Low-Profile Circularly Polarized Double-Folded Transmitarray Antenna

A low-profile circularly polarized (CP) double-folded transmitarray antenna (DFTA) is proposed. The DFTA consists of a receiver-transmitter transmitarray surface (TS), a polarization rotating surface (PRS) and a patch antenna. The linearly polarized (LP) wave radiated by the patch antenna is rotated twice, then received and converted into CP wave by the TS, and finally radiated into free space with transmission phase manipulation. Therefore, the LP spherical wave from the patch antenna can be transduced into the high-gain CP plane wave. This design greatly decreases the profile of TA to about a quarter of the focal length. The simulated results show that the proposed antenna has a gain of 20.6dBic with an aperture efficiency of 21.4% at 13GHz, and a -3dB gain bandwidth of 10.8%, in which the axial ratio is less than 3dB.