Gain statistics for mobile phone antenna tuners

An adaptive tuning module is presented that allows the mismatch between the antenna and PA to be minimized. The tuner can operate in open and closed-loop modes. In both the open and closed-loop modes, static (time invariant) mismatch can be addressed, allowing the frequency dependence of the antenna and the RF front-end to be effectively compensated. Additionally, the closed-loop mode is capable of compensating the dynamic (time variant) mismatch that occurs due to user interaction (commonly also referred to as “the hand effect”). It is found that static and dynamic impedance variations are of the same order. However, the head and hand phantoms used in certification procedures do not represent the antenna impedance variations found in practice with real users. Because of this, the handset performance without a tuner is overestimated, whereas, the performance gains with an adaptive (closed-loop) tuner are underestimated. A new simple hand phantom has been developed to alleviate this problem. Since cellular networks are planned based on a certain confidence that a particular service level will be achieved, it is useful to look at the power delivered to the antenna in the same way. CDF´s of delivered power are presented without a tuner and with openand closed-loop variants of the same tuner hardware. It is shown that significant performance gains are possible (though this varies from band to band) and that closedloop tuners outperform open-loop tuners (the extent of which is determined by the severity of the dynamic impedance variation).