Electromagnetic Engineered Surfaces for Versatile Antennas

点击翻译按钮获取中文摘要

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.