▎ 摘　　要

This paper presents the design and simulation of two distinct reflection-mode graphene cross-polarization converters (CPCs), which operate in the THz region. The first is a tri-band converter capable of converting linear and circular to cross-polarized waves at 6.0, 9.0, and 13.3 THz, with a polarization converter ratio (PCR) greater than 0.98. Also it converts linear to circular-polarized waves at 5.0 and 11.0 THz. The designed converter is stable over incidence angles from 0 degrees to 60 degrees, with a slight degradation in bandwidth near 60 degrees. The second is an ultra-wideband (3.75 to 11.35 THz) linear to cross- and circular to cross-polarization converter with a PCR ratio of 0.85. The bandwidth of the second converter has been enhanced by using the same structure as the first, but with dual-layered graphene. Furthermore, the proposed structures can be dynamically tuned by varying the chemical energy of the graphene, without needing to modify the physical geometry. (C) 2020 Elsevier B.V. All rights reserved.