transmitting electromagnetic signals by a transmitting antenna,

receiving the transmitted electromagnetic signals reflected by an object by means of at least two essentially identical receiving antennas,

arranging said receiving antennas in a basic alignment and with a distance (d) from each other,

using receiving antennas which each have a sensitivity characteristic over reception angles showing a maximum for a reception angle coinciding with the basic alignment, flanks initially falling with increasing reception angle from the basic alignment from said maximum to a minimum each, then with still increasing reception angle from the basic alignment forming first sidelobes having increasing sensitivities, said sidelobes being arranged symmetrically to said basic alignment,

for measurement purposes, determining phase differences of the signals being reflected by an object and received by said at least two receiving antennas, said phase difference being unambiguous within a certain angle interval, said angle interval depending upon the distance (d) between the receiving antennas,

wherein said distance (d) is chosen so that limits of the unambiguous angle interval intersect the first sidelobes, and wherein the signals received by the receiving antennas are vectorially added before the phase differences are determined.