Design of combined PIFAs with high port-to-port isolation for GSM/DCS and WLAN mobile phones

A novel design of combined PIFAs with high port-to-port isolation for GSM/DCS and WLAN mobile phones is presented. The antenna consists mainly of two planar inverted-F antennas (PIFAs), which are displaced closely with parts of the radiators reused. One of the PIFAs works at GSM900/DCS1800 bands (GSM-PIFA) and the other one works at WLAN/2.4 GHz band (WLAN-PIFA). To enhance the port-to-port isolation of the two PIFAs two techniques are used: first, the feeding coaxial-cable shield of the WLAN-PIFA is reused as the shorting strip of the GDPIFA; secondly, a rectangle slot is notched on the GSM-PIFA for further improving the isolation. A prototype has been implemented and tested, which shows that more than 20 dB isolation is obtained from 0.8 to 2.6 GHz.