A wideband built-in antenna with omni-directional radiation pattern using dual radiators for wireless terminals

A new built-in antenna is proposed with omni-directional radiation characteristics and wideband for wireless terminals. Bandwidth of built-in antenna is dependent on length and width of the chassis [Outi Kivekas (2003)]. Radiation characteristics of built-in antenna are also very sensitive to chassis size and mounting position. When size of chassis is increased, radiation pattern characteristics of built-in antenna are more degenerative in the high frequencies (1800MHz∼2200MHz) than those of antenna in the low frequency (900MHz) among current cellular services. This paper proposes a balanced dual radiators built-in antenna with special impedance matching branch for bar-type handsets (45mm × 100mm), which built-in antenna is operating at PCS and IMT-2000 band. Using suggested technique, we improved -6dB impedance bandwidth by about 75% and also obtain the omni-directional radiation pattern even though which is mounted on relatively large chassis.