This paper presents a double layer double ring unit cell for circular polarization transmitarrays. The proposed unit cell is evaluated with Rogers 4003 and FR4 substrates. Both models are applied to the design of a 13 x 13 elements transmitarray with a log spiral feeder at 10 GHz. Results show that the transmitarray achieves a directivity of 20.7 dBi and 20.0 dBi at the boresight, with Rogers 4003 and FR4 substrates, respectively, which is nearly 12 dB above the log spiral gain. The results of the proposed transmitarray are compared with a horn antenna and a toroidal plasma lens. When compared with solutions that present equivalent boresight directivity, the proposed transmitarray achieves significantly reduced profile, showing to be a high gain low cost, low profile and easy to prototype solution.