Miniature and Higher-order Mode Ferrite Mimo Ring Patch Antenna for Mobile Commu- Nication System

Abstract—Miniaturized ferrite ring patch antennas (RPAs) were designed and fabricated for multiple-input multiple-out (MIMO) applications. Design parameters of higher-order mode ferrite RPAs, 1-RPA and 2-RPA, were optimized, and antenna performance of the ferrite 1-RPA was evaluated. The Z-type hexaferrite and 2%-weight borosilicate glass composite was used for the ferrite antenna disk. The measured permeability (μr) and permittivity (εr) of the hexaferrite were 2.59 and 5.7, respectively, at 2.5 GHz. Three-mode orthogonal radiation of the ferrite 1-RPA was experimentally confirmed. With regard to the ferrite 2-RPA, excellent isolation (−40 dB) between ports 1 and 2 was achieved at 2.5 GHz. This excellent isolation property is attributed to both mode 3 orthogonal radiations of the bottom and top RPAs. The volumes of the 1and 2-RPA were reduced to 14.5% and 34.5%, respectively, from 95 cm3 of a dielectric 2-circular patch antenna (2-CPA) volume.