Some devices designed to simulate or characterize the scenario from a radar point of view need to use the widest possible band (even tens of GHz) in the microwave range.
This very wide operating band is then scanned using signals that have a more limited instantaneous bandwidth.
For simplicity and technological limitations, the original signal, with all its spectral components, is generated at lower frequencies and then relocated to higher frequencies via the up-conversion modules, thus covering very extensive operating frequency ranges.
The difficulty of this project was due to very restrictive specifications on amplitude flatness and phase linearity to be respected across the entire band, as well as having to work with components up to a frequency of 40GHz.
Furthermore, the definition of the architecture and the preliminary analysis had to pay particular attention to stringent limitations on the spurious conversion frequencies, typical of these systems.
The up-conversion module was finally housed inside a rack unit.