RCS Reduction of Airborne Dispenser

The radar cross section (RCS) of dispenser and its components is computed by graphical electromagnetic computing (GRECO) method, which bases on physical optics (PO) method. A satisfied agreement is gotten between computed and measured results outdoor. The results show that the main scattering source of the dispenser is the mirror reflecting of the body; in the most crucial nose-on region, the nose mirror reflecting plays important role; the corner reflecting is important to the fins' RCS. The corresponding measures to reduce dispenser's RCS are proposed. It is indicated that to reduce RCS, shaping should be adopts first, while aerodynamic characteristics and stealth characteristics should be considered synthetically during the design of dispenser.     

一种RCS计算的新方法

给出了使用矩量法分析微带天线散射的方法,由于引入了附加模基函数,能够较准确地分析探针的作用.提出了使用两种不同负载的天线的散射场求天线接任意负载时天线的散射场的新方法,为快速分析微带天线的散射特性提供了理论基础.数值结果证明了这种方法的有效性.     

一种极化选择多频带的低雷达截面积反射屏简

A novel radar reflection screen composed of the polarization-dependent mutiband artificial magnetic conductor (PDMAMC) and perfect electric conductor cells is proposed. The PDMAMC is realized by etching a complementary split ring resonator (CSRR) on the patch of a conventional artificial magnetic conductor. Around the two/three operational frequencies of the PDMAMC-elements for different electric field polarizations, the reflection of the PDMAMC and perfect electric conductor have opposite phases, so for any normal incident plane wave the reflections cancel out. The basic principle is discussed and a sample is measured. The results show that the proposed method is feasible and effective for polarization-dependent mutiband RCS reduction.     

一体化雷达散射截面计算方法研究

针对传统RCS分析中，目标建模与RCS计算的分立状态，提出了一种一体化计算方法。将RCS图形算法集成到CAD造型软件中，为目标外形设计和RCS分析提供了一个完整的解决方案。计算实例说明，这种方法不但能够满足精度要求，而且可以极大地简化前处理工作，提高目标设计的总体效率。     

活动板类角反射器的RCS计算

利用几何光学和物理光学(GO+PO)的方法计算带有活动板一类角反射器的高频散射。给出了执行多次反射计算的一般流程,推导了计算多次反射的物理光学积分公式。对侧翻板型和上翻板型两种三面角反射器的雷达散射截面(RCS)进行计算,获得与测量结果较好的一致性。通过对常规三面角反射器和带活动板的三面角反射器后向散射特性的比较和分析,得出一些有利于优化设计的结论。     

用物理光学方法计算面元模拟涂覆体的雷达截面

给出了一种用物理光学方法计算面元模拟的电大尺寸涂覆体雷达截面的方法,导出了涂覆多边形平板散射场的物理光学计算公式．为验证该方法的有效性,给出了数值计算结果．     

高频区有表面波散射机制目标的RCS的预估

在高频区对有表面波散射特征目标的RCS的预估开展了研究。在利用可视化电磁计算技术得到目标镜面散射的基础上，补充表面波散射贡献，以对行波、爬行波贡献的计算提高有表面波散射特征目标的RCS的预估精度，通过实例计算，验证该方法具有工程计算的有效性，从而进一步拓宽可视化电磁计算方法的应用领域。     

一些低损耗介质圆柱双站RCS的矩量法分析

用矩量法对一些有于天线罩、电磁兼容设计的低损耗介电材料填充的无限长介质圆柱在TM波照射下的双站RCS进行了数值计算。仿真结果表明，相对于设计要求而言，低介电常数低损耗材料仍存在较明显的散射。散射与圆柱的电直径ka0的关系是：ka0较小时介电常数的实部ε‘起主要作用，ka0较大时介电常数的实部和虚部共同起作用。散射与双站角的关系是：双站角为0时散射最强，随着双站角的增大散射迅速减弱。     

一种用于飞行器RCS计算的高效矩量法

提出一种适用于飞行器隐身性能计算的高效矩量法。基于矩量法,通过分析物体几何外形与物面感应电流之间的关系,总结了几何形状对其表面电流分布影响的一般规律,在此基础上,根据物体表面各面元位置之间的距离、曲率等相对关系,提取物面单元感应电流间强耦合的阻抗矩阵元素,组成稀疏矩阵,并利用该矩阵计算物体的电磁散射。该方法保持了与传统矩量法基本一致的计算精度,而计算时间明显减少。以金属机翼模型和典型隐身飞机外形为例,计算结果表明该方法准确和高效。     

基于六边形AMC结构的60 GHz片上天线的设计

介绍一种基于六边形人工磁导体结构采用标准CMOS工艺的60 GHz片上天线的设计。标准CMOS工艺以金属硅为衬底,但衬底硅的低电阻率(10Ω·cm)和低的电子迁移率特性对天线辐射有较大影响。AMC结构通过合理的设计具有类似于理想磁壁的同相位反射特性。通过在天线与硅衬底之间周期加载AMC结构,可以有效地提高天线的增益、辐射效率等。重点讨论了采用人工磁导体结构的天线优化设计,并基于三维电磁仿真软件Ansoft HFSS仿真比较了不同排列的人工磁导体结构对天线性能的影响。     

基于通信卫星信号的星地双(多)基地雷达及关键技术

提出了一种基于通信卫星信号的非合作式星地双(多)基地雷达进行空中目标(隐身)探测的配置方案;分析了其基本原理及基本测量参量;探讨了实现基于通信卫星信号的非合作式星地双(多)基地雷达的关键技术。     

Antenna radar cross section reduction by a reconfigurable radar absorbing structure

An active reconfigurable Radar absorbing structure using a pin diode for the radar cross section (RCS) reduction of the antenna reflector is proposed, which is able to be switched between metal reflector with OFF-state diodes and absorber with ON-state diodes. The reflection coefficient of the RAS reflector is able to be switched between less than -25.0dB with OFF-state diodes and more than -0.8dB with ON-state diodes around 8.3GHz. The RAS reflector with ON-state diodes is applied to a dipole antenna reflector and gives radiation performance equivalent to that of the dipole with a metal reflector. The RAS reflector with OFF-state diodes is used as a radar absorber for RCS reduction. Meanwhile, a chessboard-like geometry RAS reflector is proposed in response to the wideband RCS reduction. The RCS reduction band covers the working band and is extended to 5～18GHz. The results show that the reconfigurable RAS reflector can contribute to the antenna RCS reduction at the working frequency, with the radiation performance of the dipole antenna preserved.     

基于人工电磁材料的新型电磁隐身机制——电磁隐身斗篷

电磁隐身是指通过缩减目标的散射截面来降低目标的可探测性。电磁隐身可大大提高武器装备的突防能力和生存率,在现代战争中具有极其重要的意义。2006年,英国物理学家Pendry等人提出了一种新型的电磁隐身机制——电磁隐身斗篷（Electromagnetic invisibility cloaks）,它突破了传统隐身技术的设计思路,使得“完全隐身”成为可能,引起了国际电磁学和光学界的广泛兴趣。首先介绍了电磁隐身斗篷的机理和研究进展,然后基于变换光学理论（Transformation optics）研究了任意形状隐身斗篷的理论设计方法,并给出了相应的数值仿真结果。     

利用高阻抗表面缩减天线雷达截面的新方法

针对现有雷达截面(RCS)减缩技术会导致天线辐射性能退化,体积、重量和成本增加,减缩性能受安装精度影响而不稳定的缺点,提出了一种缩减天线RCS的新方法．将高阻抗表面(HIS)与天线制作于介质板的同一表面,使HIS的同相反射相位带隙的频率与天线工作频率重合,通过高阻抗表面与天线的散射场的对消来减小天线的雷达散射截面,从而实现对垂直照射的天线工作频带内的同极化威胁雷达波的隐身．实验结果表明: 在天线工作频带内,其RCS得到了5.3dB以上的减缩,同时,带外RCS亦得到了有效的抑制,S₁₁的-10dB并未展宽,天线间的互耦得到了有效抑制．     

利用开槽和短路探针加载减缩微带天线RCS

提出利用开槽和加载短路探针等微带天线小型化技术,降低天线谐振频率,减小天线尺寸,抑制天线结构项散射从而实现天线雷达散射截面(RCS)减缩．在微带天线上应用此方法所得的仿真结果表明,使用该方法后天线工作频带内的RCS可降低4dB左右,而天线的增益下降不到0.4dB,从而保证天线的辐射性能的同时,明显地减小了工作频带内天线的雷达散射截面．     

Spatially dispersive model of wire medium for scattering

The electromagnetic properties of wire medium are studied by analyzing its transmission coefficient, and a homogeneous uniaxial effective permittivity tensor with one spatially dispersive component is obtained. In order to evaluate the validity of the equivalent model for scattering problems, the bistatic and monostatic radar cross sections (RCS) of a block of wire medium are investigated with the finite-difference time-domain (FDTD) method. The difference of RCS from the physical wire medium and the corresponding equivalent model has been compared and analyzed under various parameters of wire medium, which clearly demonstrates the accuracy of the equivalent model of wire medium.     

Volume integral method for calculation of weak scattering from electronically large dielectric targets

To calculate the high-frequency scattering fields from the weak scattering dielectric objects, starting with the vector and scalar wave equation separately,Born approximation and Rytov approximation are introduced to directly compute the radar cross section and extended to the high-frequency analysis of the electrical large weak scattering dielectric objects based on the volume integral equation. By weakening the mutual actions between the scattering field, the incident field and the total scattering field through this approximation, the complicated procedures for solving the matrix by the traditional method can be avoided, thus saving the computational resources and the time consumption. Numerical results show that the approach is accurate and effective.     

一种微带贴片天线RCS减缩新方法

为了减小微带贴片天线的雷达散射截面(RCS),利用电磁带隙结构(UC-EBG)的带阻特性,提出用UC-EBG代替普通金属作为微带贴片天线的地板．当天线工作频带内的电磁波入射时,UC-EBG地板呈现出带阻特性,不影响天线的正常工作;而在该频带以外,UC-EBG地板具有良好的带通特性,对入射电磁波起透射作用,从而可以达到减小天线带外RCS的目的．仿真和测量的结果吻合良好,证明了此方法的有效性．     

电大尺寸开口腔体的RCS计算和控制

通过对涂敷吸波材料的理想导体表面阻抗边界条件和反射系数的在薄涂层和大角度入射时的近似,结合物理光学近似得到了处理涂敷吸波材料腔体的物理光学迭代(IPO)公式．在此基础上采用初值继承算法和前后向迭代结合的快速IPO方法计算了采用S弯和在腔体内壁涂敷吸波材料对腔体雷达截面(RCS)的减缩效果．计算结果显示结合这两种方法可对电大尺寸开口腔体的后向RCS达到20dB的减缩作用．     

Application of metamaterial absorber for RCS reduction of slot antenna

An ultra-thin metamaterial absorber with polarization stability, a wide incident angle and no surface ullage layer is proposed and applied to the waveguide slot antenna to reduce its in-band Radar Cross Section(RCS). Theoretical analysis, and simulation and experimental results demonstrate that the absorber can exhibit an absorption of 99％ with thickness of only 0.0057λ, that when applied to the waveguide slot antenna in an optimized distribution, it can reduce the in-band RCS of the antenna for more than 3dB from -21° to +21°, that the largest reduction value exceeds 13dB in the normal direction, and that it can increase the gain by 0.99dB.