This thesis presents novel devices and techniques for 5G applications. First, a linearly-polarized leaky-wave antenna array front-end is demonstrated at 60 GHz for real-time beam-switching for 5G communications applications. Second, an integrated analog spectrum analyzer is demonstrated over the unlicensed IEEE 802.11ad 5G band (57-64 GHz) with a nominal physical resolution of 1 GHz. Thirdly, optically transparent and ink minimized frequency selective surfaces (FSS) screen-printed on Polyethylene Terephthalate (PET) at 28 GHz are proposed and experimentally demonstrated. Finally, a technique for the phase-only synthesis of multi-beam patterns in reflective metasurfaces based on a direct Fourier transform mapping of the near-field to far field is shown. These variety of proposed technologies provide an attractive solution to difficulties faced in common 5G applications such as spectral filtering, fundamental signal processing operations, and short-range indoor communications.