The design, fabrication and measured performance of an all-dielectric Terahertz (THz) horn antenna based on hollow-core electromagnetic crystal structure is described. Simulation result shows that the antenna works above 100 GHz, with better than 30 dB return loss and highly directional radiation pattern. Fabrication of the antenna is implemented by a THz polymer jetting rapid prototyping method. Characterization of this antenna is performed using a THz time-domain spectrometer (TDS). Measurement results for the far-field radiation patterns are compared with simulation results. © 2013 EurAAP.