CAJ | 학술논문

提出用于二维半空间时域有限差分的瞬态场外推计算方法。该方法把上半空间远区场分作3部分：第1部分是上半空间外推边界上电磁流辐射场沿直达波路径的贡献；第2部分是该电磁流辐射场沿反射波路径的贡献；第3部分是下半空间外推边界上电磁流辐射场沿透射波路径的贡献。关于后两部分的计算要点是：用斯奈尔定律确定外推边界上电磁流辐射场的反射点和透射点，并把它们投影至沿观察点方向的时间盒子中；计算电磁波从等效源至反射点或透射点所需的时间，以此确定真正的投影时间盒子；用相应极化波的反射或透射系数作为沿反射或透射路径对远场贡献的比例系数；最后用两个模型验证二维半空间瞬态场外推算法。计算结果与已报道成果具有很好的一致性。
제출용우이유반공간시역유한차분적순태장외추계산방법。해방법파상반공간원구장분작3부분：제1부분시상반공간외추변계상전자류복사장연직체파로경적공헌；제2부분시해전자류복사장연반사파로경적공헌；제3부분시하반공간외추변계상전자류복사장연투사파로경적공헌。관우후량부분적계산요점시：용사내이정률학정외추변계상전자류복사장적반사점화투사점，병파타문투영지연관찰점방향적시간합자중；계산전자파종등효원지반사점혹투사점소수적시간，이차학정진정적투영시간합자；용상응겁화파적반사혹투사계수작위연반사혹투사로경대원장공헌적비례계수；최후용량개모형험증이유반공간순태장외추산법。계산결과여이보도성과구유흔호적일치성。
An algorithm for extrapolating the transient field in two-dimensional half-space for the finite-difference time-domain(FDTD) method is firstly presented.In this algorithm,the far-zone scattered field consists of three parts.The first two parts of the field are generated by the equivalent electromagnetic currents at the extrapolation bound in upper space,propagating along the paths of directed and reflected waves,respectively.And the third part is resulted by that currents at that bound in lower space,its propagation following the path of the transmitted wave.To caculate the latter two parts,the reflection and transmission points should be determined with the knowledge of Snell’s law and then projected on to the observation time bins,moreover the proper time of the wave propagating from the equivalent source to those points should also be worked out and used to delay those bins,with the reflection or transmission coefficients used as the contribution factor to the far field.Then the proposed algorithm is validated by the applying far-zone scattered fields to two examples.