Control of microwave emission from electromagnetic crystals by lattice modifications

Millimeter order electromagnetic crystals composed of epoxy lattices containing titania-based particles and having a three-dimensional diamond structure were fabricated by using a stereolithograpy process. The diamond lattice structure formed a perfect bandgap to microwave transmission, while the directional diamond structures with stretched lattice spacing showed the directional transmission of microwaves. The stretching ratio of the lattice spacing was changed according to the band calculation using a plane wave propagation method. A microwave antenna head composed of normal and stretched diamond structures was fabricated which achieved unidirectional transmission.