A novel dual-band polarization-independent transmitarray is introduced in this paper for communication systems in Ka-band. Thanks to its unit-cell topology, the transmitarray antenna demonstrates almost complete independent performance at two design frequency bands of 20 GHz and 30 GHz. As a proof-of-concept, a transmitarray antenna prototype having a plate size of 80 x 80 mm(2) has been fabricated using printed board technology. A dual-band circularly polarized ridged cavity antenna feeds this planar structure and the relative translational displacement between the feed and transmitarray allows beam steering. The antenna performance has been validated via experimental results, which demonstrate good agreement with the theoretical and simulation predictions carried out with commercial software packages.