Microelectronic Device Package Including Antenna Horn and Semiconductor Device

An example semiconductor package comprises a patch antenna formed in a first conductor layer of a multilayer package substrate. The multilayer package substrate comprises conductor layers spaced from one another by dielectric material and coupled to one another by conductive vertical connection layers. The multilayer package substrate has a board side surface opposite a device side surface. The semiconductor package further comprises a semiconductor die mounted to the device side surface of the multilayer package substrate spaced from and coupled to the patch antenna. An antenna horn is mounted to the device side surface and aligned with the patch antenna using a mounting structure. The semiconductor package further comprises a reflector formed on a second conductor layer in the multilayer package substrate. The second conductor layer is positioned closer to the board side surface of the multilayer package substrate compared to the patch antenna.