The calculation of target poles with wavelet transform for electromagnetic target discrimination

In this paper, a method oriented to the extraction of target poles is presented for target recognition purpose. By applying wavelet transform to whole signal, the mention method obtains target poles with a map extracted in time and frequency axes simultaneously. For this purpose, with complex Morlet wavelet transform, a map having sufficient resolutions in both axes is obtained by multiplying two maps, one using narrowband and another using wideband mother wavelet. The peaks in the frequency axis of the resulting map give the oscillation coefficients of the poles, and the attenuations in time axis give the damping coefficients of the poles. In this study, the method is initially applied for a dielectric sphere whose pole values can be analytically calculated and it is observed that the calculated pole results are highly consistent with theoretical values especially with respect to oscillation coefficients. Afterwards, for target discrimination purpose, the method is applied to two small-scale airplane targets whose pole values are theoretically unknown and it is shown that although the dimensions of airplanes are very close, their pole values are considerably different.