An atmospheric electrical voltmeter follower

Horizontal passive antennas used to sense the potential of the atmosphere above the earth's surface demand high performance from attached electrometer voltmeter circuits. The floating follower circuit described here allows precision de measurements of potential difference in the range +/-10 V, while maintaining input currents of order 10(-15) A. Voltage offsets over most of the dynamic range are less than 50 mu V, allowing precise guarding of the input electrode to further minimize input leakage currents. The battery-operated system is well suited to atmospheric electrical measurements using horizontal antennas operating within 10 cm of the earth's surface, and provides an inexpensive means of precision high impedance voltage measurements. (C) 1996 American Institute of Physics.