RF hardware such as filters under high-power operation requires careful temperature compensation to ensure thermal stability. Existing techniques [1-3] are mostly based on low coefficient-of-thermal-expansion (CTE) invar or external compensation structures and have been used for a very long time. There is a drive to develop new materials and new compensation techniques in order to reduce the reliance on invar or complex assembly.
One main objective of the project is to develop an entirely new temperature-compensation technique using an integrated artificial ‘material’ with engineered properties which do not depend on CTE of the materials or external assembly. On the other hand, it becomes increasingly clear that the topological co-design [4], considering trade-offs between RF, thermal and mechanical performance as well as mass and volume, is critical for high power filters. Currently there is a lack of a systematic approach and a defined framework for RF/microwave engineers to achieve this goal.
The second objective of this project is to develop a practical framework comprising defined drives in the multiple design domains and the related methodology. Both objectives will be enabled by the emerging additive manufacture (AM) technology. AM will allow the realisation of unconventionally-shaped monolithically-built microwave resonators/filters [5,6] as well as some complex lattice structures which offer engineer-able properties [7].
The novelty of the idea lies in two folds:
- a novel temperature compensation mechanism using integrated Auxetic lattice structures with negative Poisson’s ratios;
- a multi-domain topological co-design framework for high-power filters.
The project aims to demonstrate two high-power filters in relevant space applications, one based on optimised resonator geometries incorporating topological thermal and mechanical optimisations and the other based on the novel temperature compensation technique using Auxetic structures.
[1] Marco Lisi, “A Review of Temperature Compensation Techniques for Microwave Resonators and Filters”, Micro Millimetre Wave Tech. Tech. Workshop, ESTEC, Noordwijk, The Netherlands, 2014. https://www.researchgate.net/publication/326902704_A_Review_of_Temperat…
[2] “Maximizing the Potential of Additive Manufacturing with Design Optimization”, https://www.altair.com/pd/customer-story/thales-alenia-space/maximizing…
[3] P. Booth and E. V. Lluch, "Enhancing the Performance of Waveguide Filters Using Additive Manufacturing," Proc. IEEE, 105(4), pp. 613-619, 2017. doi: 10.1109/JPROC.2016.2616494
[4] C. Guo et al., "Shaping and Slotting High-Q Spherical Resonators for Suppression of Higher Order Modes," 2019 IEEE MTT-S International Microwave Symposium (IMS), Boston, MA, USA, 2019, pp. 1205-1208, doi: 10.1109/MWSYM.2019.8700752.
[5] S. Li, H. Hassanin, M. M. Attallah, N. J.E. Adkins, K. Essa, “The development of TiNi-based negative Poisson's ratio structure using selective laser melting,” Acta Materialia, 105, 2016, pp. 75-83. https://doi.org/10.1016/j.actamat.2015.12.01
