Resistively Loaded FSS for Suppressing Antenna Backscatter on Spacecraft Platforms

This paper reports on a simple, cost-effective and novel approach for electromagnetically decoupling antennas from spacecraft platforms. This is achieved by deploying a very thin metal backed resistively loaded Frequency Selective Surface (FSS) to suppress the scattering of linear polarised (LP) or circularly polarised (CP) waves from the metal structure. The microwave absorber is similar in construction as commercial available multi- layer insulator (MLI) material and therefore can easily be integrated into the top surface to provide enhanced radio frequency (RF) performance in conjunction with thermal control and protection of the payload instruments. Full wave electromagnetic simulations are used to demonstrate the effectiveness of this concept by modelling the radiation pattern of a CP dipole antenna which was designed to work at 10 GHz and is placed a distance of λ/2 above the metal surface of a 10 cm3 CubeSat. This arrangement represents the worst-case scenario where destructive interference produces a null on boresight and crosspolar levels which are higher than the reference polarisation. However, the numerical results show that the shape of the undistorted radiation pattern of the antenna in isolation is almost fully restored in the forward hemisphere when the surface of the CubeSat is covered with a 2D periodic array of resistively loaded hexagonal patches which are printed on a 1.12 mm (lambda/25) thick film of Polyethylene Terephthalate (PET).