A waveguide interface comprising: a launch transducer ( 16, 26) comprising one or more transmission lines (261, 262, 265, 266) in a first portion of the launch transducer and at least one antenna element (267, 268, 168, 169, 171, 172) coupled to the one or more transmission lines in a second portion of the launch transducer, wherein the at least one antenna element is configured to radiate millimeter wave frequency signals; a support block including a printed circuit board (11, 21), the support block oriented along a plane; a communication device (12, 22) coupled to the printed circuit board, wherein the launch transducer is positioned adjacent to and coupled to the communication device; a circular interface plate coupled to an end of the support block and oriented perpendicular to the plane, the interface plate having a rectangular slot, wherein the interface plate is positioned flush against a standard waveguide flange such that the narrow dimension of the rectangular slot within the interface plate is orthogonal to an H-field dimension of the standard waveguide flange; and a waveguide component coupled to the interface plate, the waveguide component having a waveguide opening, wherein the first portion of the launch transducer is positioned within the rectangular slot such that the rectangular slot provides a waveguide segment having dimensions configured to provide a cutoff frequency above the operating range of the standard waveguide interface to prevent energy from the transmission line from being emitted toward the printed circuit board or the waveguide opening and to allow energy to pass from the at least one antenna element onto the waveguide opening. a launch transducer ( 16, 26) comprising one or more transmission lines (261, 262, 265, 266) in a first portion of the launch transducer and at least one antenna element (267, 268, 168, 169, 171, 172) coupled to the one or more transmission lines in a second portion of the launch transducer, wherein the at least one antenna element is configured to radiate millimeter wave frequency signals; a support block including a printed circuit board (11, 21), the support block oriented along a plane; a communication device (12, 22) coupled to the printed circuit board, wherein the launch transducer is positioned adjacent to and coupled to the communication device; a circular interface plate coupled to an end of the support block and oriented perpendicular to the plane, the interface plate having a rectangular slot, wherein the interface plate is positioned flush against a standard waveguide flange such that the narrow dimension of the rectangular slot within the interface plate is orthogonal to an H-field dimension of the standard waveguide flange; and a waveguide component coupled to the interface plate, the waveguide component having a waveguide opening, wherein the first portion of the launch transducer is positioned within the rectangular slot such that the rectangular slot provides a waveguide segment having dimensions configured to provide a cutoff frequency above the operating range of the standard waveguide interface to prevent energy from the transmission line from being emitted toward the printed circuit board or the waveguide opening and to allow energy to pass from the at least one antenna element onto the waveguide opening.