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Hier finden Sie wissenschaftliche Publikationen aus den FraunhoferInstituten. On the Influence of Probe Positioning Errors due to Mechanical Uncertainties in Spherical Nearfield Measurements at Terahertz Frequencies in Modern Positioner Systems
 Institute of Electrical and Electronics Engineers IEEE: PhotonIcs & Electromagnetics Research Symposium  Spring, PIERSSpring 2019. Proceedings : 1720 June 2019, Rome, Italy Piscataway, NJ: IEEE, 2019 ISBN: 9781728134048 ISBN: 9781728134031 S.18831888 
 PhotonIcs & Electromagnetics Research Symposium (PIERSSpring) <41, 2019, Rome> 

 Englisch 
 Konferenzbeitrag 
 Fraunhofer FHR () 
Abstract
Spherical nearfield measurements are regarded as the most accurate technique for the characterization of an Antenna Under Test's (AUT) radiation. The AUT's farfield radiation characteristics can be calculated from the Spherical Mode Coefficients (SMC), or spherical wave coefficients, determined from nearfield data. At Terahertz frequencies, the farfield approximation distance classically defined by the Fraunhofer distance is easily met. Still, the spherical nearfield framework can also be applied to measurements beyond the AUT's near field, providing a reliable way of determining its radiation pattern with any resolution from a relatively coarse measurement. Moreover, the AUT's radiated power can be calculated from the SMC. However, the mechanical uncertainty at these frequencies is comparable to the wavelength, thus introducing basis mismatch between the measured grid and the grid assumed for the transformation into the SMC domain, which results in reconstruction error. In this work, a theoretical stochastic analysis at 0.3 THz is performed. Random superpositions of spherical modes are generated and, for each one, a number of reconstruction experiments affected by a random grid error in line with standard measurement systems is executed. The results for the ideal and the distorted grids are compared and the mean and maximum error are statistically evaluated.