AbstractThis paper describes a metamaterial‐based miniaturized circularly polarized (CP) antenna with high radiation efficiency and wide beam‐width or coverage for 5G indoor application. A novel meta‐resonator is first proposed, which is investigated by transmission line and equivalent circuit models. By exploring a split‐ring resonator‐like meta‐resonator structure, a high‐Q LC resonator tank is formed. Substantial size reduction and a wide beam‐width are achieved. Owing to a uniform field on these multiple capacitive gaps incorporated on this meta‐resonator surface, enhanced aperture efficiency and gain are obtained. It is partly inspired by the classical metasurface‐based antenna. For validation, a miniaturized CP antenna with a size of 0.29 λ0 × 0.29 λ0 × 0.04 λ0 (where, λ0 is the free‐space wavelength at 3.55 GHz) is fabricated and measured. The fabricated antenna achieves a good bandwidth of 3.30–3.80 GHz that well covers 5G‐N78 band, a peak radiation gain of 5.4 dBic, a high radiation efficiency of 90% and a wide half‐power beam‐width of 91°. It exhibits the merits of compact size, good bandwidth and beam‐width, high efficiency, and low‐cost, demonstrating good potential in miniaturized 5G indoor systems demanding wide‐beam coverage.