Broadband Low-Frequency Electromagnetic Induction Sensor

A broadband electromagnetic induction (EMI) sensor is developed to detect and discriminate between types of metallic targets. The sensor uses a single dipole transmit coil and two dipole receive coils in a differential configuration. The sensor operates in the frequency domain and collects data at eight logarithmically spaced frequencies from 105 Hz to 1.905 kHz. The system is configured for relatively distant targets in fairly conductive soil or water. The system is designed to be relatively lightweight while being sensitive and making accurate measurements. Experimental results are presented for a prototype sensor.