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

[0218805]尽管目前的铱星和全球星以及拟议的Teledesic卫星系统存在经济和技术问题，但预计在不久的将来，基于卫星的高速互联网将成为现实。铱星和全球之星没有足够的带宽来容纳高速数据传输。不可否认的是，未来随时随地的高速互联网接入需要类似Teledesic提出的低地球轨道K或ka波段卫星系统。提出的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，低轨道卫星在10至20分钟内从一个地平线移动到另一个地平线。为了获得不间断的连接，天线必须能够跟踪一个或多个卫星的位置。这通常使用相控阵或机械操纵天线来完成。不幸的是，使用机电致动器的机械操纵天线通常体积庞大，容易发生机械故障。电子相控阵天线速度快，不涉及移动部件，但它们非常昂贵。他们的目标是开发一种使用新型移相器和电活性聚合物（EAP）致动器的低成本可操纵天线。为实现这一目标，项目主管部门提出了以下四项任务。任务1：利用EAP为相控阵天线开发一种低成本的移相器。任务2：设计一个实用的，低成本的相控阵天线。任务3：开发带有EAP驱动器的可变反射面天线。任务4：开发可靠和实用的EAP材料和执行器。移相器由传输线上的一个微小的机械可移动的介电元件组成。为了移动介电块，他们将使用新开发的EAP致动器，只需要1-2V。EAP执行器还可以用作微波开关，以创建可控延迟线。整个单元可以与贴片天线集成在多层PCB上。该天线不包含任何固态微波开关或机电设备。它的制造成本很低。他们已经对几种TL构型进行了数值模拟，并得到了结果。EAP致动器的另一个应用是用于机械操纵天线。柔性膜或板的轮廓可以用一组EAP致动器精确控制。通过调整表面轮廓，可以快速创建所需的辐射模式。实现基于eap的天线存在许多技术挑战。为了实现他们的目标，他们必须开发可靠的EAP材料和执行器。ppi认为，所提出的低成本天线将成为实现“空中互联网”的关键部件之一。虽然这种天线的许多方面已经经过测试和验证，但他们仍需要在一些细节上进行工作。EAP执行器仍处于婴儿状态。为了设计提出的天线，他们需要材料科学家（可以设计EAP执行器）和电气工程师（可以利用EAP执行器进行天线应用）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.