Diagnostic and investigation of sub-array radiation of large array antenna by inverse source technique

This paper describes the application of the inversesource also named source-reconstruction technique [1-4] applied to the practical case of a space antenna intended for the European Navigation System GALILEO. The antenna (a pre-development flying on the GALILEO In Orbit Validation Element-B (GIOVE-B) satellite) consists in an array of 42 patch elements, divided into six sectors and fed by a two levels beam forming network (BFN) as described in [5]-[6]. The BFN provides complex excitation coefficients of each array element to obtain the desired iso-flux shaped beam pattern. The measurements have been performed in the new hybrid (Near Field and Compact Range) facility in the ESTEC CPTR as part of the installation and validation procedure [7]. The inverse-source technique has been applied to identify and filter out possible spurious signals presents in the hybrid facility and to isolate the sub-array radiations in order to highlight possible errors.