Numerical modelling of transient radiated interferences in time domain by the hybrid ARB method

The novel method of Adapted Radiating Boundaries (ARB) is presented for numerical time domain modelling of transient electromagnetic interference between objects separated by the free space. These objects may be of complex shape and of compound structure containing various conducting, dielectric and lossy materials. In the ARB-method, only those spatial regions are discretized, which are occupied by objects. For the numerical modelling of the field inside these object regions, the TLM-method is applied. The treatment of the electromagnetic coupling of the objects across the free space is based on the equivalence theorem in the Huygens-Schelkunoff representation. By this way the self-coupling of the objects as well as the mutual coupling is treated. The equivalence theorem is taken into account also to obtain adapted boundaries of the discretized regions by using discrete TLM-Green's functions, well adapted to the TLM scheme. The ARB-method is a marching-on-in-time method, yielding a fast and stable algorithm. As an example we model the interference of a transient current on a conductor inside a wall with printed circuit boards inside a shielding enclosure. The numerical results of the ARB method are compared with results of the pure TLM method. While the results show a very good agreement, the CPU time required for the ARB method is one order of magnitude less than the CPU-time required for the pure TLM method.