A mm-wave antenna apparatus with beam steering function that includes: a Butler Matrix feeding network; a plurality of power combiners, each power combiner having one input and N outputs, configured to apply equal phase and power to a phase distributed output signal generated by the Butler Matrix feeding network and to generate N processed signals; and a plurality of millimeter wave switched beam planar antenna arrays having at least 1.5 GHz of bandwidth and located on a top low loss dielectric substrate, each antenna array of N elements, configured to obtain direct and narrow width beams from the N processed signals combined by each power combiner.