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

ABSTRACT 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