ELECTRIC FIELD MEASUREMENT SYSTEM

摘要

In the application a measurement system for precisely measuring low frequency electric fields is described. The measurement system consists of a capacitive antenna (10), having two parallel, conductive plates (11, 12), the potential between the plates (11, 12) being a measure for the electric field present. The capacitive antenna (10) further comprises a high impedance element (13) which provides the potential between the plates to an electrical-optical converter (14). The electrical-optical converter converts the potential into an optical signal. The optical signal is coupled into an optical fibre (20). This optical fibre (20) transports the optical signal to an optical-electrical converter (30), where the optical signal is converted into an electric signal, which is measured by a known measurement device (31), like a spectrum analyzer. By the use of an optical fibre (20) for transport of the signal to be measured from the capacitive antenna (10) to the measurement device (31), disturbances on the field to be measured are avoided. The plates of the capacitive antenna, preferably, have dimensions of only a few centimetres, thereby keeping the influence of the antenna on the field to be measured as low as possible. The high impedance element (14) makes it possible that weak, low frequency electric fields, having a frequency of only a few Hz, can be measured very accurately.