The purpose of this paper is to develop a modeling tool for VLF/LF antennas taking into account surrounding components such as insulators. Numerical results of the field distribution along an insulator using the transmission line method (TLM) are pesented. These results are compared with commercial software data and show a good agreement. A capacitive electric model deduced from the voltage and current behavior is calculated for the insulator. This model could be integrated as lumped component in a global TLM code to model typical VLF/LF antennas taking into account surrounding insulators.