Evolutions of Partial and Global Resonances in Transient Electromagnetic Scattering

Time-frequency (TF) analysis of a transient electromagnetic signature from a radar target is conducted. Using an example of a bent wire target, it is demonstrated that the evolution of "partial resonances" in the early time period and the "turn-on time" of the global resonances in the late time period can be clearly observed in the TF domain. This demonstrates that the hybrid wavefront singularity expansion method (HWSEM) model better describes the scattering physics than the original singularity expansion method (SEM). Furthermore, occurrence of various scattering mechanisms and their interactions are clearly revealed and thus TF analysis can be considered as an important alternative means of studying transient scattering, especially for complex targets from which analytical solutions are usually not available.