In this PoC project, silicon-micromachined high-Q filter technology was investigated for radiometer applications, which enables a new generation of radiometers combining: 1) high spectral resolution, enabled by the micromachined high-Q narrow-band filters; 2) best-possible signal to noise ratio achieving high sensitivity, since direct-receivers can be utilized; 3) single detector front-end, allowing uniform performance for multiple bands as compared to multi-detector architectures, enabled by the micromachined waveguide switches; 4) very compact, low-weight radiometer since no superconducting elements (requiring cryogenic cooling systems) required. The project has resulted in several ground-breaking results, including the world's first 1% fractional bandwidth filter at submillimeter-wave frequencies (i.e. above 300 GHz), a filter demonstrator demonstrating a Q factors of 950 at 700 GHz, achieving the best insertion loss and quality factors ever reported in this frequency range up to date. The project furthermore investigated in-plane waveguide filter geometries with co-axial port arrangement, which enables stacking of filters and thus filter banks. The project has resulted in a spin-off company, which now has received its first funding round and has three full-time employees. Furthermore, the project has resulted in a follow-up research project with the European Space Agency (ESA), where the technology will be utilized for reconfigurable radiometers for future weather satellites, which was proposed in the project proposal as the main application scenario.
