On measuring electromagnetic surface impedance-discussions with Professor James R. Wait

Electromagnetic (EM) surface impedance, defined as the ratio of the horizontal electric field to the horizontal magnetic field perpendicular to the plane of incidence, has been used in geophysics since the early 1950s for subsurface earth mapping. Traditionally, the electric field component has been measured using a staked voltage probe. In 1989, Wu and Thiel suggested that an insulated wire dipole without the stakes was a more reliable measurement technique. Wait (1989) responded to this paper and the discussion continued until Wait's last comments were published in 1999. In this paper, the final arguments are summarized. The major conclusion reached is that either technique can be used provided caution is exercised, particularly at higher frequencies.