We are currently making for EuMETSAT's MetOP-SG MWS and ICI's warm calibration targets. Below is the image of
the MWS On Board Calibration Target (OBCT) Engineerng Qualification Model (EQM)
.... with remarkable S11 coherent reflectivity .... measured by our colleague Axel Murk in the IAP in Bern.
The operational MWS band are greyed out... and we have achieved better than -55dB across all bands.
....full details of the FM2 target's performance can be seen here
and undergoing TVAC cycling and PRT calibration in our facilities in Billingshurst
MWS is part of an ESA funded programme, with TK's customer being AIRBUS in the UK. The views expressed herein in no way be taken to reflect the opinion of the European Space Agency.
There are more details here:
Arne Schröder et al.: Electromagnetic Design of Calibration Targets for MetOp-SG Microwave Instruments, IEEE Transactions on Terahertz Science and Technology, vol.: 7, no.: 6, pp.: 677 - 685, 2017, http://dx.doi.org/10.1109/TTHZ.2017.2757442
Under contract to ESTEC and with partners the then AEA Technology PLC, Thomas Keating developed a decade ago a Calibrated Hot Load (CHL) for the 400 to 1100 GHz region. The aim was to provide the temperature references in future THz space missions requiring accurate radiometric calibration.
We have been continuing this work over the last 10 years or so. A conference paper presended by Axel Murk at IGARSS in 2012 shows our approach. A related paper present at CPEM in Washington covers standing wave issues in more detail.
This interest in the design and manufacture of Radiometer Targets has lead us to make the ALMA Telescope Targets (now available for purchase) as well as current MetOP-SG MWS and ICI targets.
Recent work for David Walker and Derek Houtz at NIST in Boulder has included the design and manufacture of two cone calibration standards which, inter alia, will be used to calibrate Northrop Grumman's ATMS instruments. There are also, we understand, discussions underway about using these
The liguid/gas nitrogen cooling piped are fully electroformed into the holding structure, and give surprisingly good thermal conductivity. The image below was taken prior to final Cu deposition.
and built into a thermally insulating structures
The larger version is seen above, the smaller one below
and more details here
Derek. A. Houtz et al.: Electromagnetic Design and Performance of a Conical Microwave Blackbody Target for Radiometer Calibration, IEEE Transactions on Geoscience and Remote Sensing, vol.: 55, no.: 8, pp.: 4586 - 4596, 2017, http://dx.doi.org/10.1109/TGRS.2017.2694319
We have also made a small calibrations cone for JPL .... as seen below. The "L" shaped struture with black paint on the bend reduces the IR radiation load on the microwave-absorbing inner part of cone.
Two Goodridge PRT's are potted into the cone structure
....have been carefully soldered to readout wiring under clean conditions:
Details of the cone and the ANSYS Non-Linear Thermal analysis are set out here
TK is also working on an even smaller target for the Microwave Radiometer on ESA's JUICE mission for our colleague Axel Murk at the IAP in Bern.
Image below show the cone - which has to survive intensive ionising radiation levels near Jupiter- underging vibration tests (Image thanks to the IAP).
See Karl Jacob, Arne Schröder, Axel Murk: Design, Manufacturing, and Characterization of Conical Blackbody Targets With Optimized Profile, IEEE Transactions on Terahertz Science and Technology, vol.: 8, no.: 1, pp.: 76-84, 2018, http://dx.doi.org/10.1109/JSTARS.2019.2913729
The CHL and it derivitives were scaleless designs based upon a tapered cone lined with microwave absorber. They survive vibrational and thermal vacuum cycling to generate a fully space qualified designs.
To the left you see a side view of the cone, with power and PRT sensor cable clearly visible.
On the right, the cone itself.
and here is a side view.
Axel Murk has also measured the monostatic performance of the CHL at 400 GHz