Pre-development of Critical Technology for the MetOp-SG Microwave Sounder (MWS) Instrument

Lead Organisation: Astrium Ltd

Partners: STFC Rutherford Appleton Laboratory (RAL) & Thomas Keating Ltd.

This project will undertake the development of a 165/183GHz waveguide diplexer, which has the potential to greatly reduce the complexity of the Quasi-Optical Network (QON) for the MetOp-SG Microwave Sounder (MWS) instrument. The 165 GHz channel must be separated from the 183 GHz channels in order to allow these to use separate mm-wave receivers since it is not possible for a single receiver to cover the full bandwidth. The separation of the channels can, in principle, be performed quasi-optically using a dichroic beam splitter but the resultant QON would be complex. An alternative approach is to use a common QON path for both sets of channels and then perform the separation within a waveguide diplexer. The diplexer will consist of a Y-junction with suitable cavity waveguide filters in the 2 output arms. The main requirement will be to achieve low insertion loss (< 1 dB) between 164 – 167 GHz and between 175 – 191 GHz. Since the diameter of the waveguide will be ~1mm, manufacture of the diplexer will only be possible by electroforming. Three identical waveguide diplexers will be manufactured and tested to verify that both the required mechanical tolerances of <5μm and the insertion loss performance over the required 165 and 183 GHz MWS channels have been achieved. The development will not only enable the UK to prepare for the Phase B MWS instrument opportunity by addressing a key instrument technical issue not covered by the ESA Phase A and parallel technology development studies but also has potential application to other instruments operating in the 100 GHz to 200 GHz frequency range.

The project lead is Astrium Ltd, supported by STFC Rutherford Appleton Laboratory (RAL) and Thomas Keating Ltd