A system-level study was conducted that evaluated the system performance of various dense and sparse antenna array configurations for application in millimeter-wave multi-user multiple-input multiple-output base stations. The performance was evaluated by investigating the probability that a user experiences an outage when a zero-forcing pre-coder is used in a random line of sight scenario. This paper shows that the outage probability significantly decreased when irregular sparse arrays were used rather than regular sparse or regular dense arrays. A re-configurable linear array was designed and realized as a demonstrator. It used 3D-printed aluminum box horn antenna elements that had wide scanning range in the azimuthal plane and a small sca...