Polarimetric Interferometry – Target Detection Applications

In this section we consider the problem of radar detection of stationary targets obscured by foliage clutter. This is a classical detection problem for which the usual solution approach is to reduce the radar centre frequency as far as possible, so minimising scattering by the foliage while hopefully maintaining a significant target response. These approaches are based on backscatter intensity as the prime radar observable. In this paper we consider a new approach. Here we employ the phase of a radar interferometer as the prime observable and attempt the detection of targets by using the variation of phase with polarisation to reduce the foliage returns and maintain the target response. In section 2 we provide an introduction to polarimetric radar interferometry and consider the nature of the phase signal obtained in volume scattering. In section 3 we then extend this argument to consider the influence of a target on the observed phase and show how we can use this to develop a filter for enhanced target detection. In section 4 we describe a processing algorithm based on this analysis of volume scattering and in section 5 summarise the main components of a vector wave propagation and scattering model used to simulate coherent radar returns from targets embedded in foliage. In section 6 we present results from a simulation based on this model of corner reflectors embedded in a pine forest and demonstrate the ability of this technique to provide enhanced detection by showing raw and filtered signal channels for a cluster of hidden trihedral reflectors.