Determining Media Absorption Loss Using Embedded Harmonic Transponders

In this work, we present a means to measure the forward channel loss of a bidirectional communication link using harmonic transponders. The transponder is embedded in an unknown environment at one side of the link and data are collected only at the other. The approach leverages an amplitude modulated interrogation signal and the device's nonlinearity, to accurately ascertain the power incident at the harmonic transponder. The approach is applied to determine the absorption loss in soils having different moisture contents.