In this article, an ultrathin (λ0/14.9), single layer, reflective type polarization converter for either linear-to-circular (LP-to-CP) or linear-to-linear (LP-to-LP) polarization conversion is reported. It has been demonstrated to achieve the LP-to-CP conversion at two separate frequency bands, including 11.52-11.84GHz and 19.83-20.01GHz. The circular polarization type is specified as a right-hand circular polarization (RHCP) for the first band and a left-hand circular polarization (LHCP) for the second band. In both of frequency bands, the metasurface structure reveals highly efficient features. Besides that, the metasurface structure exhibits highly efficient features within 3-dB bandwidths of 10.29-12.58GHz and 19.32-20.50GHz. Crucial parameters of polarization conversion such as ellipticity, axial ratio, and |Eco|/|Ecross| are confirmed to be in good agreement with another one. The metasurface structure's angular stability up to 200 oblique incidence angles makes it useful for beam scanning antennas. CST Microwave Studio program is utilized to carry out extensive simulations. This presented study offers a low cost, relatively high-performance, ultrathin polarization converter capable of linear-to-linear and circular polarization conversion in the X-, Ku-, and K-bands.