Specialized radio-frequency coils and sensors placed inside a magnetic resonance imaging (MRI) scanner considerably extend its functionality. However, since cable-connected in-bore devices have several disadvantages compared to the wireless ones, the latter are currently under active development. One of the promising concepts in wireless MRI coils is energy harvesting, which relies on converting the energy carried by the radio-frequency MRI field without the need for additional transmitters, similar to common wireless power-transfer solutions. In this paper, we propose a compact harvesting coil design based on the combination of loop and butterfly coils that allows energy harvesting of a circularly polarized field. By performing numerical simulations and experiments with commonly used Siemens Espree and Avanto tesla MRI scanners, we demonstrate that the proposed approach is safe, efficient, does not decrease the quality of MRI images, and allows doubling the harvested voltage compared to the setups with linearly polarized fields.