Many systems are integrating capabilities that require mmWave beamforming. Example application areas include suites of sensors, 5G/6G systems, radar, and SATCOM. In this presentation, a review of best design practices surrounding interconnect design required to route signals into phased array structures required in these application areas will be presented. The core of this presentation will examine the process and theory required to design transmission lines and antenna arrays for these systems. In addition to transmission lines for these systems, the placement and arrangement of antennas in the array, as well as oscillator and transceiver elements, will determine the beamforming capabilities of these systems. Examples from industry and research literature will be presented to illustrate practical usage of these concepts and the diversity of systems to which they apply.