【作者】 吴磊；

【导师】 陈涌频；

【作者基本信息】 电子科技大学 ， 电子信息（专业学位）， 2023， 硕士

【摘要】 随着近现代通信科技的不断发展,人们对通信质量的要求愈来愈高。双极化天线由于其抗多径衰落、拓宽信道容量并有效降低馈电网络的复杂度等优势广泛被应用在无线通信系统中。不论是在基站通信系统还是在室内通信环境,都要求双极化天线覆盖更多通信频段的同时可以保持低剖面、小型化和高隔离。宽带特性能够避免使用多副窄带天线,使系统更为简单,高隔离指标则保证双端口的信号能够独立传输。对于双极化天线的实现方法,传统微带天线的带宽较窄,交叉偶极子天线与磁电偶极子天线又面临着剖面过高的问题。超表面天线的提出使得上述问题迎刃而解,超表面因其具有低剖面、低损耗、模式频率间隔较窄以及易于设计与实现的特点而广泛应用于天线设计中。本文基于超表面天线的形式,利用特征模分析的方法,对具有高性能的宽带双极化天线进行研究设计,主要工作如下:1.提出了一款双模宽带双极化超表面天线。对初始3×3超表面结构进行特征模分析,挑选出其中期望的正交模式,结合微带-缝隙耦合的馈电结构,将一对超表面模式与一对缝隙模式同时激励来拓展带宽,双极化端口的-10 d B相对带宽分别可达31.61%和32.77%,剖面高度仅为0.054λ₀,端口隔离大于25 d B。2.提出了一款多模宽带双极化超表面天线,此为第一款天线的延伸设计。首先确定了馈电方式及馈电位置,并结合指标要求提出对初始3×3结构的优化目标,通过特征模的分析找到期望的一对主模式与一对高次模式,再利用特征模的指导不断优化超表面的几何结构,改善高次模式的特性,最终将多对超表面及缝隙模式结合,实现了多模谐振下的宽带特性。测试双极化端口的-10 d B相对带宽分别可达52.08%和53.28%,端口隔离大于21 d B,天线具有稳定的侧向辐射特性,工作适用于Sub-6 GHz频段的5G基站系统。3.提出了一款全向高隔离宽带双极化超表面天线。基于初始4×4超表面结构,结合特征模分析选出其中的相互正交的全向垂直极化模式和全向水平极化模式,根据设计指标提出对超表面的优化目标,要保证模式谐振点相互靠近的同时最强电流的位置尽可能分离,两种模式再分别选用探针馈电和微带-缝隙耦合馈电进行激励,确保了较高的端口隔离,优化后的超表面满足设计需求。最终该天线实现了全向辐射特性,双端口的方向图不圆度低于3 d B,测试所得双极化端口-10 d B相对带宽约为39.4%,工作适用于室内近距离信号全覆盖的吸顶天线。更多还原

【Abstract】 With the continuous development of modern communication technology,the demand for higher quality communications is increasing.Dual-polarized antennas are widely used in wireless communication systems due to their advantages of resisting multipath decline,broadening channel capacity and effectively reducing the complexity of the feeding network.In both base communication station systems and indoor communication environments,dual-polarized antennas are required to cover more communication bands while maintaining low profile,miniaturization and high isolation.The wideband characteristic allows the use of multiple narrowband antennas to be avoided,which makes the system simpler.The high isolation ensures that the signals of two ports can be transmitted independently.For the implementation of dual-polarized antennas,conventional microstrip antennas have a narrow bandwidth and crossed dipole antennas and magnetoelectric dipole antennas are confronted with the problem of excessively high profile.The above problems can be solved by the introduction of metasurface antennas.Metasurfaces are widely used in antenna design because of their low profile,low loss,narrow modes frequencies spacing and ease of design and implementation.This thesis investigates the design of high-performance wideband dual-polarized antennas based on the form of metasurface antennas using characteristic mode analysis（CMA）.The main work is as follows:1.A dual-mode wideband dual-polarized metasurface antenna is proposed.CMA of the initial 3×3 metasurface structure is carried out to select the desired orthogonal modes within it.In combination with a microstrip-slot coupling feeding structure,a pair of metasurface modes and a pair of slot modes are excited simultaneously to extend the bandwidth.The-10 d B relative bandwidths of the dual-polarized ports can reach 31.61%and 32.77%respectively,with a profile height of only 0.054λ₀ and port isolation greater than 25 d B.2.A multi-mode wideband dual-polarized metasurface antenna is proposed.This is an extension of the first antenna design.Firstly,the feeding method and the feeding position are determined and the optimization objectives for the initial 3×3 structure are proposed according to the requirements.The desired pairs of main and higher-order modes are found based on CMA.Then the guidance of CMA is used to continuously optimize the geometry of the metasurface to improve the characteristics of the higher-order modes.Finally,the wideband characteristics under multimode resonance are achieved by combining multiple pairs of metasurface and slot modes.The measured-10d B relative bandwidths of the dual-polarized ports can reach 52.08%and 53.28%respectively,with port isolation greater than 21 d B.The antenna has stable broadside radiation characteristics.This work is applicable to the Sub-6 GHz band in 5G base station systems.3.An omnidirectional wideband dual-polarized metasurface antenna with high isolation is proposed.Based on the initial 4×4 metasurface structure,the mutually orthogonal omnidirectional vertically and horizontally polarized modes are selected in conjunction with CMA.According to the design requirements,the optimization goals for the metasurface is proposed to ensure that the modal resonance points are close to each other while the strongest currents are spatially separated as much as possible.Then,the two modes are excited by the choice of probe feeding and microstrip-slot coupling feeding respectively,ensuring a high level of port isolation.The optimized metasurface meets the design requirements.Eventually,the antenna achieves omnidirectional radiation characteristics.The un-roundness is lower than 3 d B for both ports.The measured-10 d B relative bandwidth of the dual-polarized port is about 39.4%.This work is suitable for ceiling antennas with full indoor signal coverage.更多还原