Penta-band one-eighth wavelength PIFA for internal mobile phone antenna

A planar lambda/8-PIFA with a coupling feed for achieving GSM850/900/1800/ 1900/UMTS operation in the mobile phone has been proposed and studied. With penta-band operation obtained for WWAN communication, the proposed lambda/8-PIFA occupies a small area of 7 times 40 mm² on an inexpensive 1.6-mm thick FR4 substrate. The compact size of the proposed PIFA also makes it promising to be embedded inside the casing of the mobile phone to operate as an internal antenna. In addition, two lambda/8 modes are excited at close frequencies around 900 MHz to form a wide operating band for the antenna´s lower band by using a common coupling feed. Further, two higher-order modes (lambda/4 modes) are also successfully excited at close frequencies around 1900 MHz to provide a wide operating band for the antenna´s upper band. The obtained wide lower and upper bands allow the proposed PIFA to cover GSM850/900/1800/1900/UMTS penta-band operation for WWAN communication. The proposed planar lambda/8-PIFA is promising for practical application in the mobile phone for WWAN communication.