A broadcast reference technique for self-calibrating of large antenna phased arrays

A modified phase-multilateration technique is proposed for calibrating the element locations of a flexible phased array. The technique requires several auxiliary beacons. The calibrating system measures the phase, relative to a broadcast reference, of each beacon signal at each array element. Automatic calibration of the differential phase delay in each antenna element signal path is included in the self-survey process. Digital beamforming is used for array signal processing. The beacon locations can be accurately or loosely known. For the system with loosely known beacon locations, an additional baseline measurement is required, and the beacon locations are treated as unknown variables. It is shown that a simple variable transformation can transform the mathematical equations of this technique into a form identical to that of the corresponding equations of previous cabled reference systems. The mathematical properties of the algorithm and its associated tolerance analysis are therefore readily available. A combination of the versions of this technique with accurately known and loosely known beacon locations is shown to have better performance than the individual version