Multiple-beam antenna system with active modules and digital beam-forming

Abstract

Such a system typically comprises: a plurality of elementary antennas configured in an array, each having an associated active module, a plurality of DBF modules, each receiving a microwave signal coming from the active modules and delivering complex digital data (I, Q) representing the input signal; and DBF processor means preparing weighted sums on the basis of this complex digital data, the weighting corresponding to a reception channel defining a narrow beam of the radiation pattern of the antenna. The system further comprises a plurality of prefiltering spatial circuits, each of which receives a plurality of signals coming from the active module and delivers, to an associated DBF module, a signal which is a sum, weighted in amplitude, of certain of the signals received at input, each DBF module being thus associated with a sub-array, the different sub-arrays thus forming being imbricated with one another and the weighting being chosen so that the pattern of the sub-array is a sectoral pattern that essentially lets through only the signals coming from a restricted zone of space. The number of spatial prefiltering circuits and DBF modules is smaller than that of the elementary antennas, and the processor means simultaneously process the outputs signals from the spatial prefiltering circuits so as to obtain, for the radiation pattern of the antenna, an equivalent number of simultaneous, distinct beams of homogeneous quality.