The DTU-ESA Spherical Near-Field Antenna Test Facility, shown in Figure 1, is operated in cooperation between the Technical University of Denmark (DTU) and the European Space Agency (ESA). At the DTU-ESA Facility very accurate measurements and calibrations of antennas are carried out in the frequency range from 0.5 GHz to 40 GHz.
The theory behind this special measurement technique – spherical near-field antenna measurement – was developed at DTU in the 1970’s and the DTU-ESA Facility was established with support from ESA in the 1980’s. Today the Antenna and Electromagnetics Group (AEG) at the Department of Electrical Engineering at DTU operate the DTU-ESA Facility in cooperation with ESA. The DTU-ESA Facility functions as an external reference laboratory for ESA by conducting antenna measurements and calibrations - primarily for Danish and European industry and institutions involved in ESA-projects.
Antenna measurements have been a significant area of research of the AEG for many years and today the DTU is a European stronghold for accurate and advanced antenna measurements. One example of this activity is the participation in the on-going ESA's SMOS project, in which the on-ground calibration for the antenna patterns of the 69 antenna/receiver units of the MIRAS space radiometer was undertaken the DTU-ESA Facility; a calibration that required an unprecedented measurement accuracy of 0.05dB for amplitude and 0.33deg. for phase in a ±35deg. field of view.
Another example is the participation of DTU in the EU network of excellence called ACE - Antenna Centre of Excellence, where DTU is leader of the antenna measurement activities. In recent years, the research in antenna measurements at AEG has focused on high-accuracy antenna measurements, antenna measurement facility comparisons, higher-order probe correction techniques, and antenna diagnostics.
Figure 1. Calibration of the central part of MIROS radiometer at the
DTU-ESA Spherical Near-Field Antenna Test Facility (single-probe antenna test facility).