Efficient drive signals for broadband CW electromagnetic induction sensors

Broadband, continuous-wave, electromagnetic induction sensors have been shown to perform well, but they usually use more power than a pulsed induction sensor because of the power wasted in the linear amplifier used to drive the coils. Generally, much more power is dissipated in the power amplifier than in the coils in these systems. Methods for reducing this power are investigated using both linear and switched-mode amplifiers. Significant reductions in the power dissipated by the linear amplifier are achieved by optimizing the signal used to drive the coil. Much greater reductions are achieved with a switched-mode amplifier using an optimized signal that has most of its energy in the desired frequencies for the sensor. Both of these techniques are shown to perform well in a prototype system.