Cheng-Wu TingTzong-Lin Wu2025-03-272025-03-272025-03https://scholars.lib.ntu.edu.tw/handle/123456789/726152[SDGs]SDG13Millimeter-Wave Narrow-Width Directional Couplers on Via-Free Ridge AFSIW Technologyjournal article10.1109/tcpmt.2025.3538522