【作者】 李毅；

【导师】 相征；

【作者基本信息】 西安电子科技大学 ， 军事通信学， 2022， 博士

【摘要】 随着现代武器装备信息化、智能化程度的大幅升级,电磁频谱已成为贯穿作战全域并产生跨域影响的资源型要素。在争夺现代战场的战略优势中,为破解目标对手日益强大的“反介入/区域拒止”能力,电磁频谱战概念被提出。电磁频谱战是敌对双方之间进行的电磁波斗争,即围绕着通信、雷达、导航、制导武器等辐射电磁波的武器装备所展开的电子侦察与反侦察、电子干扰与反干扰、摧毁与反摧毁的斗争。现代战争中,电磁空间的争夺越来越激烈,能否取得制电磁权对战争的进程乃至结局都将产生重大影响。电磁频谱战的出现,使得常规作战系统受到严重威胁和挑战,这对于作战系统的电磁防御能力和电磁波调控能力要求也越来越高。未来战场电磁环境复杂多变,武器装备面对电磁压制以及雷达探测时存在被干扰和摧毁的风险。本文着眼于提升武器装备生存能力的迫切需求,基于频率选择表面(Frequency Selective Surface,FSS)对电磁波相位、极化方式、传播模式等特性的灵活有效调控,从电磁抗干扰和雷达隐身两个方面入手,开展面向电磁防御的FSS设计与应用研究工作。在电磁抗干扰方面,目前的设计方法存在单元间易相互作用、图形设计复杂难以加工、对入射波角度敏感、紧密间隔特性差、频段不能独立调节、电磁波调控能力差等问题,从而影响FSS的应用效果。在雷达隐身方面,在FSS的基础上通过增加集总器件提出频率选择吸波器(Frequency Selective Rasorber,FSR)实现雷达隐身。但目前的设计方法存在传输性能和隐身性能无法兼顾、设计复杂、尺寸大、低频调控难以实现等缺点,成为限制其应用的主要因素。针对上述问题,为实现武器装备的电磁调控从而提升在战场复杂环境下的电磁防御能力,本文主要的研究工作可以概括为以下几点:(1)针对现有FSS结构面对电磁干扰时存在小型化程度不足的问题,提出/4中心旋转和枝节贯通的设计方法,设计出两种应用于不同场景下的新型双通带小型化FSS结构,能够增强带内信号的有效传输,减小带外干扰,进而提升电磁抗干扰性能。在第一种结构中通过对传统方环型缝隙和耶路撒冷型缝隙单元改进形成新型组合单元,该结构能够实现位于28.1GHz和39.5GHz处的双频传输带,且具有足够大的带宽能够覆盖第五代移动通信技术(5th Generation Mobile Communication Technology,5G)中的27.5GHz～28.35GHz和38.6GHz～40GHz频段,有助于提高未来军用5G高频设备抗干扰能力。相较于现有面向5G的FSS结构,本结构将单频滤波拓展至双频,在结构设计上将双层设计简化为单层设计从而降低结构复杂度;在稳定性上结构的入射角度可以从40°提升至45°;在小型化设计上结构厚度减小83.97%,单元尺寸减小1.1%。在第二种结构中基于矩形缝隙设计出新型阶梯型缝隙单元,该结构的两个传输频率分别为6.7GHz和18.1GHz,可以应用到处于C波段和K波段的卫星通信设备上。相较于现有面向卫星通信的FSS结构,本结构同样从单频滤波拓展至双频,并且将双层设计简化为单层设计,此外,厚度减小96%,单元尺寸减小54.34%。(2)针对现有FSS结构面对多频特别是紧凑频率的电磁干扰时紧密间隔特性较差的问题,提出交指互联和等距密集排布的设计方法,设计出两种分别具有双频/多频紧密间隔特性的新型FSS结构,能够实现在复杂电磁环境下对双频/多频屏蔽装置的应用。在第一种结构中设计出新型弓形环贴片单元,该结构具有双阻带特性和紧密间隔特性。相较于现有紧密结构,能够同时实现低谐振比、频段独立控制和小型化设计。在第二种结构中通过对“卍”字型缝隙、“井”字型缝隙、十字型缝隙和回字纹型缝隙改进形成新型组合单元,该结构具有三阻带特性,谐振点紧凑排列,分别位于S、C、X波段。相较于现有结构,滤波性能和稳定性保持一致,单元尺寸降低39.1%,厚度降低72.5%。(3)针对现有FSR结构在雷达探测时,对于长时间通电设备无法兼顾带内传输性能和带外隐身性能的问题,提出器件中心级联加载的设计方法,设计出一种新型吸透性能均衡的FSR结构,能够实现军用设备的隐身应用。在该结构中设计出嵌入式双弓形谐振器新型单元,滤波特性上表现为“吸波-透波-吸波(Absorption-TransmissionAbsorption,A-T-A)”。相较于现有结构,两侧吸波性能均衡,带宽均达到50%以上,单元尺寸至少降低8%以上,角度稳定性提升50%。此外,将梯度概念首次引入到FSR中,从而定义FSR结构的陡降特性,使得A-T-A型FSR结构的性能分析更加全面。(4)针对现有FSR结构在雷达探测时,低频设备频繁开关机需即时切换隐身模式的问题,提出拓展枝节和有源/无源器件协同加载的设计方法,设计出两种各具优势的应用于低频段的新型有源可控A-T-A型FSR结构,能够根据任务需求切换工作模式,从而在不影响任务完成的情况下实现隐身能力最大化。第一种结构是在第五章结构的基础上进行优化改进,通过加载正-本征-负(Positive-Intrinsic-Negative,PIN)二极管器件和对十字环缝隙卷曲枝节形成,该结构在实现低频可控的同时具有大吸波带宽,在通信模式下,为正常A-T-A型模式;在隐身模式下,结构为全吸波结构,即传统电路模拟吸波体(Circuit Analog Absorber,CAA)。为提升通信模式下的透射率,提出具有高透波率的低频可控FSR结构,在该结构中设计出嵌入式菱形谐振器新型单元,此结构尽管在吸波带宽上表现不佳,但在实现结构一功能的同时,通信模式下传输率可提升25.4%并实现降频。更多还原

【Abstract】 With the significant upgrade on informationization and intelligence of modern weapons and equipment,electromagnetic spectrum has become a resource-based element that runs through the whole field of combat and shows cross-domain influence.In the struggle for strategic advantage in the modern battlefield,the concept of electromagnetic spectrum warfare has been proposed in order to break the increasingly powerful ”anti-access/area denial” capability of the target adversary.The electromagnetic spectrum warfare is the electromagnetic wave struggle for the two sides of the warfare which is the struggle between electronic reconnaissance and anti-reconnaissance,electronic interference and anti-interference,destruction and anti-destruction around the weapons and equipment radiating electromagnetic waves,such as communication,radar,navigation,and guided weapons.The struggle is more and more fierce for electromagnetic space in modern war.Whether the electromagnetic right can be obtained will have a great influence on the process and even the outcome of war.With the emergence of electromagnetic spectrum warfare,conventional combat systems are seriously threatened and challenged,which requires more and more high electromagnetic defense capability and electromagnetic wave control capability of combat systems.The future battlefield electromagnetic environment is complex and changeable,and the weapons and equipment may be interfered and destroyed in the face of electromagnetic suppression and radar detection.This paper focuses on the urgent need to improve the survivability of weapons and equipment.The frequency selective surface(FSS)can flexibly and effectively regulate the characteristics of electromagnetic wave phase,polarization mode,propagation mode and so on.Starting from two aspects of electromagnetic anti-interference and radar stealth,the design and application of FSS for electromagnetic defense are carried out.In terms of electromagnetic anti-interference,the current design methods have some problems,such as easy interaction between elements,complex graphic design,difficult processing,sensitive to the angle of incident wave,poor tight spacing characteristics,non-independent frequency band and poor electromagnetic wave regulation ability which affect the application effect of FSS.In terms of radar stealth,FSR is proposed by adding lumped components to realize.However,the current design methods have some shortcomings,such as uneven performance,complex design,large size,and low frequency realization,which become the main factors limiting their application.In view of the above problems and in order to achieve electromagnetic control of weapons and equipment and improve electromagnetic defense capability in complex battlefield environment,the main research work of this paper can be summarized as follows:(1)Aiming at the problem of insufficient miniaturization for existing FSS structures in face of electromagnetic interference,the method of /4center rotation and branch penetration is proposed.Two new dual-passband miniaturized FSS structures applied in different scenarios are designed,which can enhance the effective transmission of in-band signals,reduce outof-band interference and improve the electromagnetic anti-interference performance.For the first structure,a new combination element is formed by improving the traditional square ring type slot and Jerusalem type slot.This structure can realize the dual band transmission at 28.1GHz and 39.5GHz,and has a large enough bandwidth to cover 27.5GHz～28.35 GHz and 38.6GHz～40GHz bands of 5G,which will help improve the anti-interference capability of future military 5G high-frequency equipment.Compared with the existing 5G-oriented FSS structure,this structure extends single-frequency filtering to dual-frequency filtering,simplifies layer design to reduce the structural complexity.In terms of stability,the incident angle can be increased from 40° to 45°.In terms of miniaturization,thickness is reduced by83.97% and unit size is reduced by 1.1%.For the second structure,a new step-type slot element is designed based on rectangular slot.The two transmission frequencies of the structure are 6.7GHz and 18.1GHz respectively,which can be applied to the satellite communication equipment in the C-band and K-band.Compared with the existing FSS structures for satellite communication,the proposed structure also extends from single frequency filtering to dual frequency filtering,and simplifies layer design.In addition,the thickness is reduced by96%,and unit size is reduced by 54.34%.(2)Aiming at the problem that the existing FSS structure has poor tightly spaced characteristics when facing multi-frequency electromagnetic interference,especially compact frequency electromagnetic interference,the method of interdigital interconnection and isometric dense arrangement is proposed.Two new FSS structures with tightly spaced dualfrequency/multi-frequency characteristics are designed,which can realize the application of dual-frequency/multi-frequency shielding devices in complex electromagnetic environment.For the first structure,a new arched ring patch element is designed which has the characteristics of double stopband and tightly spaced.Compared with the existing compact structure,it can simultaneously realize low resonant ratio,independent control of frequency band and miniaturization design.For the second structure,a new combination element is formed by improving the swastika slot,well slot,cross slot and back slot.This structure has three stopband characteristics,and the resonant points are tightly spaced that located in S,C and X bands respectively.Compared with the existing structure,this structure shows that the unit size is reduced by 39.1% and the thickness is reduced by 72.5%.(3)Aiming at the problem that the existing FSR structure can not take into account the inband transmission performance and out-of-band stealth performance when the device is powered on for a long time,the method of device center cascade loading is proposed.A novel FSR structure with balanced absorption and transmission performance is designed to achieve stealth applications in military equipment.A new type of embedded double bow resonator element is designed and its filtering characteristics are A-T-A.Compared with the existing structure,the absorption performance of both sides is balanced that the bandwidth is more than 50%,the unit size is reduced by 8% at least,and the angular stability is increased by50%.In addition,the gradient concept is introduced into FSR for the first time to define the steep drop characteristic of FSR structure,which makes the performance analysis of A-T-A FSR structure more comprehensive.(4)Aiming at the problem that existing FSR structure needs to instantly switch stealth mode in the face of frequent switching on and off of low-frequency equipment during radar detection,a new method of expanding branches and co-loading with active/passive devices is proposed.Two new active controllable A-T-A FSR structures for low frequency applications are designed,which can switch operating modes based on mission requirements to maximize stealth capability without compromising mission completion.The first structure is optimized and improved on the basis of the structure in Chapter 5,which is formed by loading PIN diode device and crimped branch of cross ring slot.The structure can control the low frequency and has large absorption bandwidth.In the communication mode,it is the normal A-T-A FSR.In the stealth mode,the structure is a full absorber structure which is a traditional CAA.In order to improve the transmittance in communication mode,a low frequency controlled FSR with high transmittance is proposed.In this structure,a new type of embedded diamond resonator element is designed.Although the performance of the proposed structure is poor in absorption bandwidth,the transmission rate can be increased by 25.4% in the communication mode and transmission frequency can be reduced while realizing the function of the first structure.更多还原