Direction and polarization estimation using arrays with small loops and short dipoles

It is shown that when polarization-sensitive arrays consisting of crossed small loops and short dipoles are used, one can eliminate the requirement in the ESPRIT algorithm that sensors must occur in matched pairs. The dipoles and loops are sensitive to the polarizations of incident electromagnetic plane waves. The dipoles are sensitive to the incident electric field components, and the loops to magnetic field components of the incident waves. The invariance properties among the dipole and loop outputs of an arbitrary array of orthogonal loops and orthogonal dipoles are exploited to compute both the two-dimensional arrival angles and polarizations of incoming narrowband signals. It is shown that with dipoles and loops, vertical arrays are not necessary to obtain good direction estimates for signals from low angles