Low-Cost Electrically and Mechanically Steerable Array Antennas for Internet-in-Sky Applications

尽管目前的Iridium和GlobalStar以及拟议的Teledesic卫星系统存在经济和技术问题，但基于卫星的高速互联网有望在不久的将来成为现实。Iridium和GlobalStar没有足够的带宽来适应高速数据传输。不可否认，未来随时随地的高速互联网接入需要与Teledesic提出的类似的低地球轨道K或Ka波段卫星系统。提议的Teledesic系统的主要问题之一是地面站天线和控制系统的成本。与地球同步卫星不同，低轨道卫星从地平线到地平线只需10到20分钟。天线必须能够跟踪一个或多个卫星位置，才能获得不间断的连接。这通常是使用相控阵天线或机械操纵天线来实现的。不幸的是，使用机电作动器的机械可操控天线通常体积庞大，容易发生机械故障。电子相控阵天线速度快，不涉及运动部件，但价格昂贵，其目标是开发一种使用新型移相器和电活性聚合物(EAP)作动器的低成本可定向天线。为了实现这一目标，PIS提出了以下四项任务。任务1：利用EAP开发低成本相控阵天线移相器。任务2：设计实用、低成本的相控阵天线。任务3：开发具有EAP致动器的可变反射面天线。任务4：开发可靠且实用的EAP材料和致动器。移相器由传输线上的微小机械可移动介质元件组成。为了移动电介质块，他们将使用一种新开发的只需要1-2V的EAP致动器。EAP致动器也可以用作微波开关，以创建可控的延迟线。整个单元可以与多层印刷电路板上的贴片天线集成。所提出的天线不包含任何固态微波开关或机电设备。它可以廉价地制造出来。他们已经进行了数值模拟，并得到了几种热释光构型的结果。EAP致动器的另一个应用是用于机械操纵的天线。利用EAP致动器阵列可以精确地控制柔性膜或板的轮廓。通过调整表面轮廓可以快速创建所需的辐射图案。实现基于EAP的天线有许多技术挑战。为了达到他们的目标，他们必须开发可靠的EAP材料和致动器。私人投资机构相信，拟议的低成本天线将是实现“空中互联网”的关键部件之一。虽然这款天线的很多方面都经过了测试和验证，但仍需在几个细节上下功夫。EAP执行器仍处于初级阶段。为了设计提议的天线，他们需要能够设计EAP致动器的材料科学家和能够将EAP致动器用于天线应用的电气工程师之间的密切合作。

0218805KugaDespite the economical and technical problems with the current Iridium and GlobalStar and proposed Teledesic satellite systems, it is expected that a high-speed satellite-based internet will become practical in the near future. Iridium and GlobalStar do not have sufficient bandwidth to accommodate high-speed transmission of data. It is undeniable that the future anywhere-anytime high-speed internet access requires low-earth-orbit K or Ka-band satellite systems similar to the one proposed by Teledesic.One of the major problems with the proposed Teledesic system is the cost of the ground station antenna and control system. Unlike a geo-synchronous satellite, the low-orbit satellites move from horizon to horizon in 10 to 20 minutes. The antenna must be able to keep track of one or more satellite locations in order to obtain an uninterrupted connection. This is usually performed using phased array or mechanically steerable antennas. Unfortunately, the mechanically steerable antennas which use electro-mechanical actuators are usually bulky and prone to mechanical failures. The electronic phased array antennas are fast and no moving parts are involved, but they are very expensive.Their objective is to develop a low-cost steerable antenna using a novel phase shifter and electro-active polymer (EAP) actuators. In order to achieve this objective, the PIs propose the following four tasks.Task 1: Develop a low-cost phase shifter for a phased-array antenna using EAP.Task 2: Design a practical, low-cost phased-array antenna.Task 3: Develop a variable reflector surface antenna with EAP actuators.Task 4: Develop reliable and practical EAP materials and actuators.The phase shifter consists of a tiny mechanically movable dielectric element ontransmission lines. To move the dielectric block, they will use a newly developed EAP actuator which requires only 1-2V. An EAP actuator can also be used as a microwave switch to create a controllable delay line. The whole unit can be integrated with the patch antennas on a multi-layer PCB. The proposed antenna does not contain any solid state microwave switches or electromechanical devices. It can be fabricated inexpensively. They have already conducted the numerical simulations and results were obtained for several TL configurations. Another application of the EAP actuator is for a mechanically steerable antenna. A profile of a flexible membrane or plates can be controlled accurately with an array of EAP actuators. A desired radiation pattern can be quickly created by adjusting the surface profile. There are many technical challenges to realize the EAP-based antenna. To achieve their objective, they must develop reliable EAP materials and actuators.The PIs believe that the proposed low-cost antenna will be one of the key components to realize the "Internet-in-the-Sky". Although many aspects of this antenna have been tested and verified, they still need to work on several details. An EAP actuator is still in an infant state. To design the proposed antenna, they need a close collaboration between a material scientist who can design the EAP actuator and electrical engineers who can utilize the EAP actuator for the antenna applications.