Measurements have been made of the resistance of three different electric field sensing antennas on the Wind spacecraft in the solar wind. The measurements have been separated into base resistance and plasma resistance by assuming that the plasma resistance is inversely proportional to the antenna length. Simple formulas for the resistances, as functions of the plasma electron flux, are given and fitted to the data. The results imply that the division of the signal by the base resistance is important and needs to be taken into account in low-frequency measurements of electric fields when the antennas are shorter than a few tens of meters. ¿ 2001 American Geophysical Union