Comments, with reply, on "Electric field sensors in electromagnetic sounding" by Wu Xiao Wu and David V. Thiel

The conclusion by W.X. Wu and D.V. Thiel (see ibid., vol.27, p.24-27, Jan. 1989) that a horizontal, insulated, ungrounded antenna is a dependable probe for the horizontal E fields is questioned. It is shown that the horizontal insulated antenna should be grounded at the end points to provide a reliable measurement of the actual surface impedance in conjunction with the measurement of the horizontal magnetic field. Wu and Thiel´s experimental data supports this contention. In their first reply the original authors offer arguments and counterexamples to further support their case. In further comments J.R. Wait states that he has not altered his views on the matter as expounded in the letter. In a second reply Wu and Thiel elaborate on experimental details omitted in the original work, which it is hoped will clarify the previous explanations they presented.<>