DUALITY OF THE ELECTRIC COVERING FIELDMILL AND THE FLUXGATE MAGNETOMETER

This work treats two de field sensors. The first sensor is the ''cover ing fieldmill'' that is employed to measure de electric fields, The se cond sensor is the ''fluxgate magnetometer'' that is utilized to measu re de magnetic fields. An unusual approach is suggested to deal with t he de,ices' evaluation. It is shown that both devices can be associate d with related ac field sensors-electric and magnetic. This associatio n leads to modeling the de sensors by Thevenin circuit models. It is t hen shown that in both cases the coupling between the sensors output c ircuitry and the measured field sources is due to series time-varied r eactances, This enables a similar analytical treatment to both devices , Furthermore, it is also suggested that both sensors are related to t he large family of antennas. As a result, an unusual way is found to r elate the sensors' output signal to the measured field. It is well kno wn that the signal in electric antennas is related to the measured fie ld times the effective antenna length, It is therefore relatively easi ly acceptable that also in the de electric sensor case a similar relat ionship holds, The work, however, suggests that this relationship (tha t now relates the output signal to the measured de magnetic field time s the effective magnetic structure length) also holds in the fluxgate magnetometer case. An extension of this result is useful when attempti ng to measure nonuniform de magnetic fields and is treated toward the end of the paper,