Dual-Band Circularly Polarized Antenna Design using PIDFS

Based on the design concept described in Section II, a prototype of the proposed dual-band circularly polarized antenna is designed using the PIDFS, which is constructed by the proposed UC shown in Fig. 7(a). The PIDFS consists of a dual-function metasurface and two polarizers. For demonstration purposes, the dual-functional metasurface is composed of 196 UCs (14 ￗ 14 UCs) to balance realized gains and efficiency.

The total antenna structure integrates a RA and an FPC. The RA consists of the PIDFS and a horn antenna operating at a higher frequency band. The horn antenna emits electromagnetic waves, which are focused and reflected back in the z-axis direction by the PIDFS, resulting in a circularly polarized wave. The FPC antenna includes the PIDFS, a magneto-electric (ME) dipole operating at a lower frequency band as a feed, and a bottom ground. The ground of the magneto-electric dipole feed is enlarged to enhance energy reflection. Using the magneto-electric dipole as the feed for the lower frequency band ensures a consistent beamwidth for both the E-plane and H-plane, ensuring more uniform electromagnetic energy reception across the entire PIDFS. The detailed configurations and dimensions of the proposed metallic ME dipole are illustrated in Fig. 9. The magneto-electric dipole radiates a wave with an electric field aligned along the y-axis, which converges into a circularly polarized beam after transmitting through the PIDFS.