A data-adaptive time-frequency representation applied to the scattering from a jet aircraft

The electromagnetic (EM) scattering from the engine inlets and exhausts of a jet aircraft are a significant part of the total RCS from the aircraft. The engine inlet/outlets can be modeled as open-ended waveguide cavities with complex termination due to the engine turbine. It is known that, for certain frequency band, the scattering from such cavities is dispersive. Time-frequency representations (TFR) have been recognized as the appropriate tool for describing the scattering from frequency-dispersive structures. A TFR based on a multi-resolution tiling of the time-frequency plane is presented. The idea of a multi-resolution representation is often associated with the wavelet transform (WT). The multi-resolution property of the WT is extended to obtain a data-adaptive multi-resolution/multi-focusing TFR. This TFR is then applied to the backscattered signal from the engine outlets of an aircraft in flight.<>