Analysis and Measurement of Reflector Antennas in the MM-Wave Frequency Range

For the ADMIRALS study of ESA/ESTEC, performed in 2000 - 2002 and subsequent mm-wave studies in 2003 - 2005, a Representative Test Object (RTO) was designed and built to validate the antenna measurement performance with a high gain reflector antenna at 203, 322 and 503 GHz. The RTO mainly contains out of an offset reflector antenna with 1.5 in reflector diameter and is related to future remote sensing antennas as FIRST, MASTER or HERSCHEL/PLANCK. For assessment of measurement results, the RTO was theoretically analyzed with the simulation tool GRASP. For improvement of the simulation model, primary feed and surface contour data of the reflector - measured at the feed as well as reflector manufacturer - were taken into account within the simulations. Within further simulations, reflector deformation effects due to the mounting configuration regarding the reflector backing structure of the RTO reflector could be identified with additional surface measurements of the RTO reflector. Additional optical measurements were performed with a highly accurate laser tracker system and measurement technology. The accuracy of these measurements could be identified with 10 .. 20 mum. This work was finished in 2005 and the results are described in this paper.