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Fig. 1

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Three successive zoom-outs showing the stations in the LOFAR core. The different scales of the hierarchically organised HBA elements are highlighted and their respective beam sizes are shown. The large circular area marks the edge of the Superterp, which contains the inner-most 6 stations (i.e. 12 HBA sub-stations: where there are 2 sub-stations, each of 24 tiles, in each HBA core station); other core stations can be seen highlighted beyond the Superterp in the third panel. Left: a single HBA tile and associated beam. Middle: a single HBA sub-station with three simultaneous station beams. Right: the 6 stations of the Superterp plus 3 core stations in the background are highlighted. Four independent beams formed from the coherent combination of all 24 core HBA stations, most of which are outside this photo, are shown. For the LBA stations, a similar scheme applies except that each LBA dipole can effectively see the whole sky. Fields of the relatively sparsely distributed LBA antennas are visible in between the highlighted HBA stations in all three panels.

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