This technology is an economical system for detecting and characterizing signal loss in communications channels with power at only one end of the channel. It is used to measure the properties of the medium itself, such as the amount of moisture.
One or more passive sensors can be embedded in situ during construction (at a point or in an array) in a substrate (such as the cement around bridge supports or rail bed foundation ballast) that acts as the channel medium. This system can be used to detect excess moisture levels that may hasten deterioration and structural failure in infrastructure such as bridges, railroad beds, etc. The system may also be used to monitor recovery of burnt landscapes or moisture levels in agriculture by embedding sensors in the soil. The embedded sensors can be interrogated as needed by a transmitter, receiver and signal processor located in a drone, railroad car, tractor, etc.