Millimetrewave Metamaterials with Controlled Defects and Their Applications

In this paper, we presented several applications of millimetrewave EBG structures with controlled defects, 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. Freeformed EBG structures with controlled defects can be used for various millimetrewave components such as waveguides and filters. The extrusion freeforming is a flexible and versatile technique for realising various non-homogeneous 3D bandgap structures at millimetrewave bands.