Large experimental bandpass waveguide in 3D EBG woodpile manufactured by layer-by-layer ceramic stereolithography

An original waveguide located in a woodpile (layer-by-layer) crystal is presented in this paper. Its geometrical sizes, shape and location have been optimized in order to maximize its bandwidth and the matching between this guide and the input/ouput feeding WR waveguides. The 3D electromagnetic band gap (EBG) crystal has been designed, optimized and manufactured in one monolithic piece with zirconia (epsiv_r=31.2 at 30 GHz) by the 3D ceramic stereolithography process. It experimentally exhibits a large complete bandgap superior to 20% and the waveguide located in such woodpile provides a measured 20% bandwidth around 26 GHz while keeping a return loss inferior to -10dB.