Reduced sidelobe multibeam antenna array with broadside beam fed by 4?8 Butler matrix

A concept of sidelobe level reduction in multibeam antennas fed by 4 × N Butler matrices has been extended on multibeam antennas with broadside beam. It has been shown that by adding in-phase power dividers at the output of a Butler matrix ensuring ±90°, 0° and 180° differential phases and by increasing the number of radiating elements a significant sidelobe reduction can be achieved, similarly as in case of known multibeam antennas fed by modified Butler matrices. The presented concept has been confirmed by measurements of a multibeam antenna array consisting of eight radiating elements fed by 4 × 8 modified Butler matrix in which the achieved sidelobe level is as low as -22 dB.