Tenders Are Invited For Sub-Mm Wave Noise Sources For Internal Calibration Sub-Systems

Tenders are invited for Sub-Mm Wave Noise Sources for Internal Calibration Sub-Systems - Expro+ Objective: To evaluate the capability of heterojunction bipolar transistor (HBT) technology (such SiGe as and/or InP) as an internal calibrator noise source at sub-mm wave frequencies and manufacture a heterojunction bipolar transistors (HBT) based noise sources at two selected frequencies such as 325 GHz and 448 GHz.Description: Microwave radiometer calibration routine onboard a satellite is currently based on the measurement of external well known reference targets such as cold sky and onboard blackbody target. However, external calibration implies complex moving mechanics and long calibration cycles which are non-optimum from system performance perspective and therefore set certain limitations to instrument performance. Considerable improvements in smaller fluctuation of noise power density are foreseen by complementing or replacing the mechanically switched quasi-optical external calibration systems by internal calibration sub-systems (ICSS) based on electrically switched active semiconductor devices. Semiconductor based noise sources (cold or hot) are key blocks in these ICSS units which will benefit developments of future EO sounders and imagers on small platforms and cube-sats as well as multipixel imagers on bigger platforms. ICSS concept based active cold-loads have already been adopted in Copernicus Imaging Radiometer (CIMR). At higher mm-wave frequencies, hot load -based ICSSs are currently being developed for applications at 89 GHz and 183 GHz based on noise diodes and between 200-250 GHz based on HBTs. Development of a HEMT-based noise source is ongoing at 325 GHz. This activity aims to manufacture a breadboard of a noise source waveguide modules based on HBT technology (e.g. SiGe/InP/GaAs) at two selected sub-mm frequencies of interest for future EO instruments, such as 325 GHz and 448 GHz. The stability of the HBT-based noise sources will be compared with counterparts built on different technologies by means of theoretical assessment and experimental results where available. The HEMT technology provides advantage having the highest frequency capability as anoise source due to its high transition frequency which is already in 1 THz region. However, the anticipated advantage of HBT in comparison to HEMT is its inherently smaller fluctuation of noise power density - a key parameter for a calibrator. The recent developments in HBT technologies (both SiGe and InP) and their frequency capability open possibilities to implementation of a HBT noise source up to sub-mm region which would be a very desirable component for a stable ICSSs. This activity encompasses the following tasks:- Noise source requirements definition from system level - Preliminary to critical design of a noise source waveguide modules basedon HBT technology at two selected sub-mm frequencies such as 325 GHz and 448 GHz - Manufacturing and characterization of the breadboardDeliverables: Breadboard, Report Read less Tender Link : https://esastar-publication-ext.sso.esa.int/ESATenderActions/filter/open