Diagonal fan with outlet guide vane device

A diagonal fan has an electric motor, housing, and diagonal impeller, which is accommodated within the housing, can be driven via the electric motor, and generates a diagonal flow during operation that is deflected in an axial flow direction by an inner wall of the housing. Outlet guide vane device with a plurality of guide vanes distributed in the circumferential direction is arranged adjacently to the diagonal impeller when viewed in the axial flow direction, and homogenizes airflow generated by the diagonal impeller. Guide vanes have a radial extension from a hub region of the outlet guide vane device to the housing. An imaginary extension in the outflow angle of the diagonal impeller strikes the inner wall of the housing at an axial distance K from the diagonal impeller. Outlet guide vane device is arranged at axial distance H to diagonal impeller where 0.75≤K/H≤1.25.