The probe measures both the field's amplitude and direction. It is designed to measure DC-fields but it can also measure AC-fields. The probe is designed to measure electric fields from 10 V/mm. It can measure much lower fields if the signal is properly filtered. Fields down to 0.1 V/mm have, for example, been measured at 50 Hz. The upper limit is dependent on the risk of a triggered breakdown in the air since the probe raises the field with a factor of 2 to 3 times locally around the casing. Depending on the safety margins, it should not be used
in fields higher than around 500 V/mm. The outer dimensions of the probe casing are 26 mm in length and 12 mm in diameter, see Fig. 1. It is possible to perform measurements with the probe at high electrical potential.