Consideration of sectors for direction of arrival estimation with circular arrays

A precise knowledge of the electromagnetic receiving characteristics of the antenna is mandatory for a precise determination of the directions of the impinging signals. For circular arrays the phase-mode description is an effective way of approximating the receiving characteristics of the antenna elements. For antenna elements, which are mounted in front of a cone-shaped reflector, angular ranges are defined to reduce the coupling and scattering influences. In these angular ranges, the receiving characteristics are more robust towards changes in the antenna structure and can be well approximated by a small number of phase-modes. The limitation of the angular range per element leads to the sector concept for DOA estimation. Especially the combination of the Virtual Array concept with the sector concept increases the robustness of the DOA estimation approaches against array imperfections.