Context and objectives
To study the effect of electromagnetic radiation in the microwave reach (2-16 GHz) on bare terrain, in particular with regard to soil moisture.
Expected scientific results
This study attempts to explain the observed oscillations in the backscattering function of a bare soil with given moisture content and given roughness characteristics. It is hypothesised that these oscillations are the result of amplitude modulation due to surface and volume scattering. If this is true the dominant periods of these oscillations should be observation frequency dependent. Moreover, these dominant periods can be related to the observation depth of the microwave signal. Therefore we have used the Hilbert transformation to analyse the signal, since this technique yields information about the local properties of a non-steady state signal. For the data set under study, we have found that the depth of observation for volume scattering decreases rapidly with observation frequency.