Measurements of ADMIRALS RTO at 650 GHz in a Hologram-Based Compact Antenna Test Range
See Compact antenna test ranges web page for the structure of the hologram and experimental set-up.
Introduction
Within a European Space Agency project, tests of a 1.5-m diameter reflector antenna were carried out at 650 GHz in the autumn 2006. The test antenna was ADMIRALS Representative Test Object (RTO) constructed by EADS Astrium.
Hologram CATR
Figure 1. Artistic view of the 650 GHz hologram CATR.
Figure 2. Photograph of the hologram for 650 GHz antenna tests.
Instrumentation
- Scaffoldings and polypropylene mats were used to construct the absorber walls
- Modified gun-pedestal was used as the antenna rotator
- Plane-polar scanner with a 2.5-m arm was used in the quiet-zone field verification
- Use of the AB Millimetre MVNA-8-350 vector network analyzer enabled phase measurements
- Dynamic range was 27 dB in the quiet-zone tests and 74 dB in the antenna measurements
- Pilot-signal-based phase correction system was used to correct the phase errors due to the bending cables
Hologram
- Diameter of the hologram pattern was 3.16 m
- Three hologram pieces were joined by soldering
- Electrically invisible and mechanically strong seam
- About 4000 solder connections in each seam
Figure 3. Example of the hologram structure and a soldered seam.
Results
- Amplitude deviation in the quiet-zone was 3.0 dB peak-to-peak; typical ripple was 1.5 dB
- Influence of the measured quiet-zone field was numerically removed from the antenna radiation pattern