Taught herein is a passive channel calibration method wherein a non-linear antenna array sets an antenna array to a non-linear formation that contains at least a combination of translation invariant dual array-element couples, detects single-azimuth ocean echoes via combinations of translation invariant dual array-element couples, estimates channel amplitude mismatch coefficients via the single-azimuth ocean echoes to implement amplitude calibration, and estimates channel phase mismatch coefficients via the single-azimuth ocean echoes after amplitude calibration and the known array position information to implement phase calibration.