A multibeam antenna based on substrate integrated waveguide technology for MIMO wireless communications

A 24-beams slot array antenna, which achieves 360-degrees coverage over azimuth direction, based on substrate integrated waveguide (SIW) technology is designed, fabricated and measured for supporting the concept of triangle cell, beam diversity and multiple input multiple output (MIMO) wireless communications. Constructed by six 4-beams single layer SIW antennas which integrate the 4 x 8 modified Butler matrix with a low side lobe level (SLL) amplitude distribution, measured SLLs are reduced as low as -14.5 dB for all beams in E-plane. The size of the SIW single layer multibeam antenna is 385 mm x 110 mm including feeding network. The usable bandwidth of the proposed antenna is 3.75% at 16 GHz. Index Terms--Beam-forming, Butler matrix, substrate integrated waveguide (SIW).