A Wideband Circularly Polarized Folded Reflectarray Antenna With Linearly Polarized Feed

The design and implementation of a wideband circularly polarized folded reflectarray antenna (CPFRA) with a linearly polarized (LP) feed antenna is presented in this letter. The subreflector of the proposed CPFRA is in the form of a polarization-sensitive frequency selective surface (FSS) based on the antenna-filter-antenna (AFA) technology other than the traditional polarizing grid. The AFA FSS is designed to convert the LP incident wave into circularly polarized (CP) wave within its passband and reflect the orthogonal LP incident wave over a wide frequency band. Futhermore, the sequential rotation technique is applied in the design of main reflectarray and subreflector to greatly enhance the axial ratio (AR) bandwidth of the CPFRA. An antenna prototype has been fabricated and measured at
X
-band. Good agreement between the measured and simulated results has been achieved by the wideband CPFRA. The measured results show that the maximum antenna gain reaches up to 28.2 dBic at 10.2 GHz with its aperture efficiency of 43.3%. The 3 dB gain frequency band is from 9.1 to 10.6 GHz and the 3 dB AR frequency band from 8.7 to 11.2 GHz, respectively.