Millimeter wave beam steering antenna platform for mobile 140 GHz wireless systems in hybrid Liquid Crystal - Nanowire Membrane technology

在过去十年中，无线接入系统对更高数据速率的需求不断增加，以满足不断增长的容量需求。这种对高带宽的需求不可避免地导致系统的工作频率增加到毫米波范围，其中仍然有大量的频率资源可用，特别是超过100 GHz。然而，功率链路预算的考虑和减少干扰和多径效应需要高增益窄波束天线。这些天线必须精确定位，以避免对准损失，这不是一件容易的事。此外，对移动通信系统的需求也在不断增加，与笨重的机械系统相比，电子波束控制能力将大大提高系统的性能，从而导致额外的高维护费用。然而，这是一个相当大的硬件和实现挑战，因为缺乏合适的低成本，可靠的技术用于可重构的毫米波组件，以及系统的波束转向率，功耗以及外形因素方面的特殊限制，考虑到紧凑性和平整度。在此背景下，项目的目标是(1)获得一种同时满足系统所有需求的新技术；(2)为进一步的系统实现建立一个创新的开发平台。对于这种方法，两种最近独立开发的技术将被合并，以实现相对于单个技术更高的功能和性能：(1)德国达姆施塔特工业大学的微波液晶（LC）技术，以及(2)法国UJF和巴西USP的金属纳米线填充膜（NaM）技术。使用慢波概念，小型、低姿态和高效率的无源电路将成为可能。基于微波液晶技术的移相器和开关等可调谐电路将受益于慢波概念与纳米线填充膜技术的结合。这允许小型化，将移相器安装到大约半波长平方的单个天线元件中，并且具有低轮廓结构的快速响应时间，这是最先进的微波液晶技术和组件的主要限制。为了进行概念验证和可行性研究，将在两个用例中构建一个系统级演示器，即140 GHz左右的d波段波束转向天线系统，并对其进行测试，以利用所进行的开发。它将由一个小尺寸天线阵列和一个复杂的馈电网络组成，包括巴特勒矩阵和开关元件以及移相器。该波束导向天线系统基于一种新概念，采用混合移相方法，将巴特勒矩阵的离散移相与液晶移相器的连续移相相结合，在140 GHz下实现了低损耗的大扫描范围。

In the last decade, demand has been increasing for higher data rates in wireless access systems to meet the needs for increasing capacity. This demand on high bandwidth leads inevitably to increasing operating frequencies of the systems up to the mm-wave range, where still large frequency resources are available, in particular beyond 100 GHz. However, power link budget considerations and the reduction of interference and multipath effects require high-gain narrow-beam antennas. These antennas have to be precisely oriented to avoid alignment losses, which is not an easy task. Moreover, an increasing demand is going towards mobile communication systems, where electronic beam-steering capabilities would increase the system´s performance dramatically compared to heavy and bulky mechanical systems, causing additionally high maintenance. However, this is a considerable hardware and implementation challenge, due to the lack of suitable low-cost, reliable technologies for reconfigurable mm-wave components and particular constraints in terms of systems' beam-steering rate and power consumption as well as form factor, taking compactness and flatness into account.In this context, the project aims (1) for a new technology, which meets all the system requirements at the same time, and (2) to build up an innovative development platform for further system realizations. For this approach, two recently and independently developed technologies will be merged in order to achieve higher functionality and performance with respect to the individual ones: (1) the microwave liquid crystal (LC) technology from TU Darmstadt, Germany, and (2) the metallic nanowire-filled membrane (NaM) technology from UJF in France and USP in Brazil. Small, low-profile and high-efficiency passive circuits will be possible, using the slow-wave concept. Tunable circuits such as phase shifters and switches based on the microwave liquid crystal technology will benefit from a slow-wave concept combined with the nanowire-filled membrane technology. This allows miniaturization, to fit the phase shifters into a single antenna element size of about a half-wavelength squared, and fast response times with low-profile structures, which are the major limitations of the state-of-the-art microwave liquid crystal technology and components.For a proof-of-concept and feasibility studies, a system-level demonstrator, a beam-steering antenna system in the D-band around 140 GHz will be built and tested in two use cases, in order to leverage the developments carried out. It will consist of a small-footprint antenna array and a complex feeding network, including Butler matrix and switching elements as well as phase shifters. This beam-steering antenna system is based on a new concept, using a hybrid phase-shifting approach, combining the discrete phase shift from a Butler matrix with the continuous phase shift from liquid crystal phase shifters to achieve a large scanning range with low losses at 140 GHz.