Impacts of Expectable Large Deployable Reflector Deformations on Digital Beamforming

Abstract:
Upcoming radar missions for Earth observation focus on longer wavelengths in L- or even P-band. Operationally, these instruments will be constructed as an antenna feed array paired with large deployable reflectors (LDR) to achieve highly versatile instruments and high-gain antenna beams at realizable cost. Compared to current planar array based systems, these upcoming missions face a slew of novel challenges. One major concern is the impact of potential LDR distortions at different timescales on receive beams, calculated based on digital beamforming techniques. In this paper, we discuss the impacts of expected LDR surface distortions on maximum beam gain and beam pointing based upon a potential Tandem-L instrument geometry for a legacy LDR with a diameter of 12 m. We find that deployment uncertainties have a notable effect, while inter-orbit thermal distortions may not noticeably influence gain and pointing of the calculated receive beams.