An electronic device includes a multilevel package substrate with a horizontal substrate integrated waveguide (SIW) with a channel, a vertical SIW with an opening, a grounded coplanar waveguide (GCPW), a first transition between the horizontal SIW and the GCPW, and a second transition between the horizontal and vertical SIWs, as well as a semiconductor die having conductive structures coupled to a signal trace and a ground trace of the GCPW, and a package structure that encloses the semiconductor die and a portion of the multilevel package substrate.

A method of fabricating an electronic device including fabricating a multilevel package substrate with first, second, third, and fourth levels, a semiconductor die mounted to the first level, and fabricating a conductor backed coplanar waveguide transmission line feed with an interconnect and a conductor, the interconnect including coplanar first, second, and third conductive lines extending in the first level along a first direction from respective ends to an antenna, the second and third conductive lines spaced apart from opposite sides of the first conductive line along an orthogonal second direction, and the conductor extending in the third level under the interconnect and under the antenna.