DOA estimation in consideration of the array element pattern

We clarify the cause of error for Direction-Of-Arrival (DOA) estimation by MUSIC and ESPRIT algorithm. In MUSIC, using a measured steering vector could compensate for these errors, however accurate measurement of antenna complex radiation pattern is difficult and often an ideal steering vector is used in DOA estimation. In ESPRIT, two identical subarrays, a linear uniform array composed of overlapping subarrays, are often used. These ideal assumptions are seriously affected by the mutual coupling between elements and the inaccuracy of the element position, and the resulting estimation errors. Computer simulations and measurements using an 8.45 GHz DBF antenna system give a quantitative discussion for the DOA estimation error.