Abstract—A novel coupled T-matrix and microwave network approach is proposed for the multiple scattering from parallel semicircular channels. First, an equivalent network is set up to derive the T-matrix of a single channel, in which the S-parameters are derived for the semicircular boundary and the T-matrix of the inclusive cylinders is served as loading matrix of s-parameters. In addition, the T-matrix of the inclusive cylinders is obtained from the T-matrix of each cylinder in its local coordinates using the addition theorem of cylindrical harmonics. Thus, the T-matrix description of semicircular channels could be obtained steadily by the equivalent microwave network theory. Second, the addition theorems in half space are derived and utilized to take account of multiple scattering from several parallel channels. Comparing with previous dual-series eigenfunction solutions, the coupled method simplifies the analysis and could handle much more complex structures step by step. The method is verified by comparison with previous publications and both TM and TE wave illumination are considered.