Absolute Calibration of Antennas at Extremely Low Frequencies

The object of the work was the calibration of ELF (extremely low frequency) electric field sensors. In particular it was desired to compare the calculated with the measured effective height or, equivalently, to compare the measured terminal voltage at a receiving antenna with the predicted value when the incident field is precisely known. This incident field was generated by an electrically very short, thin linear radiator. Formulas are given for the field in the immediate vicinity of such a radiator above a perfectly conducting ground. Also given is an expression for the integral of this field along a vertical path starting at ground level. (Author)