A radar system comprising at least processing means, an emission antenna and a reception antenna formed by an array (31, 32, 33) of radiating elements, the configuration of said array being characterised by a set of parameters that determine its geometric shape, the number of radiating elements and the step between the radiating elements, the radiating pattern of said antenna being determined to maximise the antenna gain, the configuration of said array being defined according to the following steps: - a first preliminary step of selecting a basic configuration of said array; - a first step of determining the expected signal of a target in said directions P; - a second step of determining the addition, for each of said directions P, of the signals received by each radiating element so as to maximise the signal-to-noise ratio at the output of said addition; - a third step of computing a quality factor as a function of the signal-to-noise ratios (S/N) received on said directions P; - a fourth step of varying the parameters of said array; - a next step of determining the definitive configuration as being that which, among the tested configurations, maximises the quality factor, the preceding steps being repeated as long as the maximum quality factor is not reached; said system being characterised in that, with the antennae beams being computed in directions P by an ABF function: - the possible detections of a target by the secondary lobes of one or more beams formed by ABF are processed by said processing means using an algorithm that is based on comparing the power levels of the echoes detected by said received beams in a distance-speed resolution cell of the radar, with at most one detection not being possible per distance-speed resolution cell; - said processing means use the hypothesis that it is unlikely that more than one echo of the signal-to-noise ratio (S/N) can exist that is big enough for it to be detectable, for a given resolution cell of said radar, either by speed, by distance or by distance-speed, depending on the processing that is implemented; - if there is more than one detectable echo per resolution cell among the plurality of beams formed by ABF, only the echo and ABF procuring the maximum power or the maximum signal-to-noise ratio (S/N) are considered to be valid. - a first preliminary step of selecting a basic configuration of said array; - a first step of determining the expected signal of a target in said directions P; - a second step of determining the addition, for each of said directions P, of the signals received by each radiating element so as to maximise the signal-to-noise ratio at the output of said addition; - a third step of computing a quality factor as a function of the signal-to-noise ratios (S/N) received on said directions P; - a fourth step of varying the parameters of said array; - a next step of determining the definitive configuration as being that which, among the tested configurations, maximises the quality factor, the preceding steps being repeated as long as the maximum quality factor is not reached; - the possible detections of a target by the secondary lobes of one or more beams formed by ABF are processed by said processing means using an algorithm that is based on comparing the power levels of the echoes detected by said received beams in a distance-speed resolution cell of the radar, with at most one detection not being possible per distance-speed resolution cell; - said processing means use the hypothesis that it is unlikely that more than one echo of the signal-to-noise ratio (S/N) can exist that is big enough for it to be detectable, for a given resolution cell of said radar, either by speed, by distance or by distance-speed, depending on the processing that is implemented; - if there is more than one detectable echo per resolution cell among the plurality of beams formed by ABF, only the echo and ABF procuring the maximum power or the maximum signal-to-noise ratio (S/N) are considered to be valid.