An embedded tri-band planar inverted-F antenna with a branch-line shorting strip

By using a branch-line shorting strip, a novel planar inverted-F antenna (PIFA) suitable for the application as a GSM/DCS/PCS tri-band mobile phone internal antenna has been obtained. The proposed antenna has three resonant elements, two shorter radiating strips of slightly different lengths and one longer radiating strip, which are fabricated via stamping process and supported by a plastic holder. These three resonant elements share the branch-line shorting strip and generate three resonant modes, one on lower band from the first-order mode of the longer radiating strip for the EGSM (880-960 MHz) operation and two on upper band which is generated by the two shorter radiation strips, leading to a wide bandwidth covering the DCS (1710-1880 MHz) and PCS (1850-1990 MHz) bands. The proposed antenna has also a good radiation performance as the radiation efficiency more than 50%. Details of the antenna design and experimental results are presented and discussed