A Triple-Band Cavity-Shared Fabry–Perot Cavity Antenna With High Aperture Efficiency for Vehicular Communications and Sensing

A novel cavity-shared triple-band high-gain antenna hybridizing a 5G-A band Fabry-Perot cavity antenna (FPCA) and a K/Ka-band reflectarray (RA) is proposed. The reported FPCA−RA configuration typically adopts the aperture-shared methodology to realize multi-frequency hybridization which integrates the RA in the partially reflective surface (PRS) or ground plane of the FPCA. Differences in working bands and aperture occupation by the low band feed make it difficult to have proper unit period and complete phase distribution simultaneously for the high-band RA. Therefore, the aperture efficiency of the RA in this configuration is low which can hardly exceed 30%. Distinct from the reported aperture-shared architecture, the FP-cavity itself is excavated as a new platform to realize cavity-shared multi-frequency hybridization. The high-band RA is directly inserted inside the cavity without integration with the low-band PRS or ground, it hence obtains a complete phase profile and suitable unit periodicity simultaneously which endows the RA with higher aperture efficiency. Further, the cavity-shared antenna architecture simplifies the multi-frequency hybridization. Both K- /Ka-band RAs are inserted inside the cavity. A triband frequency selective surface and a simple ground are used to construct the FPC. A higher than 50% aperture efficiency is obtained in all operating bands. The proposed triple-band antenna can be potentially applied in space-constrained vehicular communication and sensing systems.