Joint estimation of gain/phase mismatches and I/Q imbalances in array antenna subsystems

A novel technique is presented in this paper to estimate impairments of array antenna subsystems induced by analog/RF circuits, which include gain/phase mismatches among different antenna elements and imbalances between in-phase and quadrature (I/Q) branches of each element. These impairments are formulated as an impairment parameter matrix (IPM), which can be estimated by using a noise subspace fitting method with known directions-of-arrival (DOAs). An iterative algorithm is developed to estimate the IPM without prior knowledge of DOAs. Carmer-Rao lower bound (CRLB) is derived as a performance measure for the estimation technique.