Adaptive chaff suppression by polarimetry with planar phased arrays at off-broadside

Clutter with polarimetric signatures different from expected targets can be suppressed by reception orthogonal to the clutter echo polarization. It is shown that this capability is essentially reduced with targets outside the antenna normal direction. This is demonstrated by an example of chaff surrounding a strongly structured and fluctuating target observed with a uniformly transmitting and receiving planar array. Different combinations of adaptive suppression of chaff with the compensation of these directional influences based on the polarimetric antenna matrices are proposed and the corresponding improvement factors are evaluated. It is shown how this can be implemented within the signal processing after reception and partly before transmission. Advantages and drawbacks are discussed