Working for Elena Saenz of ESA's technical staff, Roger Appleby and Richard Wylde have installed a mm-wave Scatterometer in clean-room facilities in ESTEC in Holland. Designed to measure scattering from both metalic and dielectric materials down to very low levels, the instrument will cover frequencies from W-band to 750 GHz. An Agilent VNA and VDI heads are used to measuring scattered power, with both the incidence and reflected angles determed by precision optics driven by stepping motors.
Details can be found in this paper presented to the 2017 ESA Antenna workshop
The VNA heads can bee seen on the right, and the sample sits on a holder on the bottom left, with a dual mirror rotating periscope connecting the bottom Tx optics to the top Rx optics. Polarizing wired grids allow the incident E-vector state to be changed from verical to horizontal ( ie S & P) polarization.