In this paper, we inspect the range and azimuthal defocusing of a buried point scatterer for a low frequency (P and L band) SAR. Firstly, we present the hydraulic electromagnetic and propagation models that allow us to calculate the water content profile in the soil, to deduce the dielectric constant and to simulate the EM wave propagation and attenuation. Secondly, results of pulse simulation and focusing for several configurations (band polarization, incident angle, point scatterer depth, water content profile)are presented and discussed. The advantag es and drawbacks of L and P radars are discussed in the conclusion.