Improving Medium Access in Through-The-Earth VLF-LF Communications

Abstract

In order to improve the communication range of Through-The-Earth (TTE) radio using electrodes, the impedance load seen by power stage load must be minimized. This impedance depends on the wires, the electrode contact and the path between the electrodes (earth). Of the three elements, we cannot influence the earth impedance. The wire impedance can be minimized employing short cables and avoiding coiling them. This paper presents a method for characterizing the electrode contact impedance and provides suggestions to minimize it. Therefore some impedance measurements with several electrodes and a variety of contact conditions have been performed in order to improve our knowledge of medium access. To further prove the results measurements have been made with a voice radio application.