I've been doing some test on a rogowski coil that I built. It is like an air-cored current transformer. I am using it to measure high frequency pulses. The picture shows a discharging capacitor being captured by a current probe (above) and by the rogowski coil (below). I don't know what is causing the inverted voltage peak. Would someone be able to explain this? The picture below is the equivalent circuit of the rogowski coil. Vcoil is the voltage induced in the secondary winding and Vout is the actual voltage measured in its terminals.