Low-order linear array for FM passive radar: calibration and beamforming

An array factor models the ideal response of an antenna array to the far field source. In order to coherently add a far-field signal array factor model must be known. However, the model does not include errors that are encountered in reality. This discrepancy leads to significant loss of coherent gain of the array. This paper describes an array calibration method we used for compensating error in our 4-antenna FM linear array. We show the improvement we got using the error compensation method in direction finding as well as array pattern from real signals.