The effects of mutual coupling using a linear array of thin dipoles of finite length

The effects of mutual coupling on the direction finding accuracy of a linear array of dipole elements are studied. An approximative expression of the measured voltages when a plane wave is incident upon the array is derived using mutual impedances. The direction finding accuracy is then investigated by calculating the Cramer-Rao lower bound. It is found that a known coupling does not affect the estimation performance much. In the case of an unknown coupling, the estimation procedure can be simplified by using only a few off-diagonal elements of the coupling matrix. Depending on how many parameters are included, the RMS error can actually be smaller than the CRB for the case when all off-diagonals are estimated