In recent years, additive manufacturing has found increasing interest in fabrication of dielectric antennas. Using additive manufacturing brings significant advantages such as design flexibility, compactness, fast and low-cost manufacturing compared to traditional fabrication methods. Dielectric antennas having dense material allow high power transfer efficiency through the lens. However, a successful 3D printing process with dense dielectric materials is a great challenge. In this paper, impact of main process parameters during 3D printing; namely printing speed, process temperature and layer height on the resulted relative electrical permittivity values of a dense dielectric material is investigated. Test samples are printed with a dielectric material having εr = 10, and relative permittivity variations of these samples are measured with a vector network analyzer in X-band (8.2-12.4 GHz). In this way, optimum printing parameters are determined. Influence of dielectric constants of printed materials on the antenna radiation characteristics are inspected for an extended hemispherical lens antenna by a full-wave computer-aided design tool. Results demonstrate that an additively manufactured dense dielectric antenna will act as a traditionally manufactured dielectric antenna if and only if it is manufactured with optimum printing parameters.