Nonstationary Clutter Suppression Based on Four Dimensional Clutter Spectrum for Airborne Radar With Conformal Array

Conformal array antenna is one of the important development directions of airborne radar in the future. Its advantages include aerodynamic design, larger effective aperture and minimal payload weight etc. However, conformal array antenna usually has non-linearity feature. The special geometry deteriorates the performance of the antenna pattern and causes nonstationary clutter distribution. The performance of conventional space time adaptive processing (STAP) methods is degraded. Aiming at the clutter suppression problem of the conformal array airborne radar under the situation of range ambiguity, a four-dimensional space-time clutter spectrum adaptive compensation method has been proposed. Based on the establishment of a conformal array airborne radar clutter signal model and clutter distribution characteristics, this method transforms the conformal array into a virtual uniform linear array, and estimates the four-dimensional minimum variance distortionless response (MVDR) spectra by means of space-time smoothing processing. Then it compensates the data in the short-range nonstationary clutter region, and estimates the clutter and noise covariance matrix based on the compensated data to perform space time adaptive processing. This method does not move the target signal while realizing the short-range nonstationary clutter compensation. At the same time, by compensating the data of all the short-range regions, it overcomes the influence of prior system parameter error and array error on the compensation methods, which has strong robustness feature. The simulation results verify the effectiveness of the proposed method.