Low-Profile Dual-Band Circularly Polarized Antenna Combining Transmitarray and Reflectarray for Satellite Communications

This communication proposes a low-profile dual-band circularly polarized (CP) antenna for satellite communication at K- and Ka-bands. The antenna consists of a folded transmitarray (TA) operating at 20 GHz and a multi-feed reflectarray (RA) operating at 30 GHz. The dual split rings are used as the TA and RA elements. The TA is placed above the RA. The TA acts as the phase-controlling surface at 20 GHz and does not affect the transmission of plane waves at 30 GHz generated by the RA. The RA simultaneously serves as the phase-controlling surface at 30 GHz and as the ground for the folded TA at 20 GHz. Owing to the combination of the folded TA and multi-feed RA with a small focal length-to-diameter ratio, the antenna profile is reduced, and the height-to-diameter ratio is only 0.4. Compared with the traditional horn feed system, the CP patch arrays integrated on the TA surface are used as the feeds in this design. The orthomode transducer (OMT) and circular polarizer are not needed, which significantly saves space and cost. The antenna was manufactured and measured to verify its performance. The measured results keep good consistent with the simulated results.