The multispectral analysis of the wave field components of an electromagnetic wave observed at a fixed point in a magnetoplasma is performed using a maximum entropy method. The validity of the analysis is a posteriori tested comparing the propagation characteristics of the waves, as derived from the spectral matrix estimates, to the propagation characteristics predicted by the magneto-ionic theory. The techniques so developed are applied to the analysis of ground-based transmitter signals observed on GEOS 1. Comparisons with results obtained from the Welch (1967) method show the superiority of the maximum entropy method of spectral analysis, at least in the case of narrow-band electromagnetic emissions.