A Dual-Band Dual-Circularly Polarized Folded Transmitarray Antenna With Compact Aperture

A dual-band dual-circular polarization (CP) folded transmitarray (FTA) antenna is presented, radiating left- and right-hand CP waves at 10.4 GHz and 13.4 GHz, respectively. This innovative FTA incorporates receiver-transmitter metasurface (RTMS), polarization rotating metasurface, and a dual-band linear polarization (LP) patch antenna. The RTMS effectively reflects and transmits distinct LP waves in two bands while providing phase compensation. A phase compensation method that considers the phase center of the feed is proposed, by which the axial ratio characteristic is enhanced. Measurement results demonstrate that the proposed FTA achieves high performance with the following characteristics: In the lower band, it achieves a 3 dB gain bandwidth (BW) of 10.2% (10.1-11.2 GHz) and a 3 dB axial ratio BW of 14.3% (10.2-11.7 GHz), with peak radiation efficiency reaching 23.5%. The higher band exhibits a 3 dB gain BW of 7.0% (12.9-13.9 GHz) and a 3 dB axial ratio BW of 11.9% (12.7-14.3 GHz), accompanied by a peak efficiency of 8.9%.