A signal transceiver apparatus includes at least one plug-in card and a backplane. The plug-in card includes two waveguide boards, a multi-layer circuit board disposed between the two waveguide boards, and an antenna array and a first waveguide interface that are mounted on each of the two waveguide boards. A waveguide slot is provided on one side, facing the multi-layer circuit board, of each of the two waveguide boards. A metal layer corresponding to the waveguide slot is disposed on each of two sides of the multi-layer circuit board, wherein the metal layers and the waveguide slots cooperate to form two waveguide channels that are respectively located on two sides of the multi-layer circuit board and that each are connected to the antenna array and the first waveguide interface.