Wideband two dimensional interferometric direction finding algorithm using base-triangles and a proposed minimum planar array

Abstract

In wideband interferometric direction finding ambiguity is inevitable due to practical antenna array dimensions. A new algorithm for wideband interferometer direction finding is developed to resolve the ambiguity problem with minimum number of antennas. The method is based on direction finding by three antennas arranged at the three vertices of a triangle named the base-triangle. A two dimensional matrix of ambiguous angles is generated. The ambiguity problem is resolved by an auxiliary base-triangle formed by a fourth antenna in the arrangement. The common angle between the two ambiguous directions derived from the two base-triangles, is the desired angle. As such a four antenna array is optimized with the proposed algorithm to minimize the direction finding error through the 6–18 GHz frequency band for different signal to noise ratios and in the presence of channel phase tracking error. The array performance is evaluated through Monte-Carlo simulations for a coverage of ±45° azimuth and ±45° elevation and a polynomial expression is fitted to the evaluated Root Mean Square errors. Finally, a comparison is made between the proposed method and various correlative interferometer methods. The method has an accuracy better or equal to the cosine function correlative interferometer with much less computation time.