Abstract: A scanning radio-frequency direction finder which includes two synchronously scanned beams (antenna patterns) having their boresite (symmetry) axes angularly offset by a predetermined amount, either physically or by control of time of operation. A first of the beams is double-lobed with a null at its boresite while the second has its maximum at its boresite. The signals received through each pattern are continuously phase measured and the phase of signals through the second beam is stored when the received signal strength therethrough reaches a predetermined value. The continuously measured first beam signal phase is compared with the aforementioned stored second beam signal phase, the instantaneous scan angle of the first beam at the time of phase equality being taken as the correct angle of the target reflector or source of received signals (target). The result is much improved angle measurements, especially in elevation at low angles.