E-fields of electrode-based through-the-earth (TTE) communication

An electrode-based through-the-earth (TTE), or linear TTE, communication system sends its signal directly through the earth overburden of a mine by driving an AC current into the earth. The resultant current, present at the receiver, is detected as a voltage and communication is established. The electrode-based TTE system may achieve a considerably large transmission range >305 m (1000 ft). This kind of system may be implemented for emergency communication close to an area such as a refuge alternative or other strategic location to establish communication between underground miners and the surface. Since it does not rely on extensive infrastructure underground, this communication would provide an alternate path out of the mine. Given the attenuation characteristics of the earth-which is the major factor determining the performance of TTE systems-the receiver sensitivity, transmitter antenna length and orientation, working frequency, and transmitted current required for communication can be estimated and determined. In an effort to estimate the earth attenuation, the analytic solution for the electrical field distribution of an electrode-based TTE communication system in a homogenous half-space is derived. A prototype system was built and tested at a mine site. The test data is compared with the modeling results, and a close agreement is found between them.