Advanced spherical near-field antenna measurement techniques - recent research and ESoA PhD course

The DTU-ESA facility has since the 1980es provided highly accurate antenna radiation pattern measurements and gain calibration by use of the probe corrected spherical nearfield technique, both for ESA (the European Space Agency) and other customers and continues to do so. Recent years activities and research carried out at the facility are presented in the article. Since 2004 several antenna test facility comparison campaigns were carried out between a number of European antenna measurement facilities. The first campaigns laid the foundation for the later comparisons in providing experience and showing the capabilities of each participating facility. A special campaign was carried out with the aim of establishing a reference radiation pattern for the DTU-ESA VAST-12 antenna. The on-ground calibration of the MIRAS space radiometer for ESA´s SMOS mission was carried out at the DTU-ESA facility in the period 2005-2006 following a series of investigatory measurements and facility updates during 2003-2005. Antenna diagnostics by a SWE-to-PWE transformation presents a case where highly accurate antenna measurements and a plane wave back-projection enable antenna diagnostics by examination of the nearfield close to the antenna surface. The research on antenna measurement techniques is continued with the development of a higher-order probe correction algorithm for spherical near-field antenna measurements which allows the utilization of a wider range of probe antennas.