The effects of broadening of frequency spectra of quasi-monochromatic very low frequency (VLF) signals were observed in the polar ionosphere when VLF transmitted signals were registered on the satellite ''Intercosmos-19''. Broadening of the spectrum was mainly registered on the electric antenna to the extent of Δf≤1 kHz. Broadening of the VLF signal and intensive extra low frequency (ELF) noise with f<1 kHz were observed simultaneously. Such effects can be explained by a transformation of the initial whistler-wave, into whistler-mode waves with wave-normals very ner the resonant cone, by small-scale ionospheric irregularities. These irregularities can be caused by ion-acoustic or ion-cyclotron waves. The effect of the broadening of the VLF signal spectrum can be used as a diagnostic of ionospheric turbulence and field-aligned electric currents in the upper ionosphere.