This study demonstrates a reconfigurable wideband reflective polarizer from X to Ka-band applications. The design unitcell consists of a single PIN diode integrated metallic patch printed on a grounded dielectric substrate. When the PIN diode is reversely biased, the designed polarizer effectively converts a linearly polarized incident wave into a circular one with an effective 3 dB Axial Ratio (AR) from 8.88-9.82 GHz, 12.61-20.17 GHz and 23.67-25.08 GHz. In addition, it also performs linear-cross conversion with a minimum 90% Polarization Conversion Ratio (PCR) from 10.43-11.68 GHz and 21.27-22.78 GHz. While in the forward bias, this polarizer behaves as a perfect reflector in the lower frequency region, linear-cross conversion (21.90-23.38 GHz) and linear-circular from 19.85-21.08 GHz and 24.44-26.77 GHz. No performance degradation for oblique incidences is observed in the elevation plane up to 45°. The dual functionality is due to several surface plasmonic resonances supported by the patterns seen in the local electric field. The polarizer/reflector unitcell is very compacted (0.053λL×0.077 λL) and has a low-profile thickness of 0.047λL. Dual operation is of paramount importance in real-time applications and angular stable linear-cross, linear-circular polarizers and perfect reflectors at distinct frequency bands in a single design would be ideal in these cases. © 2023 IEEE.