Metasurfaces are artificial composite materials with subwavelength inclusions which have been shown to enable very versatile manipulation of electromagnetic waves. Particularly at microwave frequencies, the concept is widely explored and the scope of previous methods of wavefront manipulation such as frequency selective surfaces and leaky-wave antennas has been largely extended. Emerging applications like next generation wireless communication and radar sensing could benefit from novel metasurface-based antennas which have been recently proposed. Although most of these emerging applications use frequencies of operation in the millimeter wave (mm-wave) band, research on metasurfaces in this band is still scarce. Many secondary effects known in the microwave community such as fabrication constraints and material losses are more severe using mm-waves and they significantly hamper the development of efficient devices. The aim of this thesis is to investigate metasurface architectures suited for mm-wave frequencies and to explore promising related antenna concepts. Causes for significant performance degradation in printed circuit metasurfaces for mm-waves are identified and synthesis techniques with which they can be minimized are proposed. The effectiveness of the proposed synthesis framework is verified by comprehensive experimental works. Building on this synthesis approach, two kinds of antenna systems are experimentally demonstrated, based on transmissive metasurfaces and on leaky-wave antennas. Co-sponsored by: Advanced Electromagnetics Group, UNSW Canberra Speaker(s): Andreas Olk, Virtual: https://events.vtools.ieee.org/m/279361