Research On Electromagnetic Modeling Method Based On Face Center Cube (FCC) Grid

In 1966,Yee first proposed the concept of the finite-difference time-domain(FDTD)method internationally.Since Yee proposed this concept in 1996.The finite-difference time-domain method is developing very fast,and many articles about the FDTD method are published every year,and it has been widely used in many scientific research fields and engineering issues.The advantage of this method is that its expression is simple and clear,easy to understand,and it can also describe the electromagnetic characteristics in the time domain more intuitively.The FDTD method itself is also constantly being improved and developed.The continuous advancement and development of computer technology has also brought great convenience to the FDTD method.However,the FDTD method has its limitations.Due to the characteristics of the Yee cell grid,anisotropy problems will occur in the FDTD method,and its accuracy will also be reduced due to this problem.Here,a new computing grid different from Yee's cells is studied.The full name of this new mesh is the Face Center Cube Mesh(FCC mesh).Compared with Yee cell,FDTD method of FCC grid has good isotropic effect and stability conditions.In addition,the calculation accuracy has been improved accordingly.The thesis studies the absorption boundary conditions and near-far field extrapolation boundary conditions of the FCC grid's FDTD(FCC-FDTD)method.And verified by a numerical example.First,we introduce the face centered cube(FCC)grid through the introduction of research background.The spatial distribution of the electromagnetic field of the FCC grid is briefly introduced,and the basic electromagnetic field iteration of the FCC-FDTD method is given.Secondly,the Uniaxially Anisotropic Media Perfectly Matched Layer(UPML)absorption boundary of FDTD method based on FCC grid is studied.Based on the basic theory of UPML,the medium parameter distribution of each edge area and corner top area in two-dimensional and three-dimensional situations is analyzed.Then based on the theory,the iterative formula of the electric field and magnetic field of the UPML absorption boundary based on the FCC-FDTD method is derived in detail.In order to verify the correctness of the algorithm,this paper gives three examples to verify the algorithm.They are: an example with only UPML absorption boundary,an example with connected boundary plus absorption boundary,and an example of relative error compared with the UPFD absorption boundary of traditional FDTD method.The simulation results in all three cases verify the correctness of this method.Finally,the extrapolated boundary conditions of the near and far fields based on the FCC grid-based FDTD method are studied.Based on the Huygens principle,the boundary conditions of the near-field extrapolated far-field fields of the 3D transient field are derived.Then,the single-station RCS of the metal ball is calculated by simulation research to verify the correctness of the near-far field boundary conditions based on FCC-FDTD.