This Small Business Innovation Research (SBIR) Phase II project will develop new materials engineered for microwave electronics. As microwave applications expand, including portable wireless devices, and as digital integrated circuit speeds and clock rates increase to the millimeter wave (MMW) range, the need arises for low-loss elements of microwave/MMW interconnects (EMIs) with properties uniform over a broad range of frequencies and environmental conditions. A new technique is now sought to embed EMIs based on Photonic Band Gap Structures (PBSs) in ceramic substrates at an early stage of fabrication. PBSs will reduce radiative losses in devices fabricated using the Low Temperature Co-fired Ceramic On Metal technique by preventing radiation leakage and by minimizing undesired scattering. The result will be improved performance, without increasing manufacturing costs. Phase I designed, fabricated, and tested PBS-based EMIs, wherein, cross waveguides with low cross talk were successfully tested. Phase II will automate the design and production of devices that include PBS EMIs. The technology will be demonstrated through the design and fabrication of a MMW antenna based on PBS.<br/><br/>A PBS will lead to quite new applications: frequency-band controlled filters, perfect channel-drop filters, point-defect resonant cavities, line-defect ninety-degree waveguide bends, waveguide intersections with low crosstalk, and others. The new technique will be employed in high-volume production items for applications such as automotive radars, avionics, as well as in a variety of broadband wireless communication devices.