This thesis was initiated by the University of Oslo at the Department of Informatics. The field of study regarding snow analysis, characterization and imaging of snow layers, has been an ongoing study-field at the Department of Geophysics for some years. The transverse collaboration project, Land-ATmosphere Interactions in Cold Environment (LATICE) seeks new advanced instruments for characterizing the impact of climate changes to the snow. In this thesis, 3D printed high gain, ultra-wideband antennas for snow-penetrating radar applications has been simulated and manufactured. A custom build stepped ridge horn antenna was found to be best suited regarding large bandwidth and high gain that covers the entire band. Two antennas have been constructed and characterized for a gain between 10 dBi to 15 dBi covering the range between 2.3 GHz to 6.1 GHz. The antennas are 3D printed in low cost polylactic acid (PLA) and coated with conductive copper spray. The measured half-power beamwidth for the first printed antenna is 26◦ in the E-plane and 26◦ in the H-plane. For the second printed antenna, the half-power beamwidth is 24◦ in the E-plane and 28◦ in the H-plane. Measured peak directivity is 12.6 dBi and 12 dBi, and the front-to-back ratio is 22 dB and 24 dB for the first and second antenna, respectively. In addition, a new technique for feeding 3D printed waveguide structures are presented. The work on this feeding technique has been submitted to the IEEE MTT-S International Microwave Workshop Series on Advanced Materials and Processes (IMWS-AMP) conference in September 20-22, 2017 (Appendix A). The antennas have been tested together with the Novelda X2 Ventricorder module at the snow lab at the Department of Informatics, and outdoor measurements at Finse Alpine Research Center, Norway. Promising results has been achieved from these measurements. The radar is able to detect different layers of pressed wood with a measured permittivity of 1.89. Results from the outdoor measurements has been shown in the end of the thesis, but not verified due to limited time.