Online Parameter Extraction and Control of Reconfigurable High-Frequency Filters

本课题的主要目标是研究高频滤波器的实时重构。为此，在输入新的目标特性之后自动执行微波滤波器的重新配置，并且补偿诸如温度漂移的各种影响。重新配置应在不中断信号路径的情况下进行，目的是开发平面和非平面技术的可调谐微波滤波器，并借助调谐系统影响传输特性。不同的调谐技术具有不同的非线性和品质因数。其中，它可以是具有变容二极管作为调谐元件的平面微带滤波器或具有机械调谐螺钉的同轴谐振器滤波器。在这些情况下，控制是通过可变电压源或步进电机实现的。该项目的一个重要方面是开发一个测量系统，以确定微波滤波器在运行过程中的传输特性。这里，过滤器结构不应断开，使得可能的传输不被中断。在应用程序中提出了潜在的方法，必须详细审查其优点和缺点。例如，可以在时域中研究信号，从而可以通过变换得出传递函数。随后，将研究不同的调谐算法，可以调整滤波器结构的传输特性。这些算法将根据运行时间和优化质量等各个方面进行比较。耦合矩阵提取提供了一种有效的调谐方法，但如何提供可靠和鲁棒的提取需要研究。基于散射参数和时域分析的重构算法被开发，以便调谐是可能的，而不需要构建一个等效电路。作为最后一个方面，人工神经网络将被研究，它可以用来重现未知的，甚至非常复杂的功能。最后，整个系统包括微波滤波器，控制电子，测量系统和调谐算法是建立和测试下的各个方面。一方面，当结构加热时发生的温度漂移将被补偿，另一方面，滤波器将被调谐到由新的中心频率和带宽组成的新的传输特性。

The primary goal of this proposal is to research the real-time reconfiguration of high-frequency filters. For this purpose, the reconfiguration of a microwave filter is to be performed automatically after the input of a new target characteristic and various effects, such as temperature drift, are to be compensated. The reconfiguration should take place without interrupting the signal path. The aim is to develop tunable microwave filters in planar and non-planar technology and to influence the transmission characteristics with the help of a tuning system. The different technologies for tuning have different non-linearities and quality factors. Among others, it can be a planar microstrip filter with varactors as tuning elements or a coaxial resonator filter with mechanical tuning screws. In these cases, the control is realized with variable voltage sources or stepper motors. An essential aspect of this project is the development of a measuring system to determine the transmission characteristics of the microwave filter during operation. Here, the filter structure should not be disconnected, so that a possible transmission is not interrupted. Potential approaches are presented in the application, which must be examined in detail for their advantages and disadvantages. For example, an investigation of the signal in the time domain would be possible, so that the transfer function can be concluded by transformation. Subsequently, different tuning algorithms will be investigated with which the transmission characteristics of the filter structures can be adjusted. The algorithms will be compared based on various aspects such as runtime and quality of optimization. Coupling matrix extraction provides an efficient method of tuning, but how to provide reliable and robust extraction needs to be investigated. Reconfiguration algorithms based on scattering parameters and time domain analysis are to be developed so that tuning is possible without the need to construct an equivalent circuit. As a last aspect, artificial neural networks are to be investigated, which can be used to reproduce unknown, even very complex functions. Finally, the overall system consisting of microwave filter, control electronics, measurement system and tuning algorithm is to be set up and tested under various aspects. On the one hand, the temperature drift that occurs when the structure heats up is to be compensated and, on the other hand, the filter is to be tuned to a new transmission characteristic consisting of a new center frequency and bandwidth.