Waveguide to planar surface integrated waveguide and planar stripline transitions

An apparatus comprising:

• a substrate assembly having a first side and a second side;
• a waveguide antenna element positioned on the first side of the substrate assembly;
• a microstrip line positioned within the substrate assembly, wherein the waveguide antenna element overlaps the microstrip line;
• a stripline positioned within the substrate assembly and electrically connected to the microstrip line;
• a first conductive plane positioned on the first side of the substrate assembly and overlapping the stripline;
• and
• a second conductive plane positioned on the second side of the substrate assembly and overlapping both the microstrip line and the stripline.

A method comprising:

• forming a waveguide antenna element and a first conductive plane on a first substrate;
• forming a microstrip line on a second substrate;
• forming a second conductive plane on a third substrate;
• and
• assembling at least the first substrate, the second substrate, and the third substrate to form a substrate assembly, wherein the substrate assembly defines a transmission device, and wherein the microstrip line is electrically connected to the transmission device.