An antenna and system for determining two-dimensional angle-of-arrival includes circular array interferometers for azimuth, linear interferometers for elevation, and a mast for positioning the interferometers in a vertically stacked orientation. The circular array interferometers exhibit azimuth constant-phase-difference contours orthogonal to elevation constant-phase-difference contours exhibited by the linear interferometers. An antenna and system for determining azimuth of input signals includes ambiguous and non-ambiguous circular array interferometers. The non-ambiguous circular array interferometer resolves ambiguities introduced by the ambiguous circular array interferometer, the at least one ambiguous circular array interferometer operatively coupled to a low-order Butler matrix and power divider/combiner such that a high order Butler matrix is not required to generate omnidirectional phase modes from the ambiguous circular array interferometer. A method for determining phase differences indicative of two-dimensional angle-of-arrival includes determining a first phase difference indicating azimuth using circular array interferometers, determining a second phase difference indicating elevation using linear interferometers, and orienting the interferometers in a vertically stacked orientation such that the azimuth constant-phase-difference contours are orthogonal to the elevation constant-phase-difference contours. A method for determining phase difference representative of azimuth includes determining a phase difference indicative of azimuth using ambiguous circular array interferometer and non-ambiguous circular array interferometers, and resolving ambiguities in azimuth introduced by the ambiguous circular array interferometer using the non-ambiguous circular array interferometer, the at least one ambiguous circular array interferometer operatively coupled to a low-order Butler matrix and power divider/combiner such that a high order Butler matrix is not required to generate omnidirectional phase modes from the ambiguous circular array interferometer. A method for determination of polarization of input signals with only one added element.