Multiband and small coplanar antenna system for wireless handheld devices

Multiband and small antennas are strongly demanded in current wireless handheld or portable devices that require multiband operation. Nowadays, trends are focused on exciting ground plane radiation modes in order to reduce as much as possible the volume devoted to the antenna element. This paper studies different geometries for determining which one better excites a ground plane radiation mode at different frequency regions. The results demonstrate that a non-resonant pad element attains the best tradeoff between performance and geometry complexity. A multiband antenna system featuring small coplanar pad elements is proposed for providing operation at the communication standards LTE700 (698-787 MHz), GSM850 (824-894 MHz), GSM900 (880-960 MHz), GSM1800 (1710-1880 MHz), GSM1900 (1850-1990 MHz), UMTS (1920-2170 MHz), LTE2100 (1920-2170 MHz), LTE2300 (2300-2400 MHz), LTE2500 (2500-2690 MHz) as well as at the satellite positioning systems GPS (1575 MHz), Galileo L1 (1559-1591 MHz), Glonass (1592-1609 MHz). A radiofrequency system comprising broadband matching networks is included to provide the required impedance bandwidth. Numerical results give physical insight into the behavior of the proposed planar element. A prototype is built to demonstrate the feasibility of the proposal. The proposed radiating system is appealing for the new wireless handheld devices due to its small size (153 mm²), planar profile, and multiband performance.