R. Maaskant, M.V. Ivashina, S.J. Wijnholds and K.F. Warnick, "Efficient Prediction of Array Element Patterns Using Physics-Based Expansions and a Single Far-Field Measurement", IEEE Transactions on Antennas and Propagation, V60, no. 8, pp3614-3621, August 2012
abstract: A method is proposed to predict the antenna array beam through employing a relatively small set of physics-based basis functions - called Characteristic Basis Function Patterns (CBFPs) - for modeling the embedded element patterns. The primary CBFP can be measured or extracted from numerical simulations, while additional (secondary) CBFPs are derived from the primary one. Furthermore, each numerically generated CBFP, which is typically simulated/measured for discrete directions only, can in turn be approximated by analytical basis functions with fixed expansion coefficients to evaluate the resulting array pattern at any angle through interpolation. This hierarchical basis reduces the number of unknown expansion coefficients significantly. Accordingly, the CBFP expansion coefficients can be determined through a single far-field measurement of only a few reference sources in the field of view. This is particularly important for multibeam array applications where only a limited number of reference sources are available for predicting the beam shape. Furthermore, this instantaneous beam calibration is fast, i.e. potentially capable to speed up the array calibration by one or two orders of magnitude, which is particularly important if the antenna radiation characteristics are subject to drifts.