Session
Science/Mission Payloads
Location
Salt Palace Convention Center, Salt Lake City, UT
Abstract
The Copernicus Microwave Imaging Radiometer (CIMR) employs a 7.1 m conical scanning mesh reflector antenna rotating at 7.8 rpm that operates from L to Ka band. Demanding radiometric accuracies and sensitivities at few tenths of a Kelvin at high spatial resolution are targeted for the instrument. These require a high accuracy in the characterization and modelling of the antenna pattern over 4π, considering any nearby scattering structure, and/or any potential multipath due to the antenna installation on the S/C, as well as the quantification of the uncertainty on the beam efficiency (BE) arising (from possible in-orbit random variations in the reflector surface and in the reflectivity of the mesh. For these reasons, a platform scattering analysis of the reflector antenna on the CIMR satellite was undertaken for a subset of feeds at L, C, X, K, and Ka bands. By adding a scatterer at a time and performing a full wave analysis at all frequency bands, the scatterers that mostly affect the RF performances were found. It was shown that the boom, truss and S/C with solar panels have a negligible impact on the BE variation while the crate is the scatterer which gives the highest contribution. In addition, it was shown that the crate doesn’t behave in the same way for the two orthogonal polarizations. In addition, an uncertainty quantification (UQ) analysis was carried out on the position of the nodes of the tensioning net generating the reflector surface, and on the reflectivity of the reflective mesh over the frequency bands of interest. It was found that the impact of varying the reflector surface is greatest for the highest frequencies used by the CIMR instrument, and that the surface deformations have a larger impact on the RF performance than the changes in the reflectivity of the mesh.
Document Type
Event
Uncertainty Quantification and Platform Scattering for the CIMR Reflector Antenna
Salt Palace Convention Center, Salt Lake City, UT
The Copernicus Microwave Imaging Radiometer (CIMR) employs a 7.1 m conical scanning mesh reflector antenna rotating at 7.8 rpm that operates from L to Ka band. Demanding radiometric accuracies and sensitivities at few tenths of a Kelvin at high spatial resolution are targeted for the instrument. These require a high accuracy in the characterization and modelling of the antenna pattern over 4π, considering any nearby scattering structure, and/or any potential multipath due to the antenna installation on the S/C, as well as the quantification of the uncertainty on the beam efficiency (BE) arising (from possible in-orbit random variations in the reflector surface and in the reflectivity of the mesh. For these reasons, a platform scattering analysis of the reflector antenna on the CIMR satellite was undertaken for a subset of feeds at L, C, X, K, and Ka bands. By adding a scatterer at a time and performing a full wave analysis at all frequency bands, the scatterers that mostly affect the RF performances were found. It was shown that the boom, truss and S/C with solar panels have a negligible impact on the BE variation while the crate is the scatterer which gives the highest contribution. In addition, it was shown that the crate doesn’t behave in the same way for the two orthogonal polarizations. In addition, an uncertainty quantification (UQ) analysis was carried out on the position of the nodes of the tensioning net generating the reflector surface, and on the reflectivity of the reflective mesh over the frequency bands of interest. It was found that the impact of varying the reflector surface is greatest for the highest frequencies used by the CIMR instrument, and that the surface deformations have a larger impact on the RF performance than the changes in the reflectivity of the mesh.
