On the Application of Short-Time Matrix Pencil Method for Wideband Scattering From Resonant Structures

A time-frequency technique called short-time matrix pencil method (STMPM) is efficiently employed to analyze wideband scattering from resonant structures. After investigating various parameters of the technique such as time-window length and filtering parameter, some scenarios are studied. First, the proposed technique is applied to the backscattered response from two dipoles spaced 20 cm from each other. The dominantly excited resonances and scattering centers are successfully derived from the time-frequency diagram. Finally, the proposed technique is applied to the time-domain backscattered response from an open-ended circular cavity. Different scattering mechanisms such as resonant, scattering center, and dispersion are studied in the time-frequency diagram of the response. The results are compared with those of the short-time Fourier transform (STFT) and reassigned joint time-frequency (RJTF) techniques. Good resolution in time and frequency domains and its capability of finding low-energy excited poles of the scatterer are the major features of the proposed technique. By utilizing the proposed technique, the damping factor or equivalently the quality factor of the resonances are straightforwardly obtained, which can be useful in the study of resonant-based scatterers.