Range Ambiguous Clutter Suppression with Azimuth-Elevation 2D Joint FDA-MIMO STAP for Bistatic Space-Based Early Warning Radar

The bistatic space-based early warning radar (SBEWR) represents an innovative detection system, seamlessly integrating the advantages of bistatic detection and SBEWR, garnering increasing attention in the field. However, the extended detection range and the influence of Earth's rotation pose signifi-cant challenges for the bistatic SBEWR in effectively suppressing range ambiguous and non-stationary clutter. This paper intro-duces a novel approach to address these challenges by exploiting the range dependence in both azimuth and elevation spatial frequencies of the bistatic SBEWR. Initially, our method employs multiple-input multiple-output (MIMO) radar with elevation frequency diverse array (FDA) to enhance the discrimination between elevation spatial frequencies associated with different range-ambiguous echoes. Subsequently, an elevation bandpass fil-ter is applied to extract the desired range-ambiguous echoes while concurrently suppressing other range-ambiguous echoes out of band. However, the excessive width of the elevation bandpass filter leads to the persistence of residual echoes. To resolve this, azimuth FDA-MIMO is applied to extend the interval between azimuth spatial frequencies of the residual echoes. Following this, an azimuth bandpass filter is designed to selectively extract echoes associated with the to-be-detected ambiguous range. Finally, traditional space-time adaptive processing is employed to achieve effective clutter suppression. Experimental results validate the effectiveness of the proposed method.