Properties of Orbital Angular Momentum (OAM) Waves with Respect to Wireless Communication in Complex Environments and to Electromagnetic Interference

这里提出的项目旨在基于微波频谱较低部分（高达10 GHz）电磁波的轨道角动量（OAM）特性在无线通信领域做出科学贡献。OAM载波在过去主要在光学领域中被探索和使用。仅在大约10到15年前，才开始探索并且仍在探索在“无线电频率”上的无线通信的利用。虽然在这段时间期间可以表明OAM天线原则上等同于MIMO天线，并且因此不存在优于现有技术的真实的带宽优势，但是仍然存在许多与OAM波生成、传播和接收相关的公开的科学问题。在这个项目中探索的问题涉及基本的电磁观点（反射，衍射，散射，屏蔽，叠加/干扰等）。以及更应用的通信工程前景（单独的天线选择、阵列设计、模式隔离、阻抗匹配、有用的距离范围、带宽考虑、复杂环境和具有干扰源的环境中的行为等）。为了实现这一点，该项目提出了数值和实验方法的结合。将使用基于矩量法的内部工具进行数值模拟。与此同时，OAM天线的原型将在TUHH的天线测量室中设计和测试，其结果将与模拟结果进行比较以进行验证。项目的具体目标如下：（1）更好地理解和描述OAM波的基本电磁特性，如反射、衍射、散射、屏蔽、叠加/干扰以及在复杂环境中导致多径传播的行为。(2)生成OAM天线阵列设计的指导方针，包括单个天线元件的贡献以及阵列设计的贡献。(3)在复杂环境和电磁干扰下对基于OAM的通信进行量化和评估。(4)使用TUHH现有的天线测量系统开发OAM天线阵列和基于OAM的通信的测量程序，并验证选定的数值结果。我们相信，该项目的结果也将有助于进一步阐明基于OAM的通信是否具有更广泛的应用潜力的问题的实际工程方面。

The proposed project here aims to contribute scientifically in the area of wireless communication based on the Orbital Angular Momentum (OAM) property of electromagnetic waves in the lower part of the microwave spectrum (up to 10 GHz). OAM carrying waves have been explored and used in the past mostly in the optical regime. Only about ten to fifteen years ago utilization for wireless communication at “radio frequencies” started to be explored and is still being explored. While it could be shown during this time that OAM antennas are in principle equivalent to MIMO antennas and, hence, there is no real bandwidth advantage over existing technology there are still many open scientific questions related to OAM waves generation, propagation, and reception. Questions being explored in this project pertain both to the fundamental electromagnetic perspective (reflection, diffraction, scattering, shielding, superposition/interference etc.) as well as to the more applied communication engineering perspective (individual antenna choice, array design, mode isolation, impedance matching, useful range of distances, bandwidth considerations, behavior in complex environments and environments with aggressors etc.). To allow this, the project proposes a combination of numerical and experimental approaches. Numerical simulations will be performed an in-house tool based on the method of moments. In parallel, prototypes of OAM antennas will be designed and tested in an antenna measurement chamber at TUHH, the results of which will be compared to results of simulations for validation. The specific objectives of project are as follows: (1) Better understanding and description of fundamental electromagnetic properties of OAM waves such as reflection, diffraction, scattering, shielding, superposition/interference as well as behavior in complex environments leading to multi-path propagation. (2) Generation of guidelines for OAM antenna array design both with respect to the contribution from the individual antenna element as well as the contribution of the array design. (3) Quantification and evaluation of OAM based communication in complex environments and subject to electromagnetic interference. (4) Development of a measurement procedure for OAM antenna arrays and OAM based communication using an existing antenna measurement system at TUHH and validation of selected numerical results. We are convinced that the results of this project will also help to further elucidate the practical, engineering side of the question whether OAM based communication has the potential for a wider range of applications or not.