An apparatus is provided. There is a circuit assembly with a package substrate and an integrated circuit (IC). The package substrate has a microstrip line, and the IC is secured to the package substrate and is electrically coupled to the microstrip line. A circuit board is also secured to the package substrate. A dielectric waveguide is secured to the circuit board. The dielectric waveguide has a dielectric core that extends into a transition region located between the dielectric waveguide and the microstrip line, and the microstrip line is configured to form a communication link with the dielectric waveguide.