基于极化转换的毫米波片上天线高效辐射机制研究

Aiming at the low radiation efficiency of the millimeter wave antenna on-chip based on the conventional CMOS process, this project proposes to use the idea of polarization conversion to solve the negative factors such as thin oxide layer and lossy silicon substrate, and makes a research on the method for significantly enhancing the radiation efficiency of the millimeter wave antenna on-chip. In the project, methods of surface phase abrupt and cross-polarization mutual inductance are utilized to study the ultrathin polarization conversion metasurface. Based on this metasurface, polarization directions of the transmitted wave and the reflected wave are separated to eliminate the reverse phase cancellation. In addition, by exploring the electromagnetic superposition problem of multiple reflections between the on-chip metal structures, the phase transitions and polarization conversions are revealed, and the design method of the metasurface will be modified. Finally, the radiation resonance condition for the superposition of different polarizations will be clarified. An antenna design method based on polarization conversion for high efficiency radiation will be proposed and verified by experiments. The research on high efficiency radiation mechanism of antenna on-chip developed by this project provides a new solution to overcome the radiation bottleneck of the millimeter wave antenna on-chip, and is of great significance for improving the performance of the next generation integrated-antenna module.

针对基于常规CMOS工艺的毫米波片上天线辐射效率过低的问题，本项目提出利用极化转换的思路克服CMOS工艺中过薄氧化层和损耗硅衬底等因素限制，研究大幅度提高毫米波片上天线辐射效率的方法。项目中，拟用表面相位突变和交叉极化互感等思路对超薄极化转换超表面进行研究，利用设计出的片上超表面结构，将发射波和反射波的极化方向分离，从而解决过近反射面造成的反相相消问题。另外，通过探索片上金属结构间多次反射的电磁叠加问题，揭示其产生的相变和极化转换规律，修正极化超表面的设计方法。最后，阐明不同极化的毫米波叠加后的辐射谐振机制，提出基于极化转换实现高效辐射的天线设计方法，进行实验验证。本项目所开展的片上天线高效辐射研究，为克服现有毫米波片上天线的辐射瓶颈提供了新的解决思路，对提高下一代集成化天线模块性能具有重要意义。

针对基于常规CMOS工艺的毫米波天线辐射效率过低的问题，本项目对基于CMOS栈层结构的超表面反射机制、超表面极化转换机制、高辐射效率的毫米波片上天线等关键科学问题进行了深入研究，突破了常规CMOS工艺栈层结构对片上天线的辐射限制，发展和验证了基于极化转换实现毫米波高效辐射的天线设计方法，完成了本项目的预定研究目标。本项目取得了如下主要成果：（1）建立了片上超表面的等效传输线模型，物理上解释了超薄超表面的失效机制和工作机制；（2）提出了超薄极化超表面的重叠阵列设计方法，在工作频段实现了高于94%的极化转换效率。（3）设计出了基于极化转换的毫米波片上天线，实验测试得到的辐射效率超过了60%，同时中心增益超过了7.4dB。在本项目的资助下，取得的研究成果部分体现于正式发表的6篇SCI期刊论文，以及申请或已授权的3项国家发明专利。相关研究成果已应用在实验室毫米波片上探测器的芯片设计中。