Electrode impedance measurement in through-theearth communication applications

Through-the-earth (TTE) communications are deployed in hostile environments with the rock as communication channel. The ground electrodes are one of the medium access solutions for this type of communications. Its operation is based on the injection of an electrical current into the earth and the detection of a potential difference between the receiver electrodes. The electrode impedance depends on many factors: the material (rock, earth ) where the communications take place, the wires used to connect the system to the electrodes, the type of electrodes etc. It is very important to know, in detail, this impedance in order to properly design the TTE communication transmitter. In this study, a measurement method developed to characterise the electrode impedance is presented. The method is applied in several terrains including three measurements as an example. Moreover, a circuit equivalent model for this impedance is proposed. The model parameters are adjusted to the measured data with a good fit.