An antenna configured to receive radiation at global navigation satellite system, GNSS, frequencies, comprising: a dielectric substrate ; a circular patch overlaying the dielectric substrate; one or more antenna feeds coupled to the circular patch; and a metamaterial ground plane comprising: a plurality of conductive patches arranged along a first plane on a backside of the dielectric substrate and separated from the circular patch by the dielectric substrate, the plurality of conductive patches arranged in a pattern that provides circular symmetry with respect to a center of the antenna, at least some of the plurality of conductive patches separated from adjacent ones of the plurality of the conductive patches by a space extending radially outward; a cavity comprising a ground plane and a conductive fence , the ground plane arranged along a second plane below the first plane, and the conductive fence extending around a perimeter of the ground plane, wherein the conductive fence is spaced from the backside of the dielectric substrate and from the plurality of conductive patches by a gap; and a plurality of conductive pins each extending between the conductive fence and an upper surface of the dielectric substrate. a dielectric substrate ; a circular patch overlaying the dielectric substrate; one or more antenna feeds coupled to the circular patch; and a metamaterial ground plane comprising: a plurality of conductive patches arranged along a first plane on a backside of the dielectric substrate and separated from the circular patch by the dielectric substrate, the plurality of conductive patches arranged in a pattern that provides circular symmetry with respect to a center of the antenna, at least some of the plurality of conductive patches separated from adjacent ones of the plurality of the conductive patches by a space extending radially outward; a cavity comprising a ground plane and a conductive fence , the ground plane arranged along a second plane below the first plane, and the conductive fence extending around a perimeter of the ground plane, wherein the conductive fence is spaced from the backside of the dielectric substrate and from the plurality of conductive patches by a gap; and a plurality of conductive pins each extending between the conductive fence and an upper surface of the dielectric substrate. a plurality of conductive patches arranged along a first plane on a backside of the dielectric substrate and separated from the circular patch by the dielectric substrate, the plurality of conductive patches arranged in a pattern that provides circular symmetry with respect to a center of the antenna, at least some of the plurality of conductive patches separated from adjacent ones of the plurality of the conductive patches by a space extending radially outward; a cavity comprising a ground plane and a conductive fence , the ground plane arranged along a second plane below the first plane, and the conductive fence extending around a perimeter of the ground plane, wherein the conductive fence is spaced from the backside of the dielectric substrate and from the plurality of conductive patches by a gap; and a plurality of conductive pins each extending between the conductive fence and an upper surface of the dielectric substrate. <EOS>