Stabilization of Thin-Wire FDTD Approach for Resistively Loaded Cylindrical Tube Antennas

Recently, a thin-wire (TW) approach was extended for the finite-difference time-domain (FDTD) analysis of resistively loaded cylindrical tube antennas. This approach was corrected by employing a quasi-static approximation of near-field behaviors and a voltage-current relation over the resistively loaded section without additional grid refinements for fine geometrical features. However, TW correction errors may have large effects on numerical stability of the TW FDTD computation. In this letter, a stabilized correction technique over the resistively loaded section is proposed here. Conduction and displacement currents inside and outside of the resistive antenna can be represented as axial equivalent resistance and capacitance, respectively. Thus, the equivalent resistance and capacitance are incorporated to the voltage-current update equation over the resistive section. Through the TW FDTD analysis of resistively loaded cylindrical tube monopole antennas, we have shown that this modification provides the stable results irrespective of the choice of the resistive loading profile and a time increment under conventional stability condition of the standard FDTD.