Abstract—An experimental stand has been created to assess the characteristics of the electromagnetic field under which the current–voltage (I–V) characteristic of semiconductor elements change. The developed stand was used for a series of experiments on the effect of signals with different parameters on a KD520A diode in order to record changes in the slope of the diode's I–V characteristic as an onset degradation feature of the p–n-junction. This is done by recording the amplitudes of higher harmonics under the action of microwave signals.