A magnetic field sensor with omni-directional sensitivity
W.A. Pasmooij · 1994
An active magnetic field probe with omni-directional sensitivity has been realized by means of two small active loop antennas and a '90 degrees -hybrid'. The response is flat within 3 dB in the frequency-range from 100 kHz to 8 MHz. The noise floor of the instrument (expressed in an equivalent H-field) is -10 ( mu A/m) at 1 MHz and 5 dB( mu A/m) at the 3 dB cut-off frequencies 100 kHz and 8 MHz. This is sufficient to measure the H-fields at short distance from telecommunication-wiring as the limits for CM-currents are set by CISPR G at 20 dB( mu A).