Joint calibration of mutual coupling and channel gain/phase inconsistency using a near-field auxiliary source
A new indoor calibration method is proposed to estimate and compensate mutual coupling and channel gain/phase inconsistency parameters for a uniform linear array (ULA). This calibration method employs only one assistant source in near-field and is unnecessary to conduct complex feed circuits behind the antennas. Firstly, accurate channel gain/phase deviation is estimated via an inside testing structure exploiting the coherence of a single-frequency test signal. Then, the received array manifold of the near-field auxiliary source is modeled with a second-order Taylor series approximate. Finally, joint mutual coupling and gain/phase error are compensated using the inside testing results and modeled array manifold as the initialization of the eigenstructure (also called subspace) technique, which profoundly accelerates the convergence and guarantees the uniqueness of the converged solution. Experiments conducted on an actual 16-element ULA validate the proposed method.