Resistively Loaded Ultra-Thin FSS Absorbers for RF Enhancement of Spacecraft Thermal Blankets

This study reports the use of metal backed frequency selective surface (FSS) absorbers as a means to control the scattering of electromagnetic energy from satellite platforms which are covered with thermal blankets. This is achieved by exploting the similarity of the physical construction of this class of absorber and the dielectric clad foil backed outermost layer of space blankets. Simulated results are presented for five absorber designs which are suitable for mechanical integration into the top surface of amulti-layer insulator (MLI). These were constructed using Polyethylene Terephthalate (PET) material with sheet thickness in the range 140 µm (λ=213) − 1120 µm (λ=25). The optimum performance around 10 GHz was obtained from an array of hexagonalpatch elements with the conductivity of the silver plating adjusted to achieve the desired resistive loading. At normal incidence the FSS based structures exhibits −10 dB reflectivity bandwidths that are strongly dependent on the thickness of the PET sheet and vary between 2% and 16%. The design methodology is verified by measuring the radar backscatter from 140 µm and 1120 µm thick absorbers in the frequency range 8 − 12 GHz.