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

Abstract

Recent demand for multifunctional wireless devices has increased the challenge for the antenna designe rs, who has to address it by providing small antennas able to oper ate in multiple communication standards. This paper propos es a new generation of radiating systems capable of providin g 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 booster s with dimensions 5 mm x 5 mm x 5 mm, especially designed to transfer the maximum power to the efficient ground plane rad iation mode. In addition, a radiofrequency system is combi ned with the booster-based radiating structure in order to provi de penta-band operation. The feasibility of the proposal has been tested by electromagnetic simulations as well as by experimen tal measurements. Furthermore the human head interactio n 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 te chnologies