numerical electromagnetic modeling. The approach will be demonstrated in the design of mm-wave, variable matching networks and attenuators.The education plan centers on the development of a Sensor System Design course. This senior level, project-based course will use a case study of a real-world, microwave sensor application as the focus of each semester offering. Individual students, or groups of two, will be responsible for the design and development of particular sub-systems, e.g., RF, communications and signal conditioning. A significant feature of this course is that each sensor will be conceived in collaboration with a USF research center or a local company, which will provide the relevant scientific background, assist in system architecture design, and manage the actual field-deployment of the sensor. Development risks are minimized by keeping commercial off-the-shelf versions of each sub-system on-hand, and by maintaining a strictly academic association with the collaborators. The design course will pursue the objective of helping students learn how to learn, while at the same time providing a broad exposure to system-level engineering applications. Opportunities to transfer course material to community youth groups are planned.***