Direction finding with mutually orthogonal antennas

Electromagnetic direction finding using a set of three mutually orthogonal antennas is studied. The vector effective height concept from antenna theory is employed to develop three direction finding algorithms for use with the proposed antenna arrangement. The first algorithm estimates the direction-of-arrival by computing a vector that is perpendicular to the locus of the instantaneous electric field vector measured at the origin of the coordinate system. The second and third algorithms are based on the well-known maximum likelihood and MUSIC algorithms. For all algorithms we assume a narrowband signal model and that multiple incident waves can be separated in the frequency domain before processing each signal separately. In simulation, each algorithm successfully located the direction-of-arrival to within 2° for circularly polarized waves at SNR ≥ 35dB.