Ground plane boosters to provide multi-band operation in wireless handheld devices

Recent demand for multifunctional wireless devices has increased the challenge for the antenna designers, who has to address it by providing small antennas able to operate in multiple communication standards. This paper proposes a new generation of radiating systems capable of providing multi-band operation without the need of including a dedicated antenna. The solution is based on the excitation of a structure already existing in any wireless handheld device, the ground plane. Said excitation is carried out through a pair of boosters with dimensions 5 mm × 5 mm × 5 mm, especially designed to transfer the maximum power to the efficient ground plane radiation mode. In addition, a radiofrequency system is combined with the booster-based radiating structure in order to provide penta-band operation. The feasibility of the proposal has been tested by electromagnetic simulations as well as by experimental measurements. Furthermore the human head interaction concerning Specific Absorption Rate (SAR) has been analyzed and a proposal for its reduction is presented. As a result a promising standard solution for a radiating system capable to operate in the main communication standards GSM850, GSM900, DCS, PCS and UMTS is provided with a volume reduction factor around 20 compared with current technologies.