DESIGN AND ANALYSIS OF DIRECTION-OF-ARRIVAL ESTIMATION SYSTEMS USING ELECTRICALLY SMALL ANTENNA ARRAYS BY

The first direction-of-arrival systems were based on amplitude measurements of signals received from a single, nonstationary antenna. Next generation sys-tems depended on phase measurements for direction-of-arrival information. With the advent of DSP-based direction finding, a return to amplitude-based measurements is possible. This enables direction-of-arrival estimation using arrays whose interelement phase difference is very small or even negligible. Traditionally, direction-finding systems have been quite large to ensure a re-solvable phase delay between elements. Since the direction-finding arrays presented here are much less reliant on interelement phase delay, their foot-prints can be dramatically reduced. Electrically small antennas have the radiation pattern of an electric dipole, a magnetic dipole, or some superpo-sition of the two. Orthogonally oriented electrically small antennas receive with very distinct patterns when combined in an array, provided that the mutual coupling is small. With six elements measuring the Cartesian com