Modeling and Design of Reconfigurable Point Actuated Aperture Antennas

华盛顿为了满足21世纪的通信和广播需求，口径天线通常需要具有成形的表面，以便其辐射方向图有效地匹配要发送和接收信号的地理区域。这些天线通常是刚性的，由抛物面、抛物面、圆柱面、球面或双曲面形状组成。就现有技术而言，利用这些刚性结构的波束整形可以通过多个偏心馈电阵列或反射器表面(轮廓波束反射器天线)的非对称整形来实现。波束控制可以通过利用馈电阵列来电子实现，也可以通过使用专门设计的万向节倾斜整个反射器来机械实现。在星载等高波束反射面天线的情况下，一个主要的限制是刚性形状的反射面针对特定地理区域的覆盖进行了优化。一旦天线部署在轨道上，辐射方向图的修改就无法完成。随着卫星变得更加可靠，其预期使用寿命增加，卫星服务区域和/或运营商发生变化的概率也会增加。机械有源天线已经被提出作为解决这个问题的方案，但当时还没有商业上可行的单元。这样做的主要原因来自以下问题：1.我们有基于用户定义的辐射模式准确预测反射器形状的算法，但我们几乎没有处理真实结构的机制，更没有如何实现反射器的这些将动态改变其形状的偏转的机制。对于有源孔径天线的激励器数量、激励器位置以及最优激励器偏转等方面的基础性研究很少。目前还没有一种将电磁学与力学无缝耦合的基本机制，本研究提出的研究旨在有效地设计、建模和构造一种机械可重构天线来解决这些问题。由于这种类型的天线可以以传统相控阵天线总成本的一小部分来建造，因此也具有商业意义。例如，一家商业相控阵天线制造商声称，他们可以制造相控阵天线，每个元件的成本约为100.00美元。天基通信所需的分辨率从大约10,000到1,000,000个元素不等。这使总成本在(100万至1亿美元)之间。系统的重量和复杂性也会增加这一成本。如今，只需不到25,000美元，就可以用现成的部件建造一个机械可重新配置的系统。目前，全世界大约有600颗正在运行的卫星。到2010年，预计将发射多达1000颗新卫星，其中许多带有多天线系统。基于这一事实，很容易看到潜在的回报。设计和建造这些天线的基本方法将彻底改变今天这些口径天线的建造方式！

0100246WashingtonIn order to meet the communication and broadcasting needs of the 21st century, aperture antennas are generally required to have shaped surfaces so that their radiation patterns efficiently match the geographical regions where the signals are to be transmitted and received. These antennas are, in general, rigid and consist of parabolic, paraboloidal, cylindrical, spherical, or hyperboloidal shapes. In terms of the current state of the art, beam shaping with these rigid structures is possible with multiple off-center feed arrays or asymmetric shaping of the reflector surface (contour beam reflector antennas). Beam steering can be accomplished electrically by utilizing the feed array or mechanically by using specially designed gimbals that tilt the whole reflector. In the case of spaceborne contoured beam reflector antennas, a major limitation is the fact that a rigid shaped reflector is optimized for coverage of a specific geographical area. Once the antenna is deployed on orbit, radiation pattern modification cannot be accomplished. As satellites become more reliable and their expected service life increase, the probability that the satellite service area and/or operator will change also increases. Mechanically active antennas have been proposed as a solution to this problem, but at time there are no commercially viable units. The main rationale of this stems from the following issues:1. We have algorithms that can accurately predict reflector shapes based on user defined radiation patterns, but we have very few mechanisms that deal with real structures and even fewer for how to achieve these deflections for reflectors that will change their shape dynamically.2. There is very little fundamental research on how many actuators to use, actuator placement, and optimal actuator deflections for active aperture antennas.3. There is no fundamental mechanism for coupling the electromagnetics to the mechanics in a seamless fashion.The research proposed in this study seeks to effectively design, model and construct a mechanically reconfigurable antenna that addresses these issues. Since this type of antenna can be built at a fraction of the total cost of a traditional phased array antenna there is commercial significance as well. For example, a commercial manufacturer of phased array antennas claims that they can build phased array antennas at a cost of about $100.00 per element. The resolution needed for space based communications ranges from about 10,000 to 1,000,000 elements. This puts the total cost anywhere between ($1.0M-$100M). The system weight and complexity can also elevate this cost. A mechanically reconfigurable system can be built with off the shelf components today for less than $25,000. Presently there are roughly 600 satellites in commission throughout the world. By the year 2010, it is expected that up to 1000 new satellites will be launched, many with multiple antenna systems. Based on this fact it is easy to see the potential payoff. A fundamental approach to design and construction of these antennas will revolutionize the way these aperture antennas are built today!