Design of frequency tunable antennas for mobile devices

In mobile communications, frequency tunable antennas for handsets have become commonplace as it is increasingly difficult to cover all the necessary frequency bands required for mobile operation. This paper reviews the tuning technologies and components used in frequency tuning. Then the optimization criteria for tunable antennas are described. Typically, the minimum efficiency over the desired operation bands in maximized, but also conditions for the acceptable input matching level can be incorporated in the optimization. The optimization takes into account mismatch loss, component losses, radiation efficiency, losses in the tuning components and coupling to the other ports in multiantenna systems. Multiple impedance and efficiency data sets can be taken into account to make the matching circuits more robust to changes in the user environments.