A scalable wireless power transmission system and its target tracking beaming using a direction of arrival estimator

An active 5.8 GHz wireless power transmission (WPT) system based on scalable transmission and reception modules is developed. The transmitter is a planar active phased array system powered by gallium-nitride class-F power amplifiers and consists of 24 microwave power transfer (MPT) modules integrated with a subarray antenna. Each of the MPT modules can work alone as well as be driven with other modules and also be expanded further. The power receiving system comprises 128 rectenna modules whose DC outputs are combined in parallel. The placement can be modified or extended more to correspond to the width and shape of the incoming beam. A hardware configuration for a concise direction of arrival (DOA) estimation system, composed of a multi-channel switch, a phase modulator, and a power combiner, is also proposed. The azimuth and elevation direction are derived from the method of element electric-field vector by measuring only the amplitudes of a combined field vector. The proposed DOA estimation system and a pilot signal transmitter of 2.45 GHz were installed on the WPT system, and an experiment tracking a target 50 m away was conducted. It could be visually confirmed that the real-time tracking transmission operates properly while maintaining a pencil beam of 1.8 ° width.