Characteristic basis function patterns — A novel expansion method for the fast and accurate prediction of antenna array beams

A novel beam expansion method is proposed for the fast and accurate prediction of antenna radiation patterns. Only a few physics-based entiredomain vector basis functions - called Characteristic Basis Function Patterns (CBFPs) - are employed for modeling each far-field beam. To determine the beam expansion coefficients, it suffices to measure the unknown beam for a few angular directions only, after which the beam shape is modeled over a large angular region through the interpolatory CBFPs. In practical systems where multiple embedded element- or array-beams are correlated to form a covariace matrix, it even suffices to perform a single measurement on multiple independent reference point sources in the antenna´s field of view. This is an important step forward for the fast and accurate calibration of antenna beams, in particular for imaging array systems. An illustrative example is presented on both the procedure for generating the CBFPs and determining their expansion coefficients.