Electromagnetic Engineered Surfaces for Versatile Antennas

每日天气预报来自雷达，其天线波束连续扫描天空。同样，卫星通信系统需要扫描或调整其天线覆盖范围，以尽量减少干扰或修改其任务。这两个例子说明了需要具有波束可重构能力的大辐射孔径。目前提出的创新解决方案包括工程电磁表面（EES），反射器或透镜，嵌入电子相位调谐组件来控制波前。尽管半导体器件和MEMS具有非常快的响应，但它们在损耗和功率处理（非线性）方面受到限制。****提出的研究计划将研究一种不同的可重构机制，即带有机电致动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，所以它们的数量应该通过在副反射器或副透镜中使用来最小化。研究目标之一将是研究EES上执行器的数量与光束整形/扫描的可实现分辨率之间的权衡。本研究将以三个机电概念来完成，并将从射频性能和实际实施的容易程度方面进行调查。第一个概念是用微型马达旋转的反射镜。将开发逆相位合成方法，以确定有限尺寸EES的最佳相位分布作为所需天线方向图的函数，并使其适应所选的天线结构。第二个概念是一种可拉伸的磁膜，它可以用直流场来塑造，也就是用非接触式致动器。在这种情况下，由于膜成形和非均匀场中表面形状预测的限制，相位合成问题的难度增加了。第三个概念是基于加载机械改性材料的辐射导向介质中传播特性的变化。目标是将这一概念应用于雷达天线的仰角和方位角扫描。****该研究项目将在信息技术和通信（ICT）领域培养4名博士、4名硕士和2名本科生，重点是加拿大高科技产业的旗舰——航空航天应用。它涵盖了理论电磁分析，反问题的解决方案，模拟，和新的射频硬件设计，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.******