Phase based sector resolution in angle of arrival (AoA) computation using a five element circular array

Many techniques are employed to passively measure Angle of Arrival (AOA) in different EW systems viz. Amplitude Comparison, Phase Comparison, Time Difference of arrival (TDOA) and Rotary Direction Finding (RDF). `Base Line Interferometry (BLI)´ is a phase comparison technique. It is used in EW systems where high accuracy and high sensitivity are required. In this paper, a five element circular array of twisted dipoles is taken for realization of BLI based DF system. An algorithm, which uses only phase data to compute Angle of Arrival (AOA) is developed. The most critical part of this algorithm is to select the appropriate base line (sector selection) for applying the standard BLI formula. This approach offers the benefit of simpler and substantially less time-taking calibration process, when compared with correlative interferometry based systems using similar antenna system. This also offers the benefit of low form factor and less hardware (as no ADF is required) when compared with linear BLI systems.