Coupled-fed small-size PIFA for penta-band folder-type mobile phone application

A small-size planar inverted-F antennas (PIFA) for penta-band operation in the folder-type mobile phone is presented. The PIFA occupies a small volume of 2.1 cm³ only. Instead of using the conventional direct contact feed, the proposed PIFA uses a coupling feed, which allows the antenna in its open state or talk condition to generate a dual-resonance lower band of bandwidth 300 MHz (780-1080 MHz, 3:1 VSWR or 6-dB return loss) to cover GSM850/900 operation. In addition, the PIFA can also generate a very wide upper band of band-width 925 MHz (1368-2293 MHz) to cover GSM1800/1900/UMTS operation. When the mobile phone is in its close state or standby condition, the obtained lower and upper bands can still cover GSM850/900/1800/ 1900/UMTS penta-band operation with impedance matching better than 6:1 VSWR or 3-dB return loss, which is acceptable for the mobile phone in standby condition for practical applications. Details of the proposed PIFA and the obtained results are presented.