Directive millimetrewave antennas using freeformed ceramic metamaterials in planar and cylindrical forms

In this paper, we presented applications of millimetrewave EBG structures fabricated using a rapid prototyping technique based on extrusion freeforming. Numerical simulations were performed for the design of millimetrewave woodpile structures. The fabricated woodpile structures have been measured and showed a good agreement with the simulated results. A directive millimetrewave antenna utilising freeformed EBG superstrate with tapered reflectance has been demonstrated. The new EBG superstrate achieves reduced side lobes by reducing the reflection from the edges. We have fabricated for the first time the cylindrical EBG structures and designed a directive fanbeam antenna for high data rate indoor wireless applications at millimetrewave frequencies. The extrusion freeforming is a flexible and versatile technique for realising various non-homogeneous 3D bandgap structures with arbitrary geometries at millimetrewave bands.