Antenna analysis, design and measurement techniques

任何涉及无线通信的事物都需要天线，并且天线是任何无线链路质量的关键。这一举措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通道。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，以通过提高对电磁频谱的利用来提高未来无线网络的容量。所有这些发展都需要极大地改善功能的天线。据估计，未来移动终端将需要20多个天线。然而，对拥有更大屏幕和电池的更时尚的无线手机的渴望意味着，天线的空间更小。因此，天线设计方法不能是反复尝试的。移动手机的天线波束较宽，而无线基站、汽车雷达、成像系统和卫星通信的天线波束较窄。为了达到它们所需的性能，同时又不贵，这种天线必须使用印刷电路技术。处理数据速率增加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，使用印刷技术制造的传统窄波束(或相当于，高增益)天线变得效率低下。简单地将已经在使用的天线扩展到低得多的频率是不可行的。必须寻求替代配置。这些替代方案，如印刷透镜天线、反射阵列天线和全息天线是解决这一问题的潜在方案，但也存在需要解决的问题。在某些情况下，满足单个天线处理多个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电子方式改变，它可以根据需要用于多种应用(在同一设备上)。也可能是天线能够改变其波束形状或方向。该提案涉及能够满足上述更严格要求和约束的新天线配置的开发。

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.