Rejection of propeller generated multipath interference using transform-domain array processing

Several array processing architectures have been devised for mitigation of multipath interference. Those algorithms have focused on the rejection of terrain scattered interference, sidelobe and mainlobe clutter, and hot clutter. This paper focuses on evaluating and rejecting multipath interference due to propellers or rotor of the radar receiver aircraft or helicopter. This type of interference is characterized by an induced Doppler spread proportional to the angular velocity of the propeller or the rotor. Furthermore the reflected signal represents the near-field component of the propeller scattering signatures. Spatial averaging followed by a transform-domain adaptive beamformer based on the Frost (1972) algorithm is used to reject this type of propeller generated multipath interference.