A radar system for reconstructing an image, the radar comprising: a heterogeneous wideband antenna array apparatus operative to receive signals characterizing a target object, the antenna array apparatus comprising a first sub-array having one or more antenna elements and a second sub-array having one or more antenna elements; and a data processing unit operative to reconstruct an image of the target object by: rendering the signals into plurality of per-frequency estimates of the target object, and generating a weighted combination of the plurality of per-frequency estimates through Minimum Mean Square Error (MMSE); wherein: the one or more antenna elements of the first sub-array have the same shape and physical dimensions in all directions as a first antenna element which is optimized to operate within a first frequency range; and the one or more antenna elements of the second sub-array have the same shape and physical dimensions in all directions as a second antenna element which is optimized to operate within a second frequency range; the first antenna element differs in at least one physical dimension from the second antenna element, such that the first frequency range is different from the second frequency range; the first frequency range and the second frequency range overlap; antenna elements of the first sub-array and antenna elements of the second sub-array are interleaved such that at least one antenna element of the first sub-array is surrounded by antenna elements of the second sub-array. a heterogeneous wideband antenna array apparatus operative to receive signals characterizing a target object, the antenna array apparatus comprising a first sub-array having one or more antenna elements and a second sub-array having one or more antenna elements; and a data processing unit operative to reconstruct an image of the target object by: rendering the signals into plurality of per-frequency estimates of the target object, and generating a weighted combination of the plurality of per-frequency estimates through Minimum Mean Square Error (MMSE); wherein: the one or more antenna elements of the first sub-array have the same shape and physical dimensions in all directions as a first antenna element which is optimized to operate within a first frequency range; and the one or more antenna elements of the second sub-array have the same shape and physical dimensions in all directions as a second antenna element which is optimized to operate within a second frequency range; the first antenna element differs in at least one physical dimension from the second antenna element, such that the first frequency range is different from the second frequency range; the first frequency range and the second frequency range overlap; antenna elements of the first sub-array and antenna elements of the second sub-array are interleaved such that at least one antenna element of the first sub-array is surrounded by antenna elements of the second sub-array. the one or more antenna elements of the first sub-array have the same shape and physical dimensions in all directions as a first antenna element which is optimized to operate within a first frequency range; and the one or more antenna elements of the second sub-array have the same shape and physical dimensions in all directions as a second antenna element which is optimized to operate within a second frequency range; the first antenna element differs in at least one physical dimension from the second antenna element, such that the first frequency range is different from the second frequency range; the first frequency range and the second frequency range overlap; antenna elements of the first sub-array and antenna elements of the second sub-array are interleaved such that at least one antenna element of the first sub-array is surrounded by antenna elements of the second sub-array. <EOS>