An antenna system for transducing radio-frequency energy includes: a first antenna sub-system comprising a plurality of radiators and a ground conductor, each of the plurality of radiators being sized and shaped to transduce millimeter-wave energy between first wireless signals and first electrical current signals; and a second antenna sub-system comprising a first radiator configured to transduce sub-6 GHz energy between second wireless signals and second electrical current signals, wherein the first radiator comprises the ground conductor.