Phase and time switching modulations for multi-point wireless power grid to realize stable power reception under rotational misalignment

Polarization and antenna pattern misalignment between transmitting and receiving antennas will reduce received power in wireless power transfer. In 2D case, two transmitting and one receiving dipole antennas are at same plane. When rotating receiving antenna, received power will change due to antenna pattern misalignment. 90° phase different between two orthogonal transmitting antennas can realize stable reception for receiving antenna in all rotation angles at a 2D plane. But this technique can not be used in 3D case. Time switching among transmitting antennas can achieve stable reception in all rotation angles in both 2D and 3D cases. The efficiency in 2D case is 1/2, and 1/3 in 3D case. Experiment results using RFID show stable reception at different rotation angles and good agreement with theoretical prediction on efficiency in both 2D and 3D cases.