Development and validation of a low‐frequency modeling code for high‐moment transmitter rod antennas

Abstract

The goal of this research is to develop and validate a low‐frequency modeling code for high‐moment transmitter rod antennas to aid in the design of future low‐frequency TX antennas with high magnetic moments. To accomplish this goal, a quasi‐static modeling algorithm was developed to simulate finite‐length, permeable‐core, rod antennas. This quasi‐static analysis is applicable for low frequencies where eddy currents are negligible, and it can handle solid or hollow cores with winding insulation thickness between the antenna's windings and its core. The theory was programmed in Matlab, and the modeling code has the ability to predict the TX antenna's gain, maximum magnetic moment, saturation current, series inductance, and core series loss resistance, provided the user enters the corresponding complex permeability for the desired core magnetic flux density. In order to utilize the linear modeling code to model the effects of nonlinear core materials, it is necessary to use the correct complex permeability for a specific core magnetic flux density. In order to test the modeling code, we demonstrated that it can accurately predict changes in the electrical parameters associated with variations in the rod length and the core thickness for antennas made out of low carbon steel wire. These tests demonstrate that the modeling code was successful in predicting the changes in the rod antenna characteristics under high‐current nonlinear conditions due to changes in the physical dimensions of the rod provided that the flux density in the core was held constant in order to keep the complex permeability from changing.