Concepts for and Synthesis of Liquid Crystal-Tunable Ka-band Filters with Independently Tunable Center Frequency and Bandwidth

具有独立可调谐中心频率和带宽的液晶可调谐Ka波段滤波器的概念和综合

• 批准号: 424862129
• 负责人: Professor Dr.-Ing. Michael Höft
• 金额: --
• 依托单位: Lehrstuhl für Hochfrequenztechnik
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2019
• 资助国家: 德国
• 起止时间: 2018-12-31 至 2023-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/424862129?language=en
• 关键词: Concepts; Synthesis; Liquid; Crystal; Tunable

The number of radio services is steadily increasing with rapidly changing requirements in terms of frequency band allocation as well as bandwidth on demand. To meet these requirements, future communication systems such as satellites as well as 4. and 5. generation´s base stations, which have long operational times by implementation, require flexibility not only in the baseband, but also in the RF-frontend, e.g. by using reconfigurable components. A key component is the input filter. State-of-the-art are filter banks with a multitude of bandpass filters, which cover a plurality of parameters such as center frequency and bandwidth. The design is based on a fixed number of control states (i.e. filters) that can only be set discreetly and do not allow subsequent reconfiguration of filters or frequency band allocations. Furthermore, the large volume and weight of filter banks is a major problem especially for satellites. By using electronically controllable filters, parameters such as center frequency and bandwidth can be adjusted continuously within a certain tuning range. This allows an almost unlimited number of reconfigurations of the RF frontend. Furthermore, the volume and the weight of the filter is only a fraction of a filter bank. The primary objective of this research proposal is the analysis and synthesis of electrically-controllable liquid-crystal (LC) based filters reconfigurable in center frequency and bandwidth for satellite communication applications in the Ka-band. The LC technology, which had been established at TU Darmstadt provides two major benefits for the desired application in a satellite communication payload: (1) The liquid crystals have been optimized for millimeter-wave applications, showing very low losses, and thus, allowing a high filter quality. (2) Those liquid crystals are already space-approved, i.e. they are radiation hard, and therefore, suitable for the implementation into components of a satellite payload. The LC-filters to be synthesized in this project are controllable in center frequency as well as in bandwidth. Therefore, it is necessary to investigate different approaches for the realization of tunable coupling apertures and resonator structures. Suitable control electrodes are than developed with the aim to achieve the highest possible quality factor and a maximal tuning range. The LC-based higher order filter is than merged from individual investigated apertures and resonator geometries. The best suited filter topology is investigated using the coupling matrix approach. The fine tuning of the complete filter structure at the end of the synthesis process is done in a full-wave simulator. Therefore, the model has to be simplified in such a way that simulations can be accomplished in a suitable time. An investigation of the reconfiguration of the filter in operation mode as well as the implementation of a diagnosis algorithm for the realization of the thermal stability is provided at the end of this project.

随着频率频段分配以及按需带宽的需求，无线电服务的数量随着迅速变化的要求而稳步增加。为了满足这些要求，未来的通信系统，例如卫星以及4。和第5。世代基站（通过实施时间长期运行时间）不仅需要在基带上的灵活性，而且还需要在RF-Frontend中的灵活性，例如通过使用可重构组件。关键组件是输入过滤器。最先进的是具有多种带通滤波器的过滤库，涵盖了多个参数，例如中心频率和带宽。该设计基于固定数量的控制状态（即过滤器），这些状态只能谨慎设置，并且不允许随后重新配置过滤器或频段分配。此外，过滤库的大容量和重量是一个主要问题，尤其是对于卫星而言。通过使用电子控制的过滤器，可以在某个调谐范围内连续调整中心频率和带宽等参数。这允许几乎无限的RF前端重新配置。此外，滤波器的音量和重量仅是过滤器库的一小部分。该研究建议的主要目的是基于可控制的液晶（LC）过滤器的分析和合成，可在KA波段中用于卫星通信应用中的中心频率和带宽。在Tu Darmstadt建立的LC技术为卫星通信有效载荷中所需应用提供了两个主要好处：（1）液晶已针对毫米波应用进行了优化，显示出非常低的损失，因此允许高过滤质量。 （2）这些液晶已经被太空批准了，即它们是硬辐射，因此适合于卫星有效载荷的组成部分实施。基于LC的高阶滤波器的开发要比开发的，目的是达到最高的质量因子和最大调整范围。基于LC的高阶滤波器比单个研究的孔径和谐振器几何形状合并。使用耦合矩阵方法研究了最适合的滤波器拓扑。合成过程结束时完整滤波器结构的微调是在全波模拟器中完成的。因此，必须以一种可以在合适的时间内完成模拟的方式来简化模型。在本项目的末尾提供了对过滤器重新配置的投资以及实现热稳定性的诊断算法的投资。