This paper derives useful expressions for the synthesized beam statistics using poststatistic steering (PSS), when three antennas are used in a spatial interferometer configuration for two‐dimensional steering. These antennas may have arbitrary position and can have nonorthogonal baselines. The use of three (noncollinear) antennas allows altitude dependent two‐dimensional steering. This technique is verified using spatial interferometer data obtained in October 1989 using the MU radar, including PSS in directions parallel and perpendicular to the wind direction, which is a very convenient advantage of the technique. Copyright 1990 by the American Geophysical Union.