High precision DOA estimation of SSR transponder signals

In this work, localization by means of DOA (Direction of Arrival) estimation is investigated. A newly developed low-cost planar linear array and improved receiver hardware is calibrated and evaluated by the use of a dedicated measurement aircraft, not based on ADS-B (Automated Dependent Surveillance-Broadcast) airborne position telegrams. It will be shown how this DOA sensor closely approaches theoretic precision limits.