Extension of the Technical University of Denmark (TUD)-ESA spherical near-field facility to the 20/30 GHz bands

Two waveguide systems for dual polarization measurements at 20 and 30 GHz, respectively were constructed. The RF-system; modifications of the receiver, the control hardware and the software; and problems detected during measurements with the system are discussed. The verification measurements comprise measurements on 2 standard gain horns, 2 conical horns, and a 7 horn feed array manufactured as a part of a 20/30 GHz multibeam antenna. Measurements with the 20 GHz system and the 30 GHz system are described. The facility can be used for single polarization measurements (i.e., standard gain horn calibrations) at all frequencies between 18 and 40 GHz, while dual-polarization measurements were implemented in the bands 18.9 to 19.9 GHz, and 27.4 to 30.3 GHz. However, the only components missing for carrying out dual polarization measurements outside these bands are OTM's and conical horn probes.