Design, build and test of a Transmit/Receive-module unit in GaN technology for next generation of C-band SAR based on given requirements.

 

 

Next generation of C-band SAR utilising Digital Beam Forming (DBF) techniques allow significant coverage improvements at high resolution as confirmed in several ESA studies in the field. Several TRP studies in the field of Digital Beam Forming (DBF) have confirmed the feasibility to achieve 400km swath width at 5m x 5m resolution, while Sentinel-1 achieves currently 80km at 5m x 5m resolution. The DBF technological elements are currently under development in the GSTP activity ?Integrated Tile Demonstrator (ITD)? based on extended Sentinel 1 requirements. Within Phase 1 of the activity a partial tile, a recurrent part of the full antenna, is under specification and design. The preliminary specification for the Transmit/ Receive Modules (TRM) has identified high peak power requirements of 50Watts which calls for advanced GaN technology in order to achieve this peak power at high efficiency.

GaN technology has progressed very well. Relevant European 0.25um GaN technology under space evaluation achieved approval in 2014. The proposed GSTP activity will significantly benefit from the TRP activity "Single Chip C-band LNA/HPA in GaN technology" in which a key element is developed on Breadboard level to achieve TRL 3.

 

Existing TRM technology needs to be improved in view of the challenges related to the high peak power and related high voltages, which otherwise will result in destructive discharge effects (corona and multipactor). Current technology supports power levels up to 20 Watts for which discharge effects are already critical.

 

Furthermore the next generation C-band SAR instruments will introduce advanced instrument calibration techniques allowing calibration while imaging. This results in new challenges for TRMs because very high internal signal isolation is required. Within the activity the next generation of TRMs utilising advanced GaN technology shall be designed, built and tested based on requirements as derived in the activity Integrated Tile Demonstrator (ITD). The TRM shall be tested in thermally representative environment.

 

Robustness against discharge effects shall be demonstrated by test.