The realization of high isolation and wide band 4×4 microstrip Butler matrix

A high isolation and wideband 4 × 4 Butler matrix is designed and fabricated on a single-layer PCB substrate in this paper, which covers the frequency band from 1.92 to 2.17 GHz. The measured S-parameters show that its return loss and isolation are better than -23 dB and -26 dB, respectively, with its good performance achieved for real application.