Critical aspects adversely affecting accuracy of radiation pattern and polarization measurements with three spherical scanners at high microwave frequencies

Ability to perform spherical measurements of small to medium size antennas at high microwave frequencies is presented in this paper. The focus is on three scanning system developed in-house by the authors. A key to accuracy of measurements is a careful approach to antenna positioner design and to maintaining geometrical accuracies during probe scanning. The following approaches have been presented: two dual-wheel systems made with different materials and a probe circling setup with the semi-arm. It is shown, how a set of acquired electric field samples on the sphere, can be used for direct determination of antenna radiation efficiency.