A radar screening system that detects an object in a region of interest by transmitting coded signals having a first polarization and receiving coded return signals having at least a second polarization. Suitably the transmitted signals have one polarization and some return signals have the same polarization and other return signals have an orthogonal polarization. The return signals are processed into voxels to calculate at least a cross-polar value at each voxel. Voxels are identified as being from an object of interest if an indicator using at least the cross-polar value exceeds a threshold. Preferably the indicator uses at least a ratio of the cross-polar value and the co-polar value. The radar screening system may also perform automatic target recognition by taking into account shape and location of the object of interest.