Algorithm for Transforming Antenna Electromagnetic Near-Field Measured on Spherical Surface into Far-Field Based on Direct Calculation of Stratton and Chu Formulas

This study examines the possibility of direct calculation of vector forms of Kirchhoff’s integral in algorithms of electromagnetic near-field to far-field transformation of antenna harmonic radiation. A simple algorithm based on the integral derived from the Stratton and Chu formulas is proposed for the spherical scanning scheme of electromagnetic near-field. Method errors of the proposed algorithm stipulated by the assumptions made in the process of its derivation are investigated by mathematical simulation. The total error is estimated in experiments on reconstruction of antenna amplitude radiation patterns. For comparison, the results of the classical algorithm performance based on electric field expansion in terms of spherical modes are presented in all experiments. It has been shown that the accuracy of the proposed algorithm in comparison with the classical algorithm is not inferior, the programming complexity is lower, while the execution speed is higher on condition of the reconstruction of radiation pattern only in principal sections.