Electromagnetic Engineered Surfaces for Versatile Antennas

每天的天气预报是由雷达的天线波束连续扫描天空得出的。同样，卫星通信系统需要扫描或调整其天线覆盖范围，以将干扰降至最低或修改其任务。这两个例子说明了对具有波束可重新配置能力的大辐射孔径的需求。到目前为止，提出的创新解决方案包括工程电磁表面(EES)、反射器或透镜，嵌入电子相位调节组件来控制波前。虽然半导体器件和MEMS具有非常快的响应速度，但它们在损耗和功率处理(非线性)方面受到限制。拟议的研究计划将研究一类不同的可重构机制，即带有机电执行器的小型天线部件的物理运动。这些致动器虽然速度有限，但不与天线射频场相互作用，因此不会引入损耗和非线性。执行器也比半导体部件更笨重，需要更复杂的控制布线，所以应该通过在子反射器或子透镜中使用它们来最小化它们的数量。研究目标之一将是研究EES上的致动器数量与光束整形/扫描的可实现分辨率之间的权衡。这项研究将用三种机电概念来完成，还将从射频性能和实际实施的简易性方面进行研究。第一个概念是带有微电机旋转元件的反射阵列。将开发逆相合成方法来确定作为所需天线方向图的函数的有限大小的EES的最佳相位分布，并使其适应所选的天线体系结构。第二个概念是一种可伸展的磁膜，可以用直流场成形，也就是用非接触式致动器。在这种情况下，由于膜成形的局限性和非均匀场中表面形状的预测，增加了相合成问题的难度。第三个概念是基于加载机械改性材料的辐射引导介质中传播特性的变化。目标是将这一概念用于雷达天线的仰角和方位扫描。研究计划将培养信息技术和通信(ICT)部门的四名博士、四名硕士和两名本科生，重点是航空航天应用，这是加拿大高科技行业的旗舰。它涵盖了理论电磁分析、反问题解决方案、模拟和新型射频硬件设计、制造和测试。

Daily weather forecasts are derived from radars having their antenna beams scanning the sky continuously. Likewise, satellite communication systems need to scan or adapt their antenna coverage to minimize interference or modify their missions. These two examples illustrate the need for large radiating apertures with beam-reconfigurable capabilities. Innovative solutions proposed so far consist of Engineered Electromagnetic Surfaces (EES), reflectors or lenses, embedding electronic phase tuning components to control wave fronts. Although semiconductor devices and MEMS considered have very fast responses, they are limited in terms of loss and power handling (nonlinearity).The proposed research program will investigate a different family of reconfigurability mechanism, namely the physical movement of small antenna parts with electromechanical actuators. These actuators, although limited in speed, are not interacting with the antenna radiofrequency fields, and therefore do not introduce losses and nonlinearity. The actuators are also bulkier than semiconductor parts and require more complex control wiring, so their numbers should be minimized by using them in sub-reflectors or sub-lenses. One of the research goals will be to investigate trade-offs between the number of actuators on the EES and the achievable resolution of the beam shaping/scanning. This study will be done with three electromechanical concepts, which will also be investigated in terms of radiofrequency performance and ease of practical implementation. The first concept is a reflectarray with elements rotated with micromotors. Inverse phase synthesis methods to determine to optimal phase distribution of the limited size EES as a function of the desired antenna patterns will be developed and adapted to the chosen antenna architecture. The second concept is a stretchable magnetic membrane that can possibly be shaped with DC fields, i.e. with contactless actuators. In this case, the difficulty of the phase synthesis problem is augmented by the limitations of the membrane shaping and the prediction of the surface shape in a non-uniform field. The third concept is based on the change of propagation properties in a radiating guiding media loaded with mechanically modified materials. The goal will be to use this concept into a radar antenna scanning in elevation and azimuth.The research program will train four doctoral, four master and two undergraduate students in the Information Technologies and Communications (ICT) sector, with emphasis on aerospace applications, which is a flagship of Canadian high-technology industry. It covers theoretical electromagnetic analysis, inverse problem solutions, simulations, and novel radiofrequency hardware design, fabrication and tests.