Suppression of Antenna Backscatter on a Nanosat Using a Resistively Loaded FSS Absorber

Abstract

A very thin microwave absorber that can be integrated into the outermost layer of thermal blankets is proposed as a means to electromagnetically decouple payload antennas from spacecraft platforms. The effectiveness of this concept is evaluated for a critical test case where a linearly polarized dipole antenna working at 10 GHz is placed at three different distances above the surface of a $\text{10 cm}$ Nanosat mock-up. This scenario is chosen as the dipole will radiate into both half spaces and any reflections from the vehicle onto which it is mounted will significantly affect its behavior. A resistively loaded frequency selective surface (FSS) absorber is employed to supress the energy contained in the antenna backlobes, and it is shown that the installed performance for all three geometries closely resembles the beam shape of the antenna in isolation. Experimental results have been obtained for one arrangement to confirm that the directive gain is increased by 18 dB in the boresight direction. The FSS absorber is composed of an array of resistively loaded hexagonal patches that are patterned on a 1.12 mm ( $\lambda /25$ ) thick foil-backed polyethylene terephthalate sheet to replicate the physical construction of commercially available space blankets.