The interaction between a mobile phone antenna and its environment (for example the user hand and head) modifies the radiating elements impedance. The antenna then presents an impedance which is different from the power amplifier one. Besides, the 4G context introduces new constraints on the antenna to guarantee higher data rates on more frequency bands. In order to decrease the user interaction, while considering the 4G challenges, two area of research have been studied in this work. The first solution that we have evaluated consists in inserting a tuner between the radiating element and the front end module, in order to counteract the antenna mismatch and to present an impedance close to 50 Ohms to the power amplifier. Prototypes have been realized using CMOS SOI 130 nm technology from STMicroelectronics. Obtained performances are at the state of the art, but the behavior of the tuner which is narrowband in phase showed that the co-design with the antenna is mandatory in order to demonstrate the tuner interest. The second developed line of research consists in realizing a wideband antenna, combining antenna and circuit design techniques. Demonstrators have been manufactured using the LDS-LPKF process. Smartphones prototypes have been proposed to implement the antenna in a realistic way to characterize their impedance and radiating behavior. Measurement shows a good robustness to the user interaction (in terms of matching) and efficiencies with similar values to commercial phones ones, while guaranteeing an operation in 4G bands and enabling carrier aggregation. As this method is scalable and compatible with the plastronics integration (components are integrated on the plastic), these prototypes paves the way for numerous perspectives, to cover different applications in the medical, wireless sensors network or the automotive areas.
