Heterogeneous Metasurface Empowering Proximate High-Permittivity Ceramic Cover for a 5G Dual-Band Millimeter-Wave Smartphone

This study presents a heterogeneous metasurface that facilitates the close integration of a high-permittivity ceramic back cover into a 5G dual-band millimeter-wave (mmWave) smartphone. The metasurface can be applied to various types of target antennas without additional modification to the antenna design. Furthermore, the proposed metasurface technology is significant because it enables the active use of ceramic covers in 5G mmWave smartphones. Despite its many design and practical advantages, the ceramic cover could not be applied in 5G mmWave smartphones, because of its high reflection loss in the FR2 bands. A transmissive metasurface that eliminates this high reflection loss and further improves the antenna performance is designed at an extremely close distance to the antenna-in-package (AiP). A heterogeneous unit cell grouping topology is proposed to achieve dual-bandwidth control and wide bandwidth. The influence of the distance between the metasurface and AiP is investigated to determine near-field compatibility and design compactness. Five distinct antenna arrays, including a commercial AiP embedded in a 5G smartphone, are simulated with and without metasurfaces, and an effective isotropically radiated power (EIRP) and cumulative distribution function (CDF) is measured using the mobile call test, including the AiP and metasurface-attached ceramic cover, to verify gain, and beam coverage enhancement.