In this paper , the emphasis is the application of the fdtd arithmetic in slot ' s scattering . this method modifies incidence wave and the reflected wave from conducted plane , and that result in the fdtd scattering formulations are only about the scattering field of slot 论文重点研究了fdtd算法在无限大导电平面上缝隙的散射计算中的应用，该算法对入射波和平面反射波进行了处理和修正，最终，在fdtd散射公式中只计算缝隙的散射。
For the scattering field caused by the finite - length conducting and permeable cylinder , the boundary condition that the normal component of electrical strength is zero in conducting medium , i . e . en = 0 , was used to determine the separation constant of boundary value problem in the past 以往含有有限长导电导磁圆柱体散射场的求解，大都根据导电媒质中电场强度法向分量为零，即e _ n = 0 ，这一边界条件来确定边值问题中分离常数的取值。
The rain area is regarded as a random background medium , and the scattering field and backscattering matrix of the cylinder target in rain are gained . in the coherent case , the power of cylinder target in rain and air and their optimum polarization states are studied by the three - step method 在研究雨中目标时，本文把雨区看成随机的背景介质，利用波传播理论、目标的边界条件，得出介质圆柱在雨中的散射场、后向散射矩阵，并进行了相关计算。
With the plane wave representation of the green ' s function , the second - order scattered coefficients are divided into two components related to the coincidental waves and the anti - coincidental waves , which are dependent on the relationship between the single scattered field and its conjugate 通过将格林函数做平面波展开的方法，二阶散射系数分解成与同向波和反向波有关的两部分，同向和反向分别是按单次散射场和其共轭场的耦合方式而划分的两种不同情况。
The algorithm only needs to solve an ill - posed linear system and a well - posed minimization problem and requires only the knowledge of the near field measurements of the scattered fields due to point source fields at a finite number of incidence and observation points distributed over a limited aperture 该算法只需求解一个不适定的线性系和一个适定的非线性最小化问题，而且只需要点源入射场的散射场在某个有限孔径中若干有限个入射和测量点上的近场测量信息。
The material ways are to model the honeycomb wall as an impredence surface , to express the infinite honeycomb by using periodic green ' s function , and using method of moment to establish the mathematic model , in applying the methods of moments , we choose the roof function as basic function and choose the razor function as test function ; by equating the incident field to sum of the scattering field and impledance field ; we will set up the integral equation for the surface current , solving it by mom equation . then gain it ' s reflected coefficient ' s numerical result . and we propose first the definition of the equivalent electromagnetic parameters and present a method to calculate them from the gained reflection coefficient 具体方法就是将浸渍吸收剂的蜂窝壁用表面阻抗表示，将无限大的周期结构的电场用周期格林函数来表示，选取有耗蜂窝结构中具有代表性的基本计算单元应用矩量法建立数学模型,在运用矩量法时用屋顶函数作为基函数，刀片函数作为检验函数，根据蜂窝壁表面电场必须满足入射电场等于散射电场和阻抗电场之和的规律，推导表面电场积分方程，求解蜂窝结构的表面电流，利用蜂窝的周期规律得到无限大均匀周期阵列的散射电场。
In the first part , the basic knowledge of particle scattering in meteorology and physics was introduced . the particles to be discussed include aerosol particles , fog droplets and raindrops and the em wave band in the discussion is near - infrared . in the second part , the mie theory was briefly reviewed and was applied to investigate the scattering characteristics of spherical atmospheric particles , the result shows that in the visibility measurement meter using forward - scattering method , when the working wavelegth is between 0 . 8 m ~ 2 m , the scattering angle is between 25 ~ 40 , the distinguishability and the relative scattering intensity would be better than those under other conditions . in the third part , the superellipsoid was used to describe a wide range of shapes such as spheres . ellipsoids and cylinders . an improved t - matrix method which can be used to calculate arbitry shaped particle ' s scattering field was introduced , and the scattering characteristics of non - spherical atmospheric particles was investigated with this method 计算结果表明，从相对散射强度、同一方向上不同粒子散射的可区分程度来看，在散射式能见度探测仪器中，工作波长介于0 . 86 m 2 m ，探测角度选取前向25度40度时，探测的结果将会是比较理想的。第三部分中，使用超椭球方程来统一描述各种非球形粒子的形状，然后使用t矩阵方法计算了一些形状的非球形粒子的近红外散射特性。另外，在本文中还针对球形粒子的散射场提供了一种三维可视化方法，使对散射场强度的空间分布的理解更加简单，直观。
The mean and the mean square error of the difference between the scattering field and the cancellation field are calculated . the probability of the cancelled effect under the given errors is also computed in the cases that the azimuth angle varies with the law of uniform and random distribution , respectively 此外，还对被保护目标散射场的对消效应作了统计分析，计算了对消场和散射场误差的均值和均方差，并在方位角以均匀和随机规律变化时给出了它们在给定误差值下存在的概率。
The second part of the work is to analyze the finite array with floquet mode method . the scattering field of two - dimension array is computed and the characteristic of fm is mentioned . at the end of the work , the two methods , fm and mom , are discussed respectively 第二部分工作研究有限阵列电磁散射特性分析的fm方法，总结了fm方法分析阵列散射场的一般步骤，采用fm方法计算了二维有限阵列的散射场，与矩量法做比较，分析了fm方法的优缺点以及数值计算中的一些注意事项。
Based on the theory of geometrical optics , the relationship between the axial force exerted on the micro - sphere particles in the mie scattering field and the main parameters of laser is calculated quantitatively when the absorption is considered . the results not only show the relationship between the axial force and some parameters , that include the absorption coefficient of microscopic particles , the laser wave - length , power and so on , but also are useful for choosing parameters in experiments 摘要以射线光学模型为基础，对微粒直径远大于激光微束的米氏粒子在考虑对光的吸收时轴向力与光源参数的关系进行了计算，计算结果给出了轴向力与微粒的吸收系数、波长、激光功率等参数的关系，为实验中参数的选择提供了依据。
