The PEC/PMC Boundary Extrapolation Truncation Method Based On Dyadic Green Functions

Source-Field problem is very important in electromagnetic fields. The expression and computation of Source-Field relation are key steps for electromagnetic problems in both theory study and practical application. Most electromagnetic problems can be settled easily once Source-Field problem was solved. Here we focus on a Source-Field computation method, namely the PEC/PMC Boundary Extrapolation Truncation (BET) method based on Dyadic Green Functions (DGF).As study of Source-Field computation method, the thesis discussed the outer field (radiation field) with source given. The PEC/PMC BET, as a method and idea, shouldn't be limited in outer field, it still works in other aspects, for example, in the computation of the effective source in MoM; and although the discussion in this thesis is based on DGF analytical solution, the PEC/PMC BET method itself doesn't have this ristriction, it can be used in numerical method in principle.The PEC/PMC BET method based on DGF is a kind of half numerical method based on analytical solution. The key step is the Inner-Outer transform to obtain the half-numerical solution of outer problem from the inner analytical solution and take the advantages of both. Not only the complex derivation and computation of analytical solution could be avoided, but also the numerical computational work was decreased obviously. In addition, the boundary treatment was greatly simplified by the average idea of PEC/PMC boundary.The thesis begins with the transmission line model, analyzed the way and processes of solution expansion from inner model to outer model. The similar characteristics of transmission line and uniform wave were compared by their dual relations, and concepts of solution expansion, boundary truncation and Inner-Outer transform were introduced there. The square wave-guide was taken as the inner model of the free space to explain the principle of PEC/PMC BET and Inner-Outer transform.Based on the previous discussion and via the PEC/PMC BET method, the field distribution of the PEC half sheet (outer problem) was discussed through its inner problem model, and it shows the advantages of this method through the theory analysis and numerical computation. In the discussion of half sheet problem, form the construction of inner model to the computation of radiation field, the thesis analyzed and summarized the application steps the PEC/PMC BET method based on DGF.As an another application of PEC/PMC BET method based on DGF, the outer field distribution of a coaxial cable under given point source was discussed following the summarized analyzing method and application steps. Where the application of PEC/PMC BET method was more fully analyzed and summarized, and again the feasibility of this method was proved.Finally, using the method and conclusions of the previous chapters and regarding practical application, the thesis discussed some problems may occur in the design and construction of the mobile communication systems, and some principle solutions were given.