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

摘要

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.