The Leibniz-Institute of Atmospheric Physics in Kühlungsborn, Germany (IAP) is installing a new pow-erful VHF radar on the North-Norwegian island Andøya (69.30 • N, 16.04 • E) in 2009/2010. The new Middle Atmosphere Alomar Radar System (MAARSY) replaces the existing ALWIN radar which has been operated continu-ously on Andøya for more than 10 years. The new system is a monostatic radar operated at 53.5 MHz with an active phased array antenna consisting of 433 Yagi antennas. The 3-element Yagi antennas are arranged in an equilateral triangle grid forming a circular aperture of approximately 6300 m 2 . Each individual antenna is connected to its own transceiver with independent phase control and a scalable output up to 2 kW. This arrangement allows very high flexibility of beam forming and beam steering with a symmetric radar beam of a minimum half power beam width of 3.6 • , a maximum di-rective gain of 33.5 dB and a total transmitted peak power of approximately 800kW. The IF signals of each 7 transceivers connected to each 7 antennas arranged in a hexagon are com-bined to 61 receiving channels. Selected channels or combi-nations of IF signals are sent to a 16-channel data acquisition system with 25 m sampling resolution and 16-bit digitization specified which will be upgraded to 64 channels in the final stage. The high flexibility of the new system allows classical Doppler beam swinging as well as experiments with simulta-neously formed multiple beams and the use of modern inter-ferometric applications for improved studies of the Arctic at-mosphere from the troposphere up to the lower thermosphere with high spatiotemporal resolution. Fig. 1. Sketch of the antenna array of MAARSY. Each cross rep-resents crossed three-element Yagi antennas mounted on a concrete block (small boxes). The six rectangles outside the array, indicated as A–F, represent containers accommodating the transmit-receive modules.