Abstract: We study the detection of weak signal using narrowband dual polarization radar. Description of Instantaneous Stokes sub Vector Sequences (ISVS) of radar target signal and noise are presented. The statistics of ISVS and probability density functions of different signals are given, and a novel detection algorithm proposed through polarization and power accumulation in time. We also derive an analytical expression of false alarm probability and show that the constant false alarm rate (CFAR) of the new receiver can be made bounded. Simulation results show that the radar detection performance is improved. It is useful in applications such as anti radar stealthy, early warning and space detection.

Key words: weak signal, detection, instantaneous polarization