Miniature Millimeter-Wave 5G Antenna Fabricated Using Anodized Aluminum Oxide for Mobile Devices

A miniature millimeter-wave 5G antenna fabricated using anodized aluminum oxide (AAO) is devised and demonstrated for mobile devices. The proposed structure creates a dielectric layer on an aluminum plate using AAO topology and allows the antenna pattern to be placed on the dielectric layer. The proposed AAO-based antenna reduces the size (1.87 (0.18λ₀) mm × 2.34 (0.22λ₀) mm) of the antenna in proportion to the dielectric constant (ε_r = 6.7), which is higher than those of the conventional materials such as polycarbonates (PC) or a flame retardant (FR4). In addition, it is possible to precisely control the dielectric layer dimensions and generate a dielectric layer on the metal substrate itself, which greatly increases the design freedom. As a result, the devised antenna resonates at 29 GHz, and the measured gain is 5.02 dBi.