Electronic Device Having Stacked-Patch Antenna with Floating Ground Via

an electronic device may be provided with an antenna module having a substrate. an antenna may be disposed on the substrate. the antenna may have a directly fed patch and parasitic patches. the antenna may be fed by a feed via. the parasitic patches may include a first layer of parasitic patches separated by a gap overlapping the directly fed patch. the parasitic patches may include an additional parasitic patch formed in a second layer. the additional parasitic patch may overlap the gap. a floating ground via may couple a center of the additional parasitic patch and a center of the directly fed patch to a landing pad in a ground layer. the landing pad may short the via to the ground layer at the radiating frequency of the antenna. the landing pad may be electrically floating at dc frequencies.