Frequency-Tunable Planar Monopole Antenna for Mobile Terminals

A frequency tunable planar monopole antenna for mobile terminal applications is presented. The operating frequency of the antenna is electrically switched from the DCS (1710-1880 MHz) to the WLAN (2400-2484 MHz) bands. This is done by using a RF pin diode switch situated in the middle of the antenna. The size of the antenna is 14 x 15 mm², and it covers both bands with over 60 % total antenna efficiency margin. The impact of tuning on the resonant frequency of the antennas, total antenna efficiency and radiation pattern are experimentally studied and compared with reference antennas that have no tuning circuit.