3-D Printed Inhomogeneous Substrate and Superstrate for Application in Dual-Band and Dual-CP Stacked Patch Antenna

This paper presents the extensive study on the effects of inhomogeneous substrate and superstrate for the exploration of dual-band and dual-circularly polarized patch antenna. As well known to all, the technology for circularly polarized (CP) patch antenna has been often restrictedly achieved by altering the shape of patch conductor surface by a few standard manufacturing processes. Benefited from the 3-D printing technology, it is demonstrated here that CP waves can be alternatively generated via an intact metal patch mounted on low-profile inhomogeneous substrate. As for the inhomogeneous superstrate, low profile is insufficient to make it become a polarizer. As such, a dual-band and dual-CP stacked patch antenna is proposed, where the lower patch and its superstrate exactly serve as the ground and substrate of the upper one. Different impacts of low-profile inhomogeneous substrate and superstrate on polarization are utilized to ensure the isolation of left- and right-hand circular polarizations. Besides, due to the usage of intact patches, two operating bands are independently formed and can be easily located in proximity to each other. A prototype operating at 2.75 and 3.2 GHz is then fabricated and measured. Measured results are found in reasonably a good agreement with the simulated ones.