A method of THz spectral dynamics analysis (SDA) of medium response in the THz and GHz ranges, which was developed
by us in previous papers for detection and identification of materials, is used for the treatment of experimentally
measured signals, passed through selected explosives, including those hidden under covering materials. This technique is
based on the window sliding method and on restoration of the THz pulse. It allows researchers to follow the dynamics of
many spectral lines in one set of measurements simultaneously and to obtain the full information about the spectrum dynamics
of the THz pulse. Relaxation time of rotational transitions, for example, can be determined too. This information
gives an opportunity to detect and identify materials despite the similarity in their THz spectra-which may be identical.
We show that the spectrum dynamics of THz pulses, passed through the explosives hidden under plastic, cotton and
leather barriers-covers, differ widely for these media despite little difference in their spectra. Consequently, our method
allows for detection and identification of the hidden explosives with high probability.