Аннотация:Electrodynamics of Si-SiO2-TiO2-Pt-PZT heterostructures is studied in the frequency range from 5 to 5000 cm-1 by monochromatic BWO (backward wave oscillator) and infrared Fourier-transform spectroscopy techniques to derive the dielectric characteristics of the sol-gel porous ferroelectric PbZr0.48Ti0.52O3 films. Broad frequency band dielectric response of PZT films with different density is constructed using the oscillator dispersion models. The main contribution to the film permittivity is found to form at frequencies below 100 cm-1 depending strongly and non-linearly on the film medium density.