Reconfigurable folded reflectarray based on an active 1-bit metasurface and its application in microwave hyperthermia

An electronically reconfigurable folded reflectarray (ERFR) is developed. The proposed ERFR comprises an electronically reconfigurable polarization-conversion metasurface (ERPCM), a polarization-selective metasurface (PSM), and a feeding antenna. The PSM that is placed over the ERPCM is employed to reduce the profile of the ERFR, and the feeding antenna is located at the center of the ERPCM. Additionally, by electrically controlling the phase compensation distribution situation at the ERPCM, the ERFR can collect the electromagnetic waves radiated from the feeding antenna at desired positions, which enables the real-time control of the focal spot of ERFR. This provides unprecedented potential for applications in microwave hyperthermia. To demonstrate such potential, the proposed ERFR is used to heat large-sized, irregular-shaped superficial tumors. The simulations and experimental results show that the designed ERFR can heat the whole tumor to therapeutic temperature (over 40 °C) by dividing the tumor into several sub-regions that match the focal spot size and moving the focal spot across the tumor to heat these sub-regions individually.