Antenna design for a smartphone with a full metal casing and a narrow frame

A mobile‐phone antenna with a wideband feed structure (WBFS) and an auxiliary structure for a full metal casing and a very narrow frame are proposed. The most highlight of this proposed antenna is that it provides a method to overcome the difficulties of designing a high‐performance antenna in a full metal casing with a very narrow frame. The WBFS is designed to have a broadband performance. The total size of the antenna is 6 × 48 mm 2 , and a 6 mm long ground clearance is set on the bottom edge of the system circuit board. The experimental results reveal that a good impendence matching is obtained across the frequency bands of 824–960 and 1710–2690 MHz, and the total efficiency is more than 40%. The antenna maintains a good performance when user's hand(s) is (are) holding it; meanwhile, keeps the specific absorption rate (SAR) under the IEEE Std. C95.1 compliant SAR. In addition, the performance of the proposed antenna in a multi‐antenna system is examined. The result shows that the proposed antenna is a good candidate for a multiple‐input–multiple‐output system.