In situ measurements of the complex propagation constant in rocks for frequencies from 1 MHz to 10 MHz

The complex propagation constant for frequencies between 1 MHz and 10 MHz has been measured for propagation between bore holes in granite rock at a site near Raymond, Colo., USA. The measurement technique consisted in Comparisons of the phase and amplitude of signals received on two identical dipole antennas spaced at different distances on a radial from an isolated transmitter. The conductivity and permittivity of the medium calculated from the propagation constant are compared with laboratory measurements of samples from the same boreholes, and reasonably good agreement is obtained.