In this paper, we propose to study and validate a dual-band dual linearly-polarized transmitarray with 1-bit phase resolution based on the superposition technology. The objective is to compare the superposition approach with the interleaving approach to generate a dual-band operation, in term of beam-scanning performances. The two antennas operates in both downlink and uplink K/Ka-bands (17-21 GHz for the downlink, and 27-31 GHz for the uplink). The unit-cells includes four printed U-slotted patch and a connecting via; a 180° phase shift is obtained by rotating one of the patches around its corresponding via. A 40x40 transmitarray based on the proposed architectures have been studied numerically. The simulated results show that the transmitarray based on the superposition method achieves beam steering with the scan range of ± 70° at 29 GHz.