Exploiting the full information of the coupling ratio measurements in frequency domain electromagnetic induction instruments

Frequency domain electromagnetic induction (FDEM) sensors are used regularly to investigate near-surface electrical properties for diverse purposes.  FDEM instruments measure the coupling ratio between the secondary magnetic field induced in the ground and the primary magnetic field of the direct wave propagating from a transmitter through the air to the receiver coil, which is a complex ratio, where the real part is called in-phase part and the real part is called the out-of-phase or quadrature part. Usually, the quadrature  part of the data measurements is used to estimate the electrical conductivity of the shallow subsurface. In this study we show the outcome of the estimation of an electrical conductivity model using both quadrature and in-phase  parts of the coupling ratio. We simulate the full solution measurements (quadrature and in-phase) and used only the quadrature part as data to estimate 1D electrical conductivity models of the subsurface in a lookup table. Then, we compare this estimation with the resulting one using the full solution as data measurement. Our results provide insight on the information that the in-phase part provides about the distribution of electrical conductivity with depth.