An adaptive clutter rejection scheme for atmospheric radars

Clutter rejection is among the most important issues in radar signal processing, for which adaptive antenna technique is a powerful means. Compared to other applications of the adaptive antenna, however, atmospheric radars require strict conditions; The main antenna beam pattern should not be altered since the target region is defined by its shape. Especially, the loss of the antenna gain should be kept to no more than about 0.5 dB in order to maintain the high sensitivity of the system. Also, clutter from surrounding mountains is often stronger than the desired weak scattering from atmospheric turbulence. We propose a new algorithm which satisfies the above conditions, and confirm its capability by applying to actual radar data. Despite the fact that no information is given on the spectral features of the desired and undesired signals, only the clutter echoes from surrounding mountains were effectively cancelled without affecting the desired echoes from atmospheric turbulence.