High-speed adaptive RF phased array

We demonstrate dynamic power maximization and synchronization of a wireless RF communication link through adaptation of the radiation pattern of a phased array at the transmitter. Adaptation is performed through a multi-dithering, coherent detection gradient descent analog controller chip, and compensates for phase variations in the communication link. The chip, located at the transmitter, controls the phase of each element in the array so that all transmitted signals combine coherently in phase at the receiver. The control objective is the downconverted RF signal at the receiver, which is fed back to the input of the chip through a reverse, lower bandwidth analog RF link. Measurements on the demonstrated prototype, consisting of a 4-element phased array at the transmitter and an omnidirectional receiver, indicate microsecond scale continuous-time optimization of the system.