Ultra-low-profile Broadband Circularly Polarized Folded Transmitarray Antenna Based on Double Phase-compensation

A broadband circularly polarized folded transmitarray antenna (FTA) with ultra-low profile is designed in this paper. By using double phase compensation with the reflective- and the transmission array, the ratio of antenna height to aperture diameter ($\mathrm{H} / \mathrm{D}$) is successfully reduced to 0.15. The transmitarray selectively transmits x-polarized wave and radiates the right-handed circularly polarized one. With the miniaturized multi-resonant transmitting units, stable transmission amplitude and phase compensation can be realized within a wide incidentangle volume and a broad bandwidth. Therefore, The broadband radiation performance is ensured under the ultra-low profile. Simulation results indicate that a gain of 26.5 dBi at 9.7 GHz, a 3 dB gain bandwidth of $\mathbf{2 5. 4 \%}$, and a 3 dB axial ratio bandwidth of $28 \%$ have been achieved.