Reader, relay sensor, and buried sensor for magnetic field communication and method for magnetic field communication using relay sensor

A magnetic field communication method using the reader, the relay sensor, embedded sensors, and the relay sensor for a magnetic field communication is disclosed. The technical problem with the relay sensor for achieving a magnetic field communication method comprises the steps in which the output of the reader output signal or reader output power to the embedded sensors embedded in the ground by a reader for a magnetic field communication, the buried sensor is the output of the reader output receiving a first reader signal, or the first reader power based on the signal or reader output power, and in which the embedded sensors receive a second reader signal, or the second reader power from the relay sensor located between the reader and the buried sensor and a step.