A device for harvesting radio frequency (RF) energy to generate power includes a first spiral antenna having a first spiral direction, the first spiral antenna having a spiral cross-section shape along a first flat plane. The device includes a second spiral antenna having a second spiral direction opposite the first spiral direction, the second spiral antenna having a spiral cross-section shape along a second plane parallel to the first plane. The device further includes a ground layer between the first and second spiral antennae, the first spiral antenna electrically connected to the second spiral antenna at a center of the first and second spiral antennae by a conductive element passing through the ground layer without contacting the ground layer.