Small‐size narrow open‐slot antenna for the 2.4/5.2/5.8‐GHz WLAN operation along the side edge of the metal‐framed smartphone

A small-size narrow open-slot antenna with 1-mm slot width and 12.7-mm slot length promising to be disposed in the narrow region along the side edge of the metal-framed smartphone for the 2.4/5.2/5.8-GHz WLAN operation is presented. This study exploits the narrow region between the display panel and the casing of the metal-framed smartphone to dispose the internal antenna therein. The proposed antenna is fed using a microstrip feedline with its tuning stub disposed within the slot, thereby keeping narrow width of the antenna. The open slot (denoted as a first slot) has a 1-mm opening disposed at the metal frame, and its length corresponds to only about 0.1 wavelength at 2450 MHz, which supports a fundamental open-slot mode to cover the 2.4 GHz band. In addition, with a chip capacitor (1.1 pF) loaded at a proper position across the first slot, the antenna can be reconfigured at about 5.2 GHz to create a new resonant open slot (second slot) from the capacitor to the slot opening. This second slot contributes to a new resonant mode for the antenna to cover the 5.2 GHz band. By embedding a series chip inductor (1.5 nH) in the microstrip feedline, a higher-order slot mode supported by the first slot can be shifted to cover the 5.8 GHz band. The antenna can hence cover the 2.4/5.2/5.8-GHz WLAN operation with a compact and narrow slot structure. Details of the proposed antenna are described. © 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 58:886–892, 2016