A Microwave Power Transmission Experiment Based on the Near-Field Focused Transmitter

For most microwave power transmission (MPT) applications, the microwave power is received within the near field of a large-scale transmitting antenna from a limited distance. This letter explores the design of a near-field focused transmitting antenna to concentrate the microwave power on the receiving antenna's aperture, and thereby to enhance the transmission efficiency of the MPT. A near-field planar array with a size of 1 m × 1 m working at 5.8 GHz is manufactured. To focus the microwave power at a distance of 10 m, its 8 × 8 radiation elements are fed with an equal amplitude but different phase using coaxial cables of different lengths. An MPT experiment is conducted. The measurement shows that, compared with a traditional equal-phase array, the near-field focused array obtains a much more concentrated microwave beam. The transmission efficiency is significantly increased from 32.98% to 41.85%.