A radio frequency (RF) assembly that includes a microstrip to waveguide transition is described herein. In one example, the RF assembly can include a substrate, a microstrip, and a waveguide. The substrate can include an antenna that includes an antenna slot. A portion of the microstrip, such as an end of the microstrip, can be disposed within and/or underneath the antenna slot. The microstrip can be embedded within the substrate and can be electrically coupled to the antenna. At least a portion of the waveguide can be disposed over the antenna slot.