Antenna Reciprocity Calibration Using Reference Antennas

The patent makes the antenna array elements serve multiple functions: they act as both transmit/receive antennas during normal communication operations and as calibration references during calibration procedures. Specifically, antenna elements are used as both the antenna being calibrated and the reference antenna, eliminating the need for separate dedicated calibration transceivers while maintaining calibration accuracy through the reciprocity principle

The antenna array performs its own calibration using its existing elements and operational signals. The system uses its own transmit and receive chains, along with signals already present in the communication environment, to calibrate the antenna elements. This self-calibration approach eliminates external calibration equipment and reduces overall system complexity while maintaining measurement precision

The patent introduces an intermediary reference antenna that serves as a mediator between the antenna being calibrated and the calibration process. This reference antenna, which can be one of the existing array elements, facilitates calibration by providing a stable reference point that can be accessed from both transmit and receive perspectives, thereby simplifying the operational complexity of calibrating antennas in different modes

The patent applies the reciprocity principle, which states that the calibration process can be inverted or reversed. Instead of directly measuring an antenna in one mode and assuming the same characteristics in another mode, the system performs measurements in both transmit and receive directions and uses the reciprocity relationship to derive accurate calibration coefficients. This inversion approach maintains accuracy while simplifying operations by leveraging the symmetry in the system