Mutual electromagnetic coupling of coaxial loops in a borehole

The exact integral solution is obtained for the fields of a small circular loop that is coaxially located in a cylindrical borehole in homogeneous rock. The result is employed to calculate the mutual impedance between two coaxial loops within the borehole. It is found that, under most conditions, mutual impedance does not depend on the presence of the borehole, and thus the configuration is well suited for electromagnetic probing of the host rock.