Effect of transmitter current waveform on TEM response

This paper investigates the effect of different transmitter waveforms on the transient electromagnetic (TEM) system response. For a loop target in free space, the voltage response is derived for waveforms of square, trapezoidal, half-sine and triangular shape. It is found that, for lower conductivity object, every waveform excites almost the same response during on-time and off-time, respectively. Among all waveforms, the maximum response is generated by a square pulse. For low signal to noise ratio (SNR) during off-time, square pulse is usually used for lower conductivity object detection. For higher conductivity object, response sharply decreased with the increase of the conductivity during off-time. While the responses of half-sine and triangular shapes are constant with the increase of conductivity. So we concluded that half-sine and triangular shapes are suitable for on-time detection. By properly increasing the base frequency, high SNR and high space resolution can be obtained.