Indoor Polarimetric Radar Measurements On Vegetation Samples At L, S, c aNd x band

Abstract

An entropy based decomposition technique is applied to some wide-band polarimetric data sets acquired under fully controlled conditions. The measured targets include various tree types and maize plants. The acquired data are analyzed firstly by displaying the loci of the Entropy-Alpha pairs both as a function of the working frequency and the incidence angle. This analysis shows which are the dominant scattering mechanisms of the target as a whole. The decomposition scheme can equally be applied in the time domain. The decomposition results in the time domain show the elements of the sample originating the scattering mechanisms observed in the frequency domain, thus providing useful physical characteristics for constructing equivalent electromagnetic models for further analysis and inversion algorithms. Results show that young and mature maize samples evidence a different relation between the extinction coefficients at different polarizations. Penetration into the samples of maize is high for all frequencies, even at X band. The mature samples can be modeled as a two-layer volume over the ground, whereas the young sample is better represented by one-layer over the ground. On the other hand, the time domain results from a group of young fir trees show the varying penetration depth as a function of frequency, and plots of entropy and average alpha as a function of range also confirm that this target can be modeled as a random volume over the ground.