Study stopped at after PDR.
On the FSS preliminary design on quartz technology, it is not considered relevant to continue with further analysis (specification not reached).
Considering the RF results on Kevlar samples, the QUB feedback and the poor thermal capability, it is not considered relevant to continue with further activity.
Kevlar is lossy and with an effective permittivity >1. Both are a major drawback mainly at Ka band.
Above 16GHz it becomes impossible to have identical response for TE/TM. The operation in linear polarization would be simpler, but the insertion losses would remain. It is not possible to compensate by design the difference in Amplitude and Phase over a wide bandwidth (phase is constraining and sensitive). Therefore, the Axial Ratio becomes very bad and only usable on a small band (target ~0.5dB for few hundred of MHz).
For a Ku Ka FSS, a less lossy glue/material and thicker metallisation is needed.
The exact knowledge of the permittivity of each layer of the sandwich (skin, honeycomb, adhesive for the required frequency) and their exact size/thickness is major and key to designing an FSS.The RF behaviour of the honeycomb (with a detailed description) is also a big challenge at SW/HW levels.