Two novel methods

which are referred to as signal subspace comparison method(SSCM)and antenna pattern method(APM)

are proposed to estimate the channel phase errors for spaceborne high resolution and wide swath(HRWS)synthetic aperture radar(SAR)system.The SSCM is based on the fact that the space spanned by the signal eigenvectors referred to as the signal subspace is equal to that by the practical steering vectors.One of the great advantages of this method is its low computational burden and high accuracy.Combined with the antenna patterns

the APM estimates the channel phase errors directly without decomposing the covariance matrix

which is suitable for uniform distributed scenes.Finally

the ground-based real data confirms the validity of the two approaches.