Our ESA project COLD (Compact On-board L-band Diplexers for high-power applications), not only researches practical solutions for reducing the mass/footprint of the filter in space applications but also contributes to scientific research.

Just in these days the International Journal of Microwave and Wireless Technologies, a journal of Cambridge University Press’s academic content sponsored by EuMA, published an article by our RF/Microwave project team.

The study presents the work concerned with a European Space Agency (ESA) Advanced Research in Telecommunications Systems (ARTES AT) project called COLD (‘Compact On-board L-band Diplexers for high-power applications’, ESA Contract Number: 4000120093/17/NL/NR). RF Microtech is prime contractor and Thales Alenia Space Italy our partner.

Visit COLD project 


The current state of the art for telecommunication satellite input and output filters at L-band (1-2GHz) consists of bulky networks. Usually these filters are based on standard technologies such as coaxial circular or rectangular waveguide cavities. Such solutions allow for good performance in terms of insertion loss, power-handling, and spurious-free stop-band ranges, but they are bulky and heavy at L-band, thus going against the communication market key drivers where compact and lighter structures are required.


The challenge of reducing the mass/footprint of the filter in space applications
has been a very hot topic since last decades, for this reason the effort in the design of compact microwave filters (mainly below 5 GHz) has been notably increased.
In this scenario, filters at L-band based on high-permittivity ceramic materials allow for an important volume reduction without compromise the RF performance.




The publication describes the design and first experimental results of Tx and Rx L-band bandpass filters for a high-power satellite diplexer. Designed in the framework of an ESA ARTES AT project, the filters are based on TM010 mode dielectric resonators.



Dielectric-loaded L-band filters for high-power space applications:

TM010 mode dielectric resonators allow for better results in terms of volume occupation with respect to other dielectric resonators still maintaining high Q-factor values (>2000). Volume saving above 30% is achieved with respect to standard coaxial filters. The filter geometries and materials have been chosen in order to improve the power-handling and to cope with related critical issues for space applications (i.e. avoid any multipactor discharge in the operating RF power range and to have a low-PIM response). Measurements of filters show good correlation with the design in terms of central frequency and unloaded Q-factor (around 3000).
Multiple analyses are ongoing to further improve the results in the final engineering model that will be measured in next months.


Thanks to  RF Microtech team and thanks to our partners Thales Alenia Space Italia, European Space Agency and University of Perugia for their contributions and support.

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You can get access to the FULL VERSION OF PAPER at this link or CONTACT US for more details!


We dedicate this work to the memory of Prof. Roberto Sorrentino.
He was an educator, an innovator, and an excellent microwave expert.
His dedication to work, honesty, and integrity will always be an inspiration for his former students and colleagues toward excellence.