A Novel Dual-Band Shared-Aperture Antenna Based on Folded Reflectarray and Fabry–Perot Cavity

This communication proposes a novel dual-band shared-aperture antenna hybridizing Fabry–Perot cavity antenna (FPCA) and folded reflectarray (FRA), which operates at both sub-6 GHz and millimeter-wave bands with a large frequency ratio of 1:4.6. This antenna is composed of two substrates, with metasurface printed on the upper substrate and reflector layer printed on the lower one. The metasurface works as partially reflective surface (PRS) of FPCA at the sub-6 GHz band while acts as polarization grid of FRA at the millimeter-waveband. Thus, the FPCA and the FRA are able to share the same aperture with high aperture reuse efficiency. A composite feed structure combining waveguide with microstrip patch antenna is used to feed at two bands, implementing shared-aperture feed. This antenna achieves high gains at two bands without complicated feeding networks. A prototype operating at 5.4 and 25 GHz bands is designed, fabricated, and measured to verify the idea.