Mutual Coupling Calibration using Decomposed Coupling Matrix Model

Mutual-coupling-based calibration methods are an attractive means of calibrating digital array radars (DARs) as they alleviate the requirement of far-field sources and/or additional hardware for near-field calibration. Current mutual coupling calibration techniques leverage regular array structure (e.g., uniform planar or uniform linear arrays) with the infinite array assumption, which may result in degraded estimates when this assumption weakens. In this work, this assumption is generalized through incorporation of prior knowledge of the array scattering matrix during the estimation of the transmit and receive gain and phase errors. The assumed scattering matrix is decomposed into a scattering matrix that follows the infinite array assumption, and two other scattering matrices that encapsulate the deviation from ideal which are integrated into the estimation routines. Using the CEM model of an <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$M=16$</tex> element uniform linear array, a Monte Carlo analysis is performed which demonstrates the utility of the approach in calibrating arrays that may not conform to an idealized structure, as compared to existing calibration algorithms.