Active magnetic field sensor for measurements of transients

An active magnetic field sensor consisting of an electrically small loop, two ferrite core transformers, and a balanced amplifier with a low input impedance is suitable for measurements of fields, in a broad range of frequencies, and transients. The sensor provides a flat transfer function from approximately 600 Hz to 200 MHz (3 dB roll-off frequencies) and high-fidelity reproduction of pulses with a risetime of 2 ns. The sensor can be used to measure fields from less than 0.2 mA/m to approximately 0.2 A/m. The sensor has a minimal response to the electric field (at least -20 dB). The sensor´s dimensions are 6 cm×6 cm, and the electronic circuitry is contained in a box of approximately 5 cm×8 cm×3 cm