Balanced antennas for mobile handset applications. Simulation and Measurement of Balanced Antennas for Mobile Handsets, investigating Specific Absorption Rate when operated near the human body, and a Coplanar Waveguide alternative to the Balanced Feed.

摘要

The main objectives of this research are to investigate and design low profile antennasudfor mobile handsets applications using the balanced concept. These antennas areudconsidered to cover a wide range of wireless standards such as: DCS (1710¿1880 MHz),udPCS (1850¿1990 MHz), UMTS (1920¿2170 MHz), WLAN (2400¿2500 MHz and 5000ud¿ 5800 MHz) and UWB frequency bands. Various antennas are implemented based onudbuilt-in planar dipole with a folded arm structure.udThe performance of several designed antennas in terms of input return loss, radiationudpatterns, radiation efficiency and power gain are presented and several remarkableudresults are obtained. The measurements confirm the theoretical design concept and showudreasonable agreement with computations. The stability performance of the proposedudantenna is also evaluated by analysing the current distribution on the mobile phoneudground plane. The specific absorption rate (SAR) performance of the antenna is alsoudstudied experimentally by measuring antenna near field exposure. The measurementudresults are correlated with the calculated ones.udA new dual-band balanced antenna using coplanar waveguide structure is also proposed,uddiscussed and tested; this is intended to eliminate the balanced feed network. Theudpredicted and measured results show good agreement, confirming good impedanceudbandwidth characteristics and excellent dual-band performance.udIn addition, a hybrid method to model the human body interaction with a dual bandudbalanced antenna structure covering the 2.4 GHz and 5.2 GHz bands is presented.udResults for several test cases of antenna locations on the body are presented anduddiscussed. The near and far fields were incorporated to provide a full understanding ofudthe impact on human tissue. The cumulative distribution function of the radiationudefficiency and absorbed power are also evaluated.