Reflections occur at interfaces between different materials. Thus if the relative dielectric constant is known, the depth of the reflective interface may be found from the measured return signal time. A sequence of trigger pulses is generated in the control unit by the radar circuitry. The trigger pulses are sent through the control cable to the antenna. In the antenna, each trigger pulse is transformed into a bipolar transmit pulse.
Energy is transmitted in a conical pattern into the subsurface.
The transmitted pulses encounter different materials in the subsurface with different dielectric properties. In the interface, some energy is reflected back to the subsurface and detected by the antenna. The reflected signals are sent to the control unit. In the control unit, The signals are processed and displayed. Two material properties that affect the GPR use are conductivity and relative dielectric permittivity.