【作者】 李鑫；

【导师】 赵德双；

【作者基本信息】 电子科技大学 ， 无线电物理， 2024， 硕士

【摘要】 收发天线间的功率传输效率(Power Transmission Efficiency,PTE)是表征植入式微波无线传能(Microwave Power Transfer,MPT)系统性能的最重要参量之一。在植入式MPT系统中,植入式接收天线通常位于人体组织外部的发射天线近场区。此时传统MPT方法如远场方向图综合法在植入式MPT系统中已不再适用。同时电磁波在空气与人体组织接触的表面也会发生反射,即空气与人体组织之间的阻抗不连续,这也将导致PTE降低。此外,人体组织中复杂的电磁环境使得植入式接收天线的设计也变得困难。为此,本文设计了符合植入式MPT系统要求的单端口和双端口植入式接收天线,并基与此分析了植入式MPT中影响PTE的相关因素,同时设计了一种低剖面人工匹配层并结合时间反演幅相调控提出了一种高效植入式MPT方法。该方法可极大提高植入式MPT中的PTE,具有良好的应用前景。具体研究内容如下:首先,介绍了天线辐射原理以及植入式接收天线设计关键指标和方法、推导了植入式MPT中最优PTE和最优频率以及平面电磁波入射单层和多层人体组织时的电磁场,为后续设计、分析提供了理论基础。随后,基于植入式接收天线的辐射原理和关键指标,设计了一款小型宽频高增益的单端口植入式接收天线和一款共辐射体自隔离的双端口植入式接收天线,实测与仿真结果吻合。此外,也分析了人体组织色散特性和植入深度对植入式接收天线性能的影响以及它们在人体组织中的比吸收率和链路余量。然后,基于CST电磁全波仿真软件和所设计的两款植入式接收天线分析了植入式近场MPT场景中PTE的影响因素,包括收发距离、植入式接收天线的馈电端口数和位置偏移、发射阵元构型和数量对PTE的影响,确定了用于后续研究PTE提高方法的收发距离、植入式接收天线和发射阵元构型和数量。最后,设计了一款低剖面人工匹配层用以解决空气和人体皮肤之间的阻抗不连续的问题,并分析了人工匹配层阵元构型和数量对PTE的影响。同时,结合前述PTE分析结果,引入时间反演调控植入式近场MPT场景中发射阵元的幅相,并分析了此时PTE的变化情况。仿真结果表明,相较等幅同相激励,所提出的将人工匹配层阵列与时间反演相结合的方法可将PTE提高1倍以上。更多还原

【Abstract】 Power transmission efficiency(PTE)between transceiver antennas is one of the most important parameters to characterize the performance of microwave power transfer(MPT)systems.In an implantable MPT system,the implantable receiving antenna is usually located in the near-field area of the transmitting antennas outside the human tissue.At this time,traditional MPT methods such as far-field pattern synthesis are no longer suitable for implantable MPT systems.At the same time,electromagnetic waves will also reflect on the surface where air and human tissue contact,that is,the impedance between air and human tissue is discontinuous,which will also lead to the reduction of PTE.In addition,the complex electromagnetic environment in human tissues makes the design of implantable receiving antennas difficult.Therefore,this thesis designs a single-port implantable receiving antenna and a two-port implantable receiving antenna which meet the requirements of implantable MPT system.Based on this,the relevant factors affecting PTE in implantable MPT system are ana lyzed.At the same time,a low profile artificial matching layer is designed.Combined with time reversal amplitude-phase regulation,an efficient implantable MPT method is proposed.This method can greatly improve PTE in implantable MPT system,and has a good application prospect.The specific research contents are as follows:Firstly,the principle of antenna radiation and the key indexes and methods of implantable receiving antenna design are introduced,and the optimal PTE and frequency in implantable MPT system as well as the electromagnetic field when plane electromagnetic wave incident on single and multi-layer human tissue are deduced,which provides a theoretical basis for subsequent design and analysis.Then,based on the radiation principle and key index of the implantable receiving antenna,a compact broadband high gain single-port implantable receiving antenna and a common emitter self-isolated double-port implantable receiving antenna are designed.In addition,the effects of human tissue dispersion characteristics and implantation depth on the performance of implantable receiving antennas,as well as their specific absorption rate and link margin in human tissues were also analyzed.Then,based on the CST electromagnetic full wave simulation software and the two designed implantable receiving antennas,the influencing factors of PTE in implantable near-field MPT scenario were analyzed,including the influence of transmitter-receiving distance,the number of feed ports and position deviation of im plantable receiving antennas,and the configuration and number of transmitting array elements on PTE.The transmission and receiving distance,implantable receiving antenna and transmitting array configuration and number of PTE enhancement methods were det ermined by above analysis.Finally,a low profile artificial matching layer was designed to solve the impedance discontinuity between air and human skin,and the influence of the configuration and number of artificial matching layer elements on PTE was analyzed.At the same time,combined with the above PTE analysis results,time reversal is introduced to regulate the amplitude and phase of the transmitting array elements in the implantable near-field MPT scene,and the changes of PTE are analyzed.The simulation results show that the proposed method combining artificial matching layer array and time reversal can increase PTE by more than 1 times compared with constant amplitude in-phase excitation.更多还原