Location determination for subsurface communication device

A method of locating a sensor, comprising:

• placing an environmental sensor within an electromagnetic absorbing material, the environmental sensor being configured to sense at least one environmental condition of the electromagnetic-absorbing material and to output sensor data representing the at least one environmental condition;
• providing a modulator in communication with the environmental sensor, wherein the modulator is configured to encode the sensor data onto a carrier at a predetermined carrier frequency;
• providing a switch-mode amplifier in communication with the signal output and a first multi-turn coil, wherein the switch mode amplifier comprises:
• a first switching device configured to transition between an on state and an off state;
• a load network coupled to the first switching device, the load network including a terminal configured to receive an input voltage and the first multi-turn coil, the inductance and capacitance of the load network being tunable to form a resonant circuit at the predetermined carrier frequency;
• generating, by the first multi-turn coil, a beacon signal, wherein an amplitude of the beacon signal is adjustable;
• receiving, by a second multi-turn coil of a receiver positioned outside of the electromagnetic-absorbing material, the beacon signal;
• measuring the amplitude of the received beacon signal;
• and
• determining a location of the environmental sensor based upon the measured amplitude of the beacon signal.