Noise of magnetic core

A transformer made for impedance matching of detector and preamplifier is considered like a dissipative two-port network. The noise voltage, induced by ferrite core of transformer on the receiver end, is derived from first principles. An inductance of transformer windings is considered to be finite and no additional shunt magnetizing inductance is introduced. This automatically eliminates the problem of divergence of integral of spectral density of noise related to losses in the magnetic core, as discussed in literature.