Abstract: A T-junction plates-inserted waveguide-based power combiner is experimentally investigated, which is compact, easy to fabricate and has high power handing capacity. It consists of two overmoded rectangular waveguides which are connected vertically, and two perpendicular linearly polarized microwaves at 9.50 GHz and 9.60 GHz can be transmitted separately to realize incoherent power combining. Cold test shows that both channels of the combiner realize single-mode transmission effectively, and the transmission losses located at the joint are less than 0.4 dB. Hot test verifies the combiner’s GW level power handling capacity.