A millimeter-wave solid-state power combining circuit based on branch-waveguide directional coupler

A new Ka-band (32-37 GHz) eight-way solid-state power combining amplifier using branch-waveguide directional coupler is proposed in this paper. By using low-loss waveguide power dividing/combining network and a monolithic microwave integrated circuit(MMIC) with a low-loss microstrip-to-waveguide transition, a high combining efficiency larger than 80% from 32 GHz to 37 GHz is achieved. With a compact structure, an easy fabrication process, and good thermal property, the power combining network could be used in millimeter-wave solid state high power combining for high efficiency in a broad-band.