Noise influence in time-to-frequency transformation of radiated emissions data

In this paper, the statistical properties of the amplitude of an electromagnetic field measured in the time domain by a three-axial system and processed through the discrete Fourier transform are investigated. Propagation of noise introduced by the three measuring channels is studied under the general assumption of channels with different noise levels. Analytical expressions for the probability density function, the mean value, and the standard deviation of the resulting amplitude are derived in explicit form.