Time-frequency analysis of electromagnetic pulse responses from a one-dimensional plasma medium

Electromagnetic (EM) pulse responses from one-dimensional plasma layer are analyzed in time-frequency domain by using the short-time Fourier transform and the scattering mechanisms of EM wave in plasma media are investigated. Through the processing of numerical scattering data for a multi-layered plasma medium, several distinct scattering mechanisms related to the dispersion can be observed in time-frequency plane. Clear interpretations are given for these scattering mechanisms: dispersion curves due to the multiple reflections inside the plasma layer, the effect of resonance in each layer, and the reflection from a turning point where the frequency of the incident pulse coincide with the plasma frequency. Although these scattering mechanisms are not immediately apparent in either the time domain or frequency domain, they can clearly be identified in time-frequency domain.