The Andenes-MF-radar on Andøya operates at 1.98 MHz with a peak power of 50 kW.  27 µs long electromagnetic pulses are vertically transmitted into the ionosphere via a transmitting antenna. These pulses are partially reflected at irregularities of the refractive index and are received by three spatially separated receiving antennas. From the three received data series the mesospheric wind field is derived by a correlation method (Spaced Antenna Method, SA) after elimination of disturbances caused by foreign radio transmitters.