面向5G的低无源互调非接触连接器研究

Passive-intermodulation (PIM) interference is a kind of intermodulation noise caused by the undesired non-linearity when high power multi-tune signals pass through passive components. The “metal-metal” non-linear contact is one of the main sources of PIM interference of communication system. The traditional method of PIM suppression include: surface finish improvement, gold-or silver-plating, and contact pressure improvement, etc. These methods are of low-reliability and high-cost. In our proposal, a new method is proposed. The contactless electromagnetic bandgap (EBG) technology is introduced to the field of PIM suppression for the first time. This project will focus on the research on low-PIM contactless connector: Firstly, the “parallel-plate waveguide + periodic loading” contactless EBG analysis model should be established. The double-gapped contactless EBG theory would be developed from the traditional single-gapped contactless EBG theory. Secondly, the non-linearity performance of “metal-air gap-metal” model should be studied, especially the non-linearity performance versus the thickness of air gap when the contactless EBG structure is of rough surfaces. Thirdly, the design and experiment research on the film-style contactless low-PIM connectors. This project introduces a new method to develop connectors with low-PIM. The results of this project will help to reduce the PIM interference of the 5G communication system, and results in increased channel capacity and enlarged zone of signal coverage.

无源互调是无源器件大功率条件下非线性特性产生的多载波交调噪声，连接器的“金属-金属”接触非线性是通讯系统无源互调噪声的主要来源之一。抑制连接器无源互调电平的传统方法主要包括：提高接触面光洁度；采用金、银等惰性软质地金属进行表面涂镀以及提高接触面之间的压力等。这些方法稳定性有待提高且成本较高。本项目独辟蹊径，首次将非接触电磁屏蔽理论引入无源互调电平抑制这一研究领域，围绕低无源互调非接触连接器开展创新性研究，具体包括：1.建立 “平行板波导+周期加载”电磁带隙分析模型，将传统单间隙电磁带隙理论推广到双间隙；2.粗糙金属表面“金属-空气间隙-金属”非接触模型在不同空气间隙厚度下的非线性特性研究；3.开展膜片式低无源互调非接触连接器设计及实验研究。本项目为低无源互调连接器研制提供了全新的技术途径，研究成果将有效降低5G通讯系统的无源互调电平，提高系统的信道容量以及信号覆盖范围。

无源互调是无源器件大功率条件下非线性特性产生的多载波交调噪声，金属-金属、金属-氧化膜-金属接触非线性是通讯系统无源互调噪声的主要来源之一。本项目针对微波连接器无源互调干扰抑制难题开展研究，打破了通过提高接触面光洁度，采用金、银等惰性软质地金属进行表面涂镀以及提高接触面之间的压力等高成本、低可靠传统技术路径束缚，将非接触人工电磁带隙材料引入无源互调电平抑制这一研究领域。与传统方法相比，无源互调电平抑制度平均提高30dB, 且抑制水平不受连接力矩、表面涂覆条件的影响，尤其是不受铁磁性材料涂覆的影响。本项目重点研究了非接触人工电磁带隙材料技术和非接触低无源互调波导法兰技术，取得的标志性成果及主要创新点为：（1）提出了硬软表面非接触人工电磁带隙材料结构及其设计方法，解决了非接触人工电磁带隙材料结构强度低、不易加工的难题；（2）提出了交指钉床型、随机钉床型非接触人工电磁带隙材料，提高了人工电磁带隙材料设计自由度；（3）提出了硬软表面非接触低无源互调波导法兰连接器，实现了波导端口的非接触、低损耗、高可靠、高稳定、低无源互调互联；（4）提出了膜片式双间隙非接触法兰连接器，满足了传统波导法兰的非接触、低无源互调连接需求；（5）提出并成功研制了低无源互调微波传输线、低无源互调滤波器等低无源互调器件。本研究成果解决了微波电路金属接触非线性产生无源互调干扰的难题，相关科研成果，发表SCI论文2篇（中科院分区表一区论文1篇，二区论文1篇），获得国家发明专利授权5项。