This work proposes a novel wideband reconfigurable via-less Frequency Selective Surface (FSS) based linear-circular, linear-cross polarizer in both reflection and transmission modes. The design consists of top and bottom FSSs on either side of the Taconic TLY-5 substrate. PIN diodes mounted on the back FSS turn the polarizer transmissive and reflective in different states. For a linearly polarized wave incidence, the transmitted wave would be circularly polarized with a 3 dB Axial Ratio (AR) from 8.03-16.30 GHz (67.98%) and 30.05-31.70 GHz (5.54%). In reflection mode, this design performs linear-circular conversion in 9.38-10.49 GHz (11.17%) and 15.14-30.27 GHz (66.64%). On the other hand, the unitcell behaves as a reflective linear-cross converter with a minimum 90% Polarization Conversion Ratio over 11.43-13.43 GHz (16.09%) and 31.67-34 GHz (7.10%). Multiple surface plasmonic resonances are the reason behind the different conversions. The unitcell periodicity (0.150λL× 0.123λL) is the compact and low-profile thickness of 0.043λL. The proposed work's novelty lies in the miniaturized architecture of the linear-circular polarization converter, covering the lower frequency (X/Ku) in transmission mode and higher frequency (Ku/K) in the reflection mode, which made this polarizer a suitable candidate for vehicular satellite communication applications. IEEE