The Extended Thin-Wire Model of Lossy Round Wire Structures for FDTD Simulations

This paper presents an extended thin-wire model for simulating lightning surge or wave propagation on lossy round wire structures. The wire structures are represented with time-domain cascade circuits, and are integrated into a traditional finite-difference time-domain (FDTD) thin-wire model for the simulation. The model for solid round conductors, cylindrical tubes, and coaxial conductors is provided, and the skin effect is fully considered. In the coaxial structure, the currents in both inner and outer conductors are not necessarily balanced. The proposed model has been validated analytically and numerically, and good agreements have been observed. It has been applied to analyze lightning current sharing in a lossy radio-frequency coaxial cable. Compared with the traditional FDTD method, this extended thin-wire model requires less memory space and computation time in the simulation.