This paper addresses the issue of constructing millimeter band antennas using dielectric waveguide structures. A new type of linear antenna, incorporating metal pins on the side walls of the grooved dielectric waveguide, is proposed for generating polarization perpendicular to the waveguide axis. However, these antennas suffer from the drawback of cross-polarized radiation in directions close to the waveguide axis. To overcome this limitation, a modified antenna design with transverse polarization is introduced, featuring a closed groove waveguide with a longitudinal slot in the top of wall. The paper provides a comparison between two types of dielectric waveguide antennas. First, waveguide antenna with grooves in the dielectric which resulting longitudinal polarization, and second, waveguide antenna with quarter-wavelength pins which resulting transverse polarization. Electrodynamic modeling data is provided to demonstrate the effectiveness of the proposed antennas for satellite, 5G antenna, and radar applications. Finally, antenna of quarter-wavelength pins is proposed with frequency of 39GHz, gain of 19.8dBi, width of radiation pattern of 3.2\(^{\circ}\) and side lobe level (SLL) of -13.3dB has been achieved.