A.V. Kirpanev, V.S. Nasarov, Yu.G. Shatrakov, V.V. Shubnikov

A spherical scan in antenna testing is the measurements of the field components on a spherical surface that surrounds test antenna. Subsequently measurement data make it possible to determine far field (determining antenna pattern), near field (electromagnetic compatibility testing) and aperture field or antenna array element field (wave diagnostics). It often exists a need to determine antenna radiation characteristics in antenna-object system. In this case, the estimated phase center of antenna as a rule is considerably displaced about the center of measuring sphere of scanner. For study of how such measuring conducts influence on result the mathematical model of standard radiation source has been developed. In this model a field of radiation source on surrounding sphere was calculated for different position of phase center about center of measuring sphere. Based on the results of computational investigation the required number of spherical wave harmonics is ascertained. It is shown the influence of instrumental and method errors on result of determining antenna pattern in far field. Peculiarities of methods for eliminating influence of secondary field on basis of ultrabroadband measurements are discussed.