Interpretation of scattering phenomenology in dielectric-coated wire via joint time-frequency processing

We carry out a phenomenological study of scattering from dielectric-coated wires. The scattering data are collected by both numerical simulation and by chamber measurement. The short-time Fourier transform (STFT) technique is used to extract the pertinent scattering physics of the structure. The surface wave, or the so-called the Goubau mode, is excited due to the dielectric coating around the wire. The features of this mode are studied and an interpretation of the dispersive behavior is given in the joint time-frequency plane with the help of the STFT technique. One way to gain better resolution in the joint time-frequency plane is with the Wigner-Ville distribution (WVD). However, it is well known that cross-term interference occurs between any pair of auto-terms in the joint-time frequency plane. To suppress the cross terms in the WVD, the time-frequency distribution series (TFDS) which takes the WVD of the Gabor expansion of the original signal is implemented. By keeping only the lower order terms in the series, a good compromise between resolution and cross term interference can be achieved.