Antenna analysis, design and measurement techniques

任何涉及无线通信的东西都需要天线，它是任何无线链路质量的关键。此举是为了提供多样化的服务，这些服务需要更高的数据速率，因此需要更大带宽的无线信道。这种对带宽的需求导致了可用频谱的饱和。因此，人们正在研究多输入/多输出（MIMO）和/或认知无线电技术，以通过改进电磁频谱的利用来提高未来无线网络的容量。所有这些发展都要求天线的功能大大提高。据估计，未来移动终端将需要20多个天线。然而，人们对更时尚、屏幕更大、电池更大的无线手机的渴望意味着天线的空间越来越小。因此天线的设计方法不能一劳永逸。手机的天线有宽波束，而无线基站、汽车雷达、成像系统和卫星通信的天线需要窄波束。为了达到所要求的性能，同时又不贵，这种天线必须使用印刷电路技术。处理增加的数据速率的一种方法是使用更高的工作频率，但在这些所谓的毫米波频率下，传统的窄波束（或等价地说，高增益）天线使用印刷技术变得效率低下。在低得多的频率上简单地扩展已经在使用的天线是不可行的。必须寻求替代配置。这些替代方案，如印刷透镜天线、反射天线和全息天线都是潜在的解决方案，但也有一些问题需要解决。在某些情况下，对单个天线处理许多不同任务的需求的唯一解决方案是使其可重新配置。例如，如果它的工作频率可以通过电子方式改变，它可以根据需要用于多个应用（在同一设备上）。也可能是天线能够改变其波束的形状或方向。本建议涉及开发能够满足上述更严格要求和限制的新天线配置。

Antennas are required in everything that involves wireless communications and are key to the quality of any wireless link. The move is towards the provision of diverse services that require higher data rates and hence wireless channels with larger bandwidth. This demand for bandwidth is leading to saturation of the available frequency spectrum. So multiple-input/multiple-output (MIMO) and/or cognitive radio techniques are being studied as ways to improve capacity in future wireless networks through improved utilization of the electromagnetic spectrum. All these developments require antennas with greatly improved functionality. It is estimated that in the future mobile terminals will need to have more than twenty antennas. Yet the desire for sleeker wireless handsets with larger screens and batteries has meant that there is less space for the antennas. So antenna design methods cannot be cut-and-try. Whereas antennas for mobile handsets have wide beams, those for wireless base-stations, automotive radar, imaging systems, and satellite communications need narrow beams. In order to achieve their required performance and yet be inexpensive, such antennas must use printed circuit technology. One way to handle increased data rates is to use higher operating frequencies, but at these so-called millimetrewave frequencies conventional narrow-beam (or stated equivalently, high gain) antennas made using printed technology become inefficient. It is not feasible to simply scale antennas already in use at much lower frequencies. Alternative configurations must be sought. These alternatives, such as printed lens antennas, reflectarray antennas and holographic antennas are potential solutions to the problem, but have issues that need to be resolved. In some cases the only solution to the demand for a single antenna to handle many different tasks is for it to be reconfigurable. For example, if its operating frequency can be altered electronically it can be used for more than one application (on the same device) as needed. Or it could be that an antenna is able to alter its beam shape or direction. This proposal is concerned with the development of new antenna configurations capable of satisfying the above tougher requirements and constraints.