International audienceThe 'Split aperture decoupling' method is applied for the first time to the multi-beam pillbox antenna. This method allows simultaneously a large angular coverage, high crossing level and low side lobes levels (SLLs) for a lossless multi-beam antenna system. To validate the proposed concept a SIW (Substrate Integrated Waveguide) pillbox antenna with two radiating apertures was designed at 24.15 GHz and fabricated with a standard PCB fabrication process. The measured results of the realized prototype are in good agreement with the simulated ones. The antenna has very good scanning performance with a large angular coverage of ± 40 high crossing level between the beams around -3dB and SLLs lower than -11dB over the whole ...