Characterization and analysis of electric-field sensors

With a growing number of electric-field sensors becoming commercially available, there is an increasing need for high-quality test and evaluation processes. The electric-field sensing team at US Army Research Laboratory (ARL) possesses a low-frequency electric field “cage,” which provides a ~1-m3 volume with electric-field accuracy >99%. A state-of-the-art LABVIEW code has been developed to control laboratory equipment capable of generating uniform electric fields at frequencies of less than 20 kHz and magnitudes of less than 5 V/m. This paper characterizes the performance of three small electric-field sensors of two different types. Pairs of Plessey EPIC and QUASAR RVS electric potential sensors are tested in a fixture with a 60-mm separation distance. An integrated ARL “D-dot” sensor with an electrode area of ~15 mm by ~24 mm is also tested; this sensor responds to the time-derivative of the sensed electric field. These sensors are characterized in terms of frequency response, noise power spectral density, dynamic range, linearity, and total harmonic distortion. Characterization tests are performed over frequencies between 10 Hz and 10k Hz, and magnitudes between 4 mV/m and 4 V/m. We determined the RVS sensors give the flattest frequency response throughout our entire testing bandwidth, while the EPIC sensors have the lowest harmonic distortion at 0.65%.