Tunable PIFA slot antenna for mobile handset and WLAN applications

A frequency tunable antenna for covering the digital cellular system (DCS; 1710-1880 MHz), personal communication service (PCS; 1850-1990 MHz), universal mobile telecommunications system (UMTS; 1900-2200 MHz), wireless LAN (WLAN; 2400 MHz) bands is presented. The proposed antenna consists of a main patch and a planar inverted-F-with L slit. The antenna is fed and shorted using a simple feed lines having broadband characteristic through the handset that represents the equivalent finite ground plane. A varactor diode is mounted across the middle of the slot for tuning purposes. Tunability has been accomplished first by placing lumped capacitors instead of a varactor diode range of 0.5-3.3 pF on the antenna radiator element for frequency shift. Good agreement is obtained between computed and measured of the most of antenna performances.