Novel metasurface technologies for coupling mitigation in antenna arrays

这项提案的重点是由辛克莱技术公司(Aurora，ON)制造的封闭式宽带偶极子阵列，其中包含四个偶极天线，工作频段从746 MHz到960 MHz。阵列沿单轴排列，组成偶极子通过大的中心到中心的距离分开，这导致了不幸的设计权衡：虽然希望紧凑，但天线阵列单元的紧密间距会导致一种称为互耦合的现象，这会损害天线阵列的增益；相反，最大化间距以减轻互耦合会导致天线结构过大。因此，当前的设计牺牲了一些收益，转而支持紧凑性。这些天线的适销性在很大程度上取决于它们的尺寸、重量、成本和增益性能，因此，重要的是设计策略，在不影响其增益性能的情况下最小化它们的尺寸，或者同等地，在给定尺寸的情况下提高它们的增益。拟议的研究重点放在第二种方法上，并试图通过使用电磁“亚表面”(MTSS)来减少通过天线辐射方向图中的旁瓣促进的有害互耦合。MTS是一种二维周期性结构，它以独特的方式与电磁波(如天线辐射的电磁波)相互作用，产生使用自然材料不可能或难以实现的现象。最近，艾伯塔大学(埃德蒙顿，AB)的Ashwin Iyer教授的研究小组开发了一种MTS技术，该技术由特殊设计的孔的周期性排列组成，这些孔具有允许MTS选择性地发射或反射信号的特性，这种特性可以被利用来在阵列环境中隔离天线，只需在它们之间放置一个或多个MTS。

The focus of this proposal is an enclosed wideband dipole array manufactured by Sinclair Technologies (Aurora, ON), which contains four dipole antennas operating over a frequency band from 746MHz to 960MHz. The array is arranged along a single axis and the constituent dipoles are separated by large centre-to-centre distances that result in an unfortunate design trade-off: whereas compactness is desired, close spacing of the antenna-array elements results in a phenomenon known as mutual coupling that compromises the gain of the antenna array; conversely, maximizing the spacing to mitigate mutual coupling results in an inordinately large antenna structure. As a result, current designs sacrifice some gain in favour of compactness. The marketability of these antennas is strongly dependent on their size, weight, cost, and gain performance, and it is therefore important to devise strategies to either minimize their size without compromising their gain performance or, equivalently, improve their gains for a given size. The proposed research focuses on the second approach, and attempts to reduce deleterious mutual coupling facilitated through sidelobes in the antennas' radiation patterns through the use of electromagnetic 'metasurfaces' (MTSs). MTSs are two-dimensional periodic structures engineered to interact with electromagnetic waves (such as those radiated by antennas) in unique ways resulting in phenomena that are either impossible or difficult to achieve using natural materials. Recently, the research group of Prof. Ashwin Iyer at the University of Alberta (Edmonton, AB) has developed a MTS technology consisting of a periodic arrangement of specially designed apertures possessing properties that allow the MTS to selectively transmit or reflect signals, a property that may be exploited to isolate antennas in an array environment simply by placing one or several MTSs between them.