GPS/WLAN open-slot antenna with a sticker-like feed substrate for the metal-casing smartphone

ABSTRACT A multiband open‐slot antenna formed by placing a sticker‐like feed substrate (can also be a flexible printed‐circuit board) with the microstrip feedline and circuit elements disposed thereon onto a simple linear open slot embedded in the metal casing of the modern smartphone is presented. The proposed design provides a simple and convenient method in feeding an open‐slot antenna with multiband operation for the smartphone with a metal casing thereof having either a planar or smoothly curved surface. The linear slot has a short length of 23.5 mm and a narrow width of 1.5 mm and can be located 8 mm to the top or bottom edge of the metal casing. The linear slot is hence close to the short edge of the metal casing and will not be covered by the display panel therein. Such an open‐slot antenna is simple in structure and small in size, yet it can cover the GPS operation at 1.575 GHz and the 2.4/5.2/5.8‐GHz WLAN operation. The microstrip feedline printed on the feed substrate excites the open slot embedded in the metal casing, and the multiband (1.575/2.4/5.2/5.8 GHz) operation is obtained by the circuit elements disposed on the feed substrate. The circuit elements include a shunt capacitor loaded across the open slot and a parallel capacitor added to the microstrip feedline. Working principle of the applied circuit elements in obtaining the multiband operation is addressed. The antenna is also fabricated, and the experimental results are presented and discussed. © 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 58:1226–1232, 2016